EA045179B1 - METHODS FOR OBTAINING A PRODUCT IN THE FORM OF TITANIUM ALLOY - Google Patents

Description

Government funding

The present invention was made with government support under Grant No. DE-AR0000420 issued by the Department of Energy. The government has certain rights to an invention.

State of the art

Titanium is strong, lightweight, corrosion resistant and biocompatible. This unique combination of properties makes it a valuable natural resource highly suitable for a variety of potential industrial applications. Titanium has been produced on an industrial scale since at least 1948, and is widely used in the aerospace, medical and defense industries. For example, the USGS Mining Industry Survey of Titanium reports that approximately 67% of rolled and cast products during 2011 were used for industrial and military aerospace applications. For now, other industries that would benefit from titanium still rely heavily on steel as a versatile material. The high dependence on steel is not unexpected, since producing titanium using standard methods can be twenty times more expensive than producing steel. Much of this high cost is due to the indirect nature of known processes that are time consuming and energy intensive, such as the carbothermic reduction and metallothermic reduction of titanium chloride processes known as the Kroll and Hunter processes. More recently, attempts to identify more economical methods for producing titanium have included the Armstrong process, the FCC Cambridge electrolysis process, and the like.

In addition to these problems, the formation of titanium alloys poses unique challenges. For example, it is very difficult to obtain materials from alloys with high homogeneity in large quantities. A typical production of a titanium alloy begins by subjecting titanium sponge, which is often commercially pure titanium (CP-Ti), and an alloy (eg, AIV) to a vacuum arc remelting (VAR) process. This method involves melting an electrode in a copper crucible to produce a homogeneous mixture of titanium sponge and master alloy. Industrial scale VAR processes also use 1 to 10 tons of ingots in furnaces that are ten to twenty feet high. To obtain high-purity titanium alloys, the VAR process must be carried out repeatedly (for example, 2-3 times), which involves cyclic unloading and supplying a large amount of energy. Thus, there remains a need for a simplified and less expensive method for producing titanium metal and, in particular, titanium alloys. The essence of the invention

To form powdered titanium alloys, a solid state alloying method can be used, alloyed with one or many elements such as Al, Mo, V, Nb, Ta, Fe, Cr, Mn, Co, Cu, W, Al, Zr, Sn, Ni, Si, and other elements. Typically, a method for producing a dispersed product in the form of a titanium alloy may include producing a mixture of composite dispersed oxides from TiO ₂ powder and powder of at least one alloying element. The mixture of composite dispersed oxides can be co-reduced using a metal reducing agent, preferably in an at least partially hydrogen-containing atmosphere, at a reduction temperature for a reduction time sufficient to form a hydrogenated titanium alloy product. The hydrogenated titanium alloy product may then be heat treated under a hydrogen atmosphere and heat treatment temperature to reduce pore size and specific surface area to form a heat treated hydrogenated titanium product. The heat-treated hydrogenated titanium product can be deoxygenated to reduce the residual oxygen content to less than 0.3 wt.% (or often <0.15%) to form the deoxygenated hydrogenated titanium product. The deoxygenated hydrogenated titanium product may optionally be dehydrogenated to form a titanium alloy product. It should be noted that the deoxygenated hydrogenated titanium product and the titanium alloy product as a product are dispersed powders.

The most important features of the invention have thereby been outlined, in a fairly broad sense, so that the detailed description of it that follows may be better understood, and so that the real contribution to technology can be better appreciated. Other features of the present invention will become more apparent from the following detailed description of the invention given in conjunction with the accompanying drawings and claims, or may be learned by practice of the invention.

Brief description of drawings

Fig. 1 is a process flow diagram illustrating a process for producing a particulate titanium alloy product.

Fig. 2A is a plot of theoretical calculations showing the relative co-reduction of certain oxides by stoichiometric amounts of Mg in hydrogen.

Fig. 2B is a reproduction of FIG. 2A with the y-axis enlarged to show the ratios of hydrides and oxides in more detail.

Fig. 2C illustrates the relative co-reduction in hydrogen of certain oxides with 1.2 times the stoichiometric ratio of Mg.

Fig. 2D illustrates the relative co-reduction in hydrogen of certain oxides with 1.5 times the stoichiometric amounts of Mg.

Fig. 2E illustrates the relative co-reduction of these oxides in argon at 1.2 times the stoichiometric ratio.

Fig. 2F illustrates the relative co-reduction of these oxides in argon at 1.5 times the stoichiometric ratio.

Fig. 3A is a scanning electron microscope (SEM) micrograph of partially sintered metal oxide composite alloy particles in accordance with Example 1.

Fig. 3B is an enlarged SEM micrograph of a portion of FIG. 3A.

Fig. 3C is an SEM micrograph of the hydrogenated and reduced alloy powder prepared in accordance with Example 1.

Fig. 3D is an enlarged SEM micrograph of a portion of FIG. 3C.

Fig. 3E is an SEM micrograph of a heat-treated alloy powder prepared in accordance with Example 1.

Fig. 3F is an enlarged SEM micrograph of a portion of FIG. 3E.

Fig. 3G is an SEM micrograph of deoxygenated alloy powder prepared in accordance with Example 1.

Fig. 3H is an enlarged SEM micrograph of a portion of FIG. 3G.

Fig. 4A is an SEM micrograph of partially sintered metal oxide alloy composite particles according to Example 2.

Fig. 4B is an enlarged SEM micrograph of a portion of FIG. 4A.

Fig. 4C is an SEM micrograph of the hydrogenated and reduced alloy powder prepared in accordance with Example 2.

Fig. 4D is an SEM micrograph of a heat-treated alloy powder prepared in accordance with Example 2.

Fig. 4E is an enlarged SEM micrograph of a portion of FIG. 4D.

Fig. 4F is an SEM micrograph of deoxygenated alloy powder prepared in accordance with Example 2.

Fig. 4G is an enlarged SEM micrograph of a portion of FIG. 4F.

Fig. 5A is an SEM micrograph of partially sintered metal oxide alloy composite particles according to Example 3.

Fig. 5B is an enlarged SEM micrograph of a portion of FIG. 5A.

Fig. 5C is an SEM micrograph of the hydrogenated and reduced alloy powder prepared in accordance with Example 3.

Fig. 5D is an enlarged SEM micrograph of a portion of FIG. 5C.

Fig. 5E is an SEM micrograph of a heat-treated alloy powder prepared in accordance with Example 3.

Fig. 5F is an enlarged SEM micrograph of a portion of FIG. 5E.

Fig. 5G is an SEM micrograph of deoxygenated alloy powder prepared in accordance with Example 3.

Fig. 5H is an enlarged SEM micrograph of a portion of FIG. 5G.

Fig. 6A is an SEM micrograph of partially sintered metal oxide alloy composite particles according to Example 4.

Fig. 6B is an enlarged SEM micrograph of a portion of FIG. 6A.

Fig. 6C is an SEM micrograph of the hydrogenated and reduced alloy powder prepared in accordance with Example 4.

Fig. 6D is an enlarged SEM micrograph of a portion of FIG. 6C.

Fig. 6E is an SEM micrograph of a heat-treated alloy powder prepared in accordance with Example 4.

Fig. 6F is an enlarged SEM micrograph of a portion of FIG. 6E.

Fig. 7A is an SEM micrograph of partially sintered metal oxide alloy composite particles according to Example 5 (A5).

Fig. 7B is an enlarged SEM micrograph of a portion of FIG. 7A.

Fig. 7C is an SEM micrograph of partially sintered metal oxide alloy composite particles prepared in accordance with Example 5 (A6).

Fig. 7D is an enlarged SEM micrograph of a portion of FIG. 7C.

Fig. 7E is an SEM micrograph of sample A5 after co-reduction according to Example 5.

Fig. 7F is an SEM micrograph of sample A6 after co-reduction according to Example 5.

Fig. 7G is an SEM micrograph of sample A5 after heat treatment in accordance with Example 5.

Fig. 7H represents an SEM micrograph of sample A6 after heat treatment in accordance with Example 5.

Fig. 7I is an SEM micrograph of sample A5 after deoxygenation according to Example 5.

Fig. 7J is an SEM micrograph of sample A6 after deoxygenation according to Example 5.

These drawings are provided to illustrate various aspects of the invention, and are not intended to limit the scope in terms of dimensions, materials, configurations, arrangements and proportions, unless otherwise limited by the claims.

Detailed Description of an Embodiment of the Invention

While exemplary embodiments have been described in sufficient detail to enable those skilled in the art to practice the invention, it should be understood that other embodiments may be implemented and that various modifications of the invention may be made without departing from the spirit and scope of the present inventions. Thus, the following more detailed description of embodiments of the present invention is not intended to limit the scope of the invention as claimed, but is presented for purposes of illustration only, and not to limit the description of the features and characteristics of the present invention, to set forth the best embodiment of the invention, and to sufficiently enable a qualified specialist in this field of technology to put the invention into practice. Accordingly, the scope of the present invention is to be defined only by the claims contained in the appended claims.

Definitions

As the present invention is described and claimed, the following terminology will be used.

Singular forms include plural entities unless the context clearly requires otherwise. Thus, for example, reference to a reducing agent includes reference to one or many such materials, and reference to exposure implies one or many such steps.

As used herein in relation to an identified property or circumstance, the term essentially implies a degree of deviation that is small enough not to create a measurable diminution of the identified property or circumstance. The exact degree of tolerance may in some cases depend on the specific context.

As used here, the term adjacent refers to the proximity of two structures or elements. In particular, elements that are indicated as adjacent can be either adjacent or connected. Such elements can also be close or adjacent to each other, without the need for contact with each other. The exact degree of proximity in some cases may depend on the specific context.

As used herein, hydrogenated products are those in which hydrogen is introduced either by the formation of hydrogen compounds, dissolution of hydrogen, or a combination of both mechanisms. Dissolved hydrogen exists as an interstitial element within the crystal lattice of a metal. Ti with dissolved hydrogen is called a solid solution of Ti with hydrogen. In contrast, hydride compounds are those in which hydrogen is chemically bonded to a corresponding metal (eg, titanium hydride, or the like). Fully hydrogenated titanium is known as titanium hydride with the formula TiH2. However, titanium hydride can also be less than fully hydrogenated, in which case the formula can be written as _{TiH2_x} .

As used herein, the term particulate is intended to mean fine powder or particulate products having a size of less than about 1 mm, and most often less than about 500 microns.

As used herein, numerous parts, structural elements, compositional elements, and/or materials may, for convenience, be presented in a general list. However, these lists should be interpreted as if each member of the list is individually identifiable as a separate and unique member. Thus, no individual member should be considered as essentially equivalent to any other member of the same list, based solely on its presentation in the general group, without indicating otherwise.

As used herein, the term at least one of is intended to be synonymous with the expression one or many of. For example, at least one of A, B, and C directly includes A only, B only, C only, or each of combinations.

As used here, the term about is used to give the permissibility of deviation and impression associated with a given term, indicator or meaning. The degree of flexibility for a particular variable can be easily determined by one skilled in the art. However, unless otherwise noted, the term about generally implies a tolerance of less than 2%, and most commonly less than 1%, and in some cases less than 0.01%. Note

- 3045179 of a particular value also clearly reveals the precision of that value such that about 4 would also include exactly 4. Moreover, all percentages represent weight percentage unless otherwise noted.

Concentrations, quantities and other numerical values may be presented here in range format. It should be understood that this format of ranges is for convenience and brevity only, and should be interpreted flexibly to include not only the numerical values clearly stated as the limits of the range, but also to include all individual numerical values or subranges falling within that range. as if each numerical value and subrange were clearly indicated. For example, a numerical value from about 1 to about 4.5 should be understood to include not only the specifically stated ranges from about 1 to about 4.5, but also to include individual numbers such as 2, 3, 4, and subranges such as from 1 to 3, 2 to 4, etc. The same principle applies to ranges indicating only one numerical value, such as less than about 4.5, which should be interpreted as including all of the above values and ranges. Moreover, this interpretation must be applied regardless of the width of the range or characteristics being described.

Any steps specified in any method or process in the claims may be performed in any order and are not limited to the order specified in the claims. Means plus function or step plus function limitations will only be used where, for a particular claim limitation, all of the following conditions are present in that limitation: a) the means for or step for is clearly stated and b) the relevant function is clearly provided. The structure, material or actions that support the function of the means for are specifically indicated here in the description. Accordingly, the scope of the invention should be determined only by the claims and their legal equivalents rather than by the descriptions and examples given herein.

With reference generally to FIG. 1, a method 100 for producing a dispersed titanium alloy product may involve producing 110 a mixture of composite dispersed oxides. The mixture of composite dispersed oxides may include TiO ₂ powder and powder of at least one alloying element. The method 100 may also include co-reduction 120 of a mixture of composite particulate oxides using a metal reducing agent in a wholly or partially hydrogen atmosphere at a reduction temperature for a reduction time sufficient to form a hydrogenated titanium alloy product. After co-reduction 120, heat treatment 130 of the hydrogenated titanium alloy product may be performed. The heat treatment step may be carried out under a hydrogen atmosphere and at a heat treatment temperature sufficient to reduce pore size and specific surface area to form a heat treated hydrogenated titanium product. The method 100 may further include deoxygenating 140 the thermally treated hydrogenated titanium product to reduce the residual oxygen content to less than 0.3 wt.% (or often less than 0.15 wt.%) to form particulate deoxygenated hydrogenated titanium product. In some cases, the hydrogenated titanium product may desirably provide storage and long-term stability. However, when preparing the final titanium product, a dehydrogenated product may be desirable. Accordingly, method 100 may optionally include dehydrogenating 150 the deoxygenated hydrogenated titanium product to form a particulate titanium alloy product. Each of these stages is discussed in more detail below.

As the titanium source, the TiO2 powder may include any source of titanium dioxide powder. The source of powdered titanium dioxide can be obtained from any suitable source, such as natural materials isolated from the earth and/or pre-processed materials such as natural rutile (TiO ₂ ), ilmenite (FeTiO ₃ ), and leucoxene (a product of the metaphorical alteration of titanium-containing minerals ). Such materials may contain varying amounts of titanium dioxide. Raw titanium ore as a starting material can be heated to increase the percentage of titanium. Typically, the raw ore may have a titanium oxide content of from about 50 to about 65 weight percent. Although other methods can be used, the raw titanium ore can be subjected to carbothermal reduction to form TiO ₂ slag. Such low-grade TiO ₂ slag can often contain about 80 wt.% titanium oxide, although levels of about 70 to 90 wt.% can be achieved by varying feeding and processing conditions. Specific conditions may vary, however, as a general principle, such carbothermic reduction may involve heating to a temperature of from about 1000 to 1600°C. The result is TiO ₂ slag, which, in addition to TiO ₂ , includes other reaction products or impurities such as pig iron. The enriched slag (UGS) may have a TiO ₂ content of from about 92 to about 95 wt.%. Other known hydrometallurgical or chemical metallurgical processes can be used to produce highly concentrated raw material with a TiO2 content of over 80 wt.% and in some cases up to 99 wt.%.

However, the TiO ₂ powder may include impurities, but at least 50% and often greater than 80%, most often greater than about 95% TiO ₂ , and in some cases greater than about 99 weight percent TiO ₂ , and V

- 4 045179 other cases over 99.5 wt.% TiO2. TiO2 powder source can be purchased in almost any particle size. Commonly available commercially available pure TiO2 powder can often have particle sizes of about 0.2 to 0.3 microns, which may be too fine for the reliable processing described here. However, the TiO ₂ powder source may have particle sizes ranging from about 50 nm to about 500 μm, often from about 1 to about 100 μm, in some cases from 3 to 80 μm, and often from 20 to 60 μm, and in some cases about 30 microns. For example, a source of TiO ₂ powder sold as a pigment is formed with a size of less than 300 nm. Such powder can be used as a source of material for this method, but may first be made by coarser granulation and sintering. The resulting Ti or TiH ₂ metal particles have average particle sizes greater than 20 microns (μm), and often greater than 30 microns (μm), to avoid excessive oxygen entrainment during processing and storage. This source particle size can be adjusted by grinding, sintering, agglomeration, and the like, as is discussed more fully below. Similarly, the source of TiO ₂ powder may have a specific surface area of 0.1 to 100 m ² /g and in some cases from 30 to 50 m ² /g (as measured by the BET (Brunauer-Emmett-Teller) method). In particular, during processing, the TiO ₂ powder may be temporarily converted into intermediate titanium oxides such as, but not limited to, Ti ₂ O ₃ , Ti ₅ O ₉ , and the like. Such intermediate titanium oxides may also be suitable for use in this method.

As an additional particulate source, the composite of at least one alloying element powder may include elemental metals, metal oxides, metal hydrides, or combinations thereof. In one case, the powder of the at least one alloying element is a powdered metal oxide. Non-limiting examples of suitable powdered metal oxides may include Al ₂ O ₃ , V ₂ O ₅ , CuO, MnO, V ₂ O ₃ , Fe ₂ O ₃ , Nb ₂ O ₅ , ZrO ₂ , MoO ₃ , MoO ₂ , Cr ₂ O ₃ , SnO ₂ , SiO ₂ , Ta ₂ O ₅ , CoO, WO ₃ , NiO, and their combinations, including oxides of elements from the above list in variable valence states. For example, V ₂ O ₃ may provide better wettability and lower residence times or temperatures than V ₂ O ₅ during sintering (ie, homogenization steps).

Alternatively, or in addition, the at least one particulate alloying element may include an elemental metal. Non-limiting examples of suitable elemental metals include Al, Mo, V, Nb, Ta, Fe, Cr, Mn, Co, Cu, W, Zr, Sn, Ni, Si, and combinations thereof. In one example, the at least one powdered alloying element may include a metal hydride. Non-limiting examples of suitable metal hydrides include aluminum hydride, vanadium hydride, niobium hydride, tantalum hydride, zirconium hydride, silicon hydride, and combinations thereof.

In one example, the powdered alloying element may also include a mixture of oxides and elemental powder. However, the choice of powdered alloying elements may depend on the desired titanium alloy product. Appropriate molar ratios of elemental metals in the raw material powder can be selected to obtain the desired alloy. Non-limiting examples of titanium alloys that can be prepared include Ti-6Al-4V, Ti2.5Cu, Ti-8Mn, Ti-3Al-2.5V, Ti-5Al-2.5Fe, Ti-6Al-7Nb, Ti-13Nb -13Zr, Ti-15Mo-5Zr, Ti-10V-2Fe-3Al, Ti-8V3Al-6Cr-4Mo-4Zr, Ti-6Al-2Sn-4Zr-2Mo-0.1Si, Ti-15Mo-3Al-2.7Nb -0.25Si, Ti-15Mo-2Sn-4Zr-4Mo-2Cr-1Fe, and the like.

Optionally, the metal oxide powder or composite powder mixture may be prepared prior to co-reduction such as pre-reduction, purification, particle coarsening, homogenization, and the like. For example, the powdered metal oxide may be pre-reduced to a different oxidation state, separate from the co-reduction step. In one case, V ₂ O ₅ can be reduced to V2O3.

In some cases, producing a mixture of composite dispersed oxides may involve reducing the content of impurities. For example, TiO2 powder and/or alloying element powders may be pre-leached to remove impurities that are undesirable (ie, interfere with processing or detract from the value of the final product). Non-limiting examples of impurities that may be removed include silicon, silica, aluminum, chromium, vanadium, sodium, iron, magnesium, and the like. The impurities may be reduced or removed by any suitable method, such as, but not limited to, leaching (eg, NaOH solution), electrolysis, precipitation, leaching, and the like. For example, depending on the quality of the starting material and the desired quality of the final alloy product, silicon may be removed by acid dissolution or precipitation. In some cases, the desired silicon content in the final titanium alloy product may be less than about 0.1 wt.%, and in some cases less than 0.04 wt.%. Accordingly, an optional desilication step may be performed to further reduce the silicon content. As a general principle, it may be desirable to reduce the silicon content of the solids to less than 0.04 wt.% and often less than 0.015 wt.%.

In other cases, as part of the pre-reduction, it may be desirable to adjust the particle size to a desired target size. In one specific example, a mixture of composite dispersed oxides can be aggregated by grinding, homogenizing, drying and grinding, debinding and sintering, and crushing. Grinding the TiO2 powder and at least one alloying element powder can form an oxide raw material powder having a predetermined particle size. Grinding can be performed to achieve a target particle size of 100 to 1000 nm, and most commonly 200 to 600 nm.

Homogenization of the oxide raw material powder can form a composite homogeneous agglomerate. Homogenization can be accomplished by mixing the oxide raw material powder in a mixture of water and a suitable suspending agent. A suspending agent may serve to suspend the particles in water to provide more uniform mixing during subsequent drying. Non-limiting examples of suspending agents may include polyethylene glycol (PEG), polyvinyl alcohol (PVA), and the like. The weight ratio of the oxide raw material powder to water can be varied in any functional amount to ensure uniform mixing of the powders. However, as a general principle, the weight ratio of water to raw powder may be from about 0.5:1 to 3:1, from 0.8:1 to 1.5:1, and in some cases about 1:1. The suspending agent may also be added in an amount sufficient to create a homogeneous mixture of powders. As a general principle, the suspending agent may comprise from 0.5 to 5% by weight of the oxide mixture. The water may optionally be preheated to completely and quickly dissolve the PEG or other suspending agents.

By drying and grinding the composite homogeneous agglomerate, a homogenized composite oxide powder can be obtained. Drying can be carried out at temperatures above the water evaporation temperature, while grinding can be carried out to separate the agglomerate. In general, comminution may involve only releasing agglomerated particles rather than reducing particle size. As a general principle, the sizes of the dried and ground powders can range from about 50 to 200 mesh, and in one example be 100 mesh.

By removing the binder material and sintering the homogenized composite oxide powder, a sintered composite oxide material can be obtained. Debinding and sintering can be performed at atmospheric pressures, while debinding and sintering are typically carried out in multiple stages, for example, a low temperature debinding stage and a high temperature debinding stage. For example, the debinding temperature may typically range from about 100°C to about 400°C. Once removal of the binder material is complete, the mixture can be heated to a sintering temperature of about 1000 to 1800°C. A sintering step can be carried out to enlarge the oxide particles. Debinding and sintering can be accomplished in a single heating step, although typically multiple heating steps can be used. Debinding and sintering times can typically be from about 2 hours to about 24 hours, and most typically from about 3 hours to 8 hours. Likewise, sintering can typically be carried out for a time from about 2 hours to about 8 hours Intermediate heating steps to reach debinding and sintering temperatures, as well as cooling to room temperature, can also result in a cumulative debinding and sintering time of about 12 to 48 hours. In some cases, debinding and sintering may act as a step homogenization to improve the uniformity of distribution of Ti and alloy metal powder throughout the composite powder.

Sintering may also cause some agglomeration of the powder. As a result, a grinding step can be performed to separate the agglomerated powder. The sintered composite oxide powder may be in the form of agglomerated particles, each having different metal oxides physically associated with each other, or may be a mixture where each particle is a single metal oxide. Regardless, grinding the sintered composite oxide material results in the formation of a sintered homogenized composite oxide powder having an increased particle size relative to a given particle size. The increased particle size may vary, but is typically from about 0.5 μm to about 300 μm, and often from about 10 μm to about 250 μm, and in some cases from 25 μm to 50 μm. Such an increase in the particle size of the feed powder may reduce the likelihood of unwanted burnout, and otherwise stabilize the feed powder.

Co-reduction of the composite dispersed oxide mixture may involve exposing the mixture to a metal reducing agent in a hydrogen atmosphere at the reduction temperature to produce a hydrogenated titanium alloy product. Typically, a metal reducing agent in the form of a solid particulate material can be physically mixed with a mixture of composite dispersed oxides, and then heated to the reduction temperature. The metallic reducing agent may have a higher oxidation potential than titanium. The presence of hydrogen contributes to the destabilization of the Ti-O system and facilitates the reduction of the oxide mixture with a metallic reducing agent. After reduction, the reduced product is cooled from the reduction temperature to room temperature. Maintaining a hydrogen atmosphere during cooling will result in the formation of titanium hydride. The exact hydrogen content of a Ti alloy depends on the specific temperatures and the time spent at those temperatures. Typically, as the furnace cools, the titanium product will end up as titanium hydrides as products with 3-4 wt% hydrogen. In the co-reduction stage, a hydrogenated titanium alloy is formed as a product chemically separated from metal impurities. Chemically separated means that the titanium is not fused or chemically bonded with other metallic impurities other than alloying elements.

The metal reducing agent may be at least one of a magnesium reducing agent and a calcium reducing agent. In one example, the metal reducing agent is a magnesium reducing agent including Mg. Optionally, MgCl2 may be added and mixed to stimulate the reaction. In principle, the reduction reaction can only occur under the influence of Mg and H2. However, to improve the kinetic performance of the reaction rate, the reaction can be carried out in a molten salt environment. For example, MgCl2 can be used. At the reaction temperature, MgCl2 is in a molten state, which stimulates the reaction, but it does not participate in the reduction reaction. The reduction temperature for the magnesium metal reducing agent may typically be in the range of about 600°C to about 950°C, and most commonly from about 645°C to 800°C. The reducing agent may be present in a weight ratio of oxides to reducing agent from 1:1 to 1:5 and most commonly from about 1:1 to 1:2. Although described in more detail here, the metal reducing agent can be added in at least stoichiometric amounts, and in some cases up to 6 times the molar amount of Ti and alloying elements.

For example, FIG. 2 illustrates the relative co-reduction of certain oxides in stoichiometric amounts of Mg in hydrogen. Fig. 2B is a reproduction of FIG. 2A with the y-axis enlarged to show the ratios of hydrides and oxides in more detail. It should be noted that the amount of TiO increases significantly at temperatures higher than about 600°C. In addition, A1 is present as TiAl at temperatures from about 500 to 800°C, while V is present as elemental V at all temperatures. Likewise, FIG. 2C illustrates the relative co-reduction in hydrogen of certain oxides with 1.2 times the stoichiometric ratio of Mg. It should be noted that the amount of TiO is significantly reduced at temperatures above 700°C, compared to the amount of TiO in a system with 1-fold stoichiometric amounts of Mg (Fig. 2A). Fig. 2D illustrates the relative co-reduction in hydrogen of certain oxides with 1.5 times the stoichiometric amounts of Mg. The amount of TiO decreases further above 700°C with this 1.5-fold increase in stoichiometric Mg content compared to FIG. 2A and B. FIG. 2B, C and D show the effect of the amounts of Mg on the amount of TiO at temperatures above 700°C, for example, the more TiO remains, the less complete the reduction. As a point of comparison, FIG. 2E and 2F illustrate the relative co-reduction in argon of these oxides at 1.2- and 1.5-fold stoichiometric ratios. It is noteworthy that the use of argon instead of hydrogen results in a more temperature-independent variation, and creates more TiO at elevated temperatures, compared to co-reduction in hydrogen.

Alternatively, the metal reducing agent may be one or both of Ca and CaH ₂ . Calcium can be effective, although the reduction temperature must be from about 750 to 850°C, which is generally higher than for Mg as reducing agents. Regardless of the reducing agent chosen, the reduction temperature may be sufficient to maintain the metal reducing agent in a molten state during co-reduction (e.g., 649°C for Mg, 714°C for MgCl ₂ , 842°C for Ca, and 772°C for CaCl ₂ ) .

In yet another alternative, molten salts can be used to facilitate the co-reduction process since the kinetic rates of the reactions can be improved by the use of the liquidized salt. More specifically, molten salts have very high conductivity and facilitate electron transfer during the reduction reaction. Molten salts also act to help dissolve by-products such as MgO or CaO during the reduction process. In addition to monometallic chloride, binary salts such as MgCl ₂ +NaCl, MgCl ₂ +KCl, and MgQ ₂ +CaCl ₂ can be used in conjunction with other binary and ternary salt mixtures.

Regardless of the specific metal reducing agents, the concentration of hydrogen gas can be maintained during co-reduction so as to form a hydrogenated titanium alloy as a product. Co-reduction generally involves three stages, that is, an initial heating stage, a holding stage and a cooling stage. Initial heating can most often be done from about room temperature to reduction temperature. An inert gas such as argon may be used during the initial heating, although hydrogen could be used. In one example, co-reduction is carried out by heating to the reduction temperature under an inert gas atmosphere, and then creating a hydrogen atmosphere when about 10% hydrogen is reached.

- 7 045179 ranks of recovery temperature. Reduction temperatures from about 700 to about 800°C may be applicable depending on the selected reducing agents, including mixtures of reducing agents. The reduction temperature can be maintained for a desired holding time sufficient to co-reduce the titanium oxide and metal oxides. Holding times may vary, but are typically 4 to 24 hours, in some cases 4 to 18 hours, and most commonly 6 to 8 hours. The co-reduction step can be carried out sufficiently until the oxygen content of the hydrogenated titanium alloy is reached. as a product at a level of less than about 3 wt.% and most often less than about 2 wt.%, and in some cases about 1 wt.%. Most of this residual oxygen is in the form of dissolved oxygen (i.e., solid solution) in the metal alloy.

The thermodynamic driving force for reduction of TiO ₂ using Mg can be significantly increased in the presence of hydrogen. Hydrogen acts as a temporary destabilizer (eg, of the alloying element), promoting the reduction of TiO ₂ and alloying metal oxides during the reduction stage. The presence of hydrogen during deoxygenation may allow oxygen removal by Mg (ie, or Ca) until the oxygen content is sufficiently low (ie, <0.2 wt%). However, the hydrogen content of Ti is a function of temperature. For example, at relatively high temperatures (>400°C) Ti contains hydrogen, but it is not uniformly present as a hydride. Rather, hydrogen can be dissolved in Ti to some extent without forming a hydride, that is, TiH ₂ or TiH ₂ - _x . Although pressures may vary, recovery pressure is usually approximately atmospheric, and typically within about 100% atmospheric pressure.

In addition, the formation of TiH ₂ rather than Ti metal is advantageous because titanium metal is more prone to form alloys with other elements such as Fe, which can be difficult to remove. In addition, TiH ₂ has completely unique chemical properties. It is insoluble in water, resistant to mildly acidic solutions, and provides minimal or no solubility to other impurities in TiO2 enriched material. In addition, TiH ₂ is not susceptible to oxygen scavenging compared to metallic Ti, which helps keep oxygen levels low in the final metal product. It should be noted that the insolubility of TiH ₂ in water is due to its kinetic passivation by water. At the reduction temperature, which is a high temperature in this process, the hydrogen content of Ti is relatively low. The alloy (that is, Ti plus alloying metals) is a solid solution of hydrogen in Ti. At this temperature, doping can occur. However, after cooling the material in a hydrogen atmosphere, as the hydrogen content of Ti increases, it will gradually transform into TiH ₂ . Once it forms TiH ₂ , it will be more difficult than if it were Ti metal to be dissolved in any of the many alloying elements. Accordingly, this method provides alloy control, where TiH2 acts as a limiting factor for alloying to those metals that must be intentionally introduced. These properties result in a condition in which the direct reduction product of purified TiO2 can be subsequently leached to remove other contaminants to separate and purify the TiH2. Although the chemical stability of TiH2 makes it possible to separate it from other impurities, if the particle size of _TiH2 is too small, for example on the submicrometric scale, it can also become soluble in those solutions.

In one example, the cooling step may include a hydrogen atmosphere, wherein an inert gas is optionally included. The concentration of the optional inert gas can be varied to carefully support hydrogenation and formation of TiH ₂ . Thus, after reduction, heat treatment and deoxygenation, the titanium alloy material can be cooled. During cooling, the equilibrium hydrogen content of Ti will increase with decreasing temperature, at the same pressure (eg 1 atm (0.1 MPa) and hydrogen gas flow). Once the product has been completely cooled to room temperature, the titanium is mostly in the hydride state.

Notably, co-reduction tends to form a porous material having an increased surface area. Although results may vary, hydrogenated titanium alloy as a product is particulate, which can have a specific surface area from 0.1 to 100 m ² /g and an average particle diameter from 1 to 100 microns. The size and morphology of the porous material is generally inherited by the hydrogenated alloy as a product formed by reduction with Mg in hydrogen.

After co-reduction, the hydrogenated titanium alloy product may include titanium alloy hydride, titanium hydride, alloying metal hydrides, pure elemental titanium, and other elemental alloying metals, while also including MgO as a by-product of co-reduction along with unreacted MgCl ₂ . MgO can be removed in a leaching step. For example, for leaching MgO and leaving a product enriched with hydrogenated

- 8 045179 titanium alloy, weak acids can be used, such as, but not limited to, dilute HCl, organic acids, HCl-HNO ₃ solution, acetic acid, ammonium chloride, and the like. A dilute aqueous solution of HCl is particularly effective in washing away MgO to provide a pure, purified hydrogenated titanium alloy product. Typically, the alloy product may have a titanium content of greater than about 95 wt.%. The resulting hydrochloric acid can be reused in the leaching process if necessary, and the remainder is sold.

After co-reduction, a heat treatment step may be carried out by heating to a heat treatment temperature to compact and coarse the powder, resulting in a reduction in pore size and a reduction in specific surface area. Heat treatment can also provide more uniform particle size and outer surface morphology. By way of example, heat treatment temperatures range from 700 to 1500°C and in some cases around 1100°C. In addition, a hydrogen atmosphere is used when the hydrogenated titanium alloy product is heated to a heat treatment temperature. During heat treatment, an inert gas may be used where the hydrogenated titanium alloy product is heated to the heat treatment temperature and then replaced with a hydrogen atmosphere (eg, optionally mixed with an inert gas). The heat treatment may include a time at the heat treatment temperature in a hydrogen atmosphere. Although conditions may vary, holding times of from about 1 minute to 10 hours, and most commonly from 1 to 4 hours, may be sufficient. Cooling after heat treatment may generally involve retaining at least sufficient hydrogen gas to maintain hydrogenation of the product as hydrogenated titanium alloy. Thus, in some cases, a mixture of hydrogen and an inert gas (eg argon) may be maintained during cooling, although hydrogen alone might also be used during cooling. A hydrogen atmosphere may also be maintained during cooling to control the hydrogen content of the refrigerated product. For example, excessively high hydrogen content can make the product brittle. At this stage, brittle material may be desirable so that it can be crushed into particles of a given size. After heat treatment, the particles can be bonded to each other to form an agglomerated bulk mass. To obtain a powdered product, it is desirable to be able to break down the bulk mass into a powder of the desired particle size. If hydrogen is not used during cooling, metallic Ti will be produced, which may be very difficult to turn into powder. Another benefit of forming a hydride after heat treatment is to prevent the material from trapping excessive amounts of oxygen. Some minor oxygen uptake is difficult to avoid, but such oxygen uptake should generally be kept to a minimum. As a general principle, the heat treatment step controls the hydrogen content of the heat treated powder to vary between a fraction of a small percentage, and often between 0.5 and 3.0%, by adjusting the hydrogen concentration in the hydrogen atmosphere. In some cases, hydrogenated titanium alloy powder with a small amount of hydrogen content (eg, 1.0 to 2 wt.%) is beneficial for separating particles that may be partially bound during heat treatment.

Although coarsening by heat treatment may vary depending on materials and conditions, as a general rule, the coarsening powder may be in the form of an agglomerated porous particulate material that can be comminuted and optionally milled to the desired desired particle size. The particle size after crushing and grinding depends on the degree of grinding. The heat treatment closes the fine pores, achieving pore sizes of less than 10 microns (µm). Therefore, after grinding into powder with particle sizes in the range of 10-100 microns (μm), the individual particles are solid particles. Without heat treatment, without closing small pores, particles with sizes of 10-100 microns (µm) will be a finely porous sponge. In one example, the heat-treated hydrogenated titanium product is a coarse powder having a coarser specific surface area of from 0.01 to 0.5 m ² /g and in some cases from 0.08 to 0.15 m ² /g, and an average the particle diameter is from about 10 to about 1000 microns and in some cases about 300 microns, and often from about 50 to about 150 microns. The specific ideal size range will also depend on the intended use of the powder.

The size and uniformity of the dispersed powder can affect the quality and stability of subsequent processing. Thus, in some cases it may be desirable to grind the heat-treated hydrogenated titanium product to reduce agglomeration and form a dispersed powder having an average particle size of from 1 to 1000 microns, preferably 10-200 microns.

Although most of the oxygen present as oxides can be removed in the co-reduction step, residual oxygen may be present in the form of small amounts of oxides and some small amounts of dissolved oxygen in solid solution. Oxygen (O) has high solubility in titanium. In α-Ti, the solubility is up to 33.3 at.% (14.3 wt.%).

- 9 045179

Dissolved oxygen also has a detrimental effect on the mechanical properties of Ti alloys. Even 0.35 wt.% oxygen can significantly degrade the mechanical properties of titanium alloy products, especially ductility. Again, processing conditions may provide variable oxygen content results, the hydrogenated and heat treated titanium alloy as a product may still have from about 0.5 to about 3 wt.% oxygen, which is approximately the same as the oxygen content of the co-reduction product before heat treatment.

Accordingly, an additional separate deoxygenation step is carried out to further reduce the oxygen content. Deoxygenation can be accomplished by heating the heat-treated hydrogenated titanium product with a deoxygenation agent at the deoxygenation temperature, again under a hydrogen atmosphere. Non-limiting examples of suitable deoxygenating agents include Mg, MgH2, Ca and CaH2. Typically, deoxygenation can be stimulated by using molten salt as a deoxygenation medium to increase the kinetic rates of the reaction. Examples of molten salts may include, but are not limited to, MgCl2 and CaCl2. In yet another specific example, the molten salt may be a eutectic calcium halide salt comprising CaCl ₂ and at least one of KCl, LiCl and NaCl. Non-limiting examples of calcium salts may include CaCl2, CaBr2, CaI2, _CaCl2 -LiCl, CaCl2-KCl, CaCl2-MgF2-CaC^-LiF, CaC^-KF, CaC^-NaF, CaC^-NaBr, CaC^-LiBr, CaC^-KBr, CaCl2-NaI, CaCl2-LiI, CaCl2-KI, CaBr2-LiCl, CaBr2-KCl, CaBr2-MgF2, CaBr2-LiF, CaBr2-KF, CaBr2-NaF, CaBr2-NaBr, CaBr2-LiBr, CaBr2 -KBr, CaBr2-NaI, CaBr2-LiI, CaBr2-KI, CaI2-LiCl, CaI2-KCl, CaI2-MgF2, CaI2LiF, CaI2-KF, CaI2-NaBr, CaI2-LiBr, CaI2-KBr, CaI2-NaI, CaI2 -LiI, CaI2-KI, CaCl2-CaBr2, CaCl2-CaI2, CaCl2CaF2, CaBr2-CaI2, CaBr2-CaF2, CaI2-CaF2 and their combinations.

Typically, the calcium halide eutectic salt may be mixed with solid calcium in the presence of a titanium alloy product at temperatures below the melting point of calcium. The eutectic calcium halide salt can be formed by mixing calcium halide with an alkali metal halide and heating to a eutectic melting point below the melting point of calcium (ie, 842°C). Most often, the eutectic melting temperature may be at least 30°C below the deoxygenation temperature. In yet another specific example, the deoxygenating agent is Mg with MgCl ₂ as the molten salt medium. In deoxygenation, very small amounts of deoxygenating agent may also be used. For example, a ratio of thermally treated hydrogenated titanium product to deoxygenating agent of 1:0.2 to 1:1 may be suitable.

Typically, the deoxygenation temperature is sufficient to melt both the deoxygenation agent and the salt medium. The deoxygenation step can be carried out by heating the thermally treated hydrogenated titanium product under an inert gas atmosphere to a level within about 10% of the deoxygenation temperature, and then maintaining a hydrogen atmosphere during the deoxygenation holding time. As an example, the deoxygenation temperature may be from 650 to 800°C. Typically, the deoxygenation temperature can be sufficient to melt the deoxygenating agent and any salt as a molten salt medium, while also providing sufficient thermodynamic driving force for the reaction. However, deoxygenation may have the effect of reducing the residual oxygen in the deoxygenated hydrogenated titanium product to less than 0.2 wt.% and in some cases to less than 0.15 wt.%. In addition, the deoxygenated hydrogenated titanium product may often have a reduced surface area compared to the heat treated hydrogenated titanium product. In one example, the reduced specific surface area is from 0.05 to 0.5 m ² /g.

From a thermodynamic point of view, there is a limit for minimizing oxygen in Ti using Mg (without hydrogen) at elevated temperatures, such as ~1.5 wt.% at 600°C. In addition, deoxygenation of titanium requires diffusion of oxygen atoms within the titanium (when the oxygen level is less than 14.3 wt.%). When deoxygenation of titanium is carried out at temperatures above ~900°C, titanium undergoes a transformation from a hexagonal close-packed (HCP) to a body-centered cubic (BCC) crystal structure. In the latter structure, oxygen diffusion becomes relatively more active. Before the titanium transformation temperature is reached, the diffusion rate of oxygen is low; however, after transformation into the BCC structure at a high temperature above the transformation temperature, the movement of atoms occurs more than 100 times faster than in the LCP structure.

Calcium is one option for further minimizing oxygen from ~2 wt.% to less than 0.2 wt.% at high temperature. In one example, Ca metal may be mixed with titanium powder and heated to an elevated deoxygenation temperature. As a general principle, temperatures from about 500 to about 1000°C may be suitable. In one aspect, CaH2 may be used as the reducing agent. CaH2 is able to minimize the oxygen content of Ti to less than 0.2 wt%.

- 10 045179

Thus, in one example, a hydrogenated and heat-treated titanium alloy powder produced by a magnesium or magnesium hydride co-reduction process may be mixed with CaH2 or CaH2/CaCl2 and heated to a temperature higher than the temperature of the magnesium or magnesium hydride co-reduction process and held for a sufficient period of time to ensure that any residual oxygen contained in the titanium or titanium hydride powder is removed. The unreacted CaH2, CaCl2 and the resulting CaO in the product of the _CaH2 co-reduction process can then be washed away to produce a deoxygenated hydrogenated titanium alloy powder with minimized residual oxygen.

Optionally, the method may further comprise removing residual metal reducing agent and corresponding reducing agent oxides from the hydrogenated titanium alloy product or the thermally treated hydrogenated titanium product prior to deoxygenation. Deoxygenation may also result in the formation of CaO or MgO. As a result, the deoxygenating agent and residual CaO or MgO can be removed by leaching after deoxygenation. For example, leaching may be carried out as previously described for the removal of such materials after co-reduction or to obtain raw material powders.

After deoxygenation, the alloy powder can be stored in hydride form because the hydride minimizes oxygen uptake during storage compared to non-hydride forms. Thus, when the alloy powder is ready for use, the agent powder can be dehydrogenated to remove hydrogen (ie, including hydride and residual dissolved hydrogen), typically to a content of less than about 60 ^ppm .

When a non-hydrogenated alloy product is desired, dehydrogenation may involve heating the deoxygenated hydrogenated titanium product in a hydrogen-free atmosphere sufficient to displace hydrogen from the deoxygenated hydrogenated titanium product to form a titanium alloy product having a hydrogen content of less than about 100 ^ppm . Dehydrogenation can usually be carried out at temperatures from 400 to 800°C. Dehydrogenation can usually preserve both pore size and specific surface area.

Advantageously, the method eliminates electrolysis, chlorination and reduction of titanium chloride. The methods also avoid melting titanium oxides, metal oxides, titanium or metals during execution of the method (ie, reduction, heat treatment, deoxygenation, dehydrogenation, etc.). As such, the method can be carried out under completely solid state conditions.

In addition, titanium alloy as a product can be used as a starting material for the VAR process. More specifically, instead of introducing both Ti sponge and alloy into the VAR furnace, titanium alloy as a product can be directly introduced as the only input material. The titanium alloy product may similarly be used in other solid state alloying processes, such as, but not limited to, plasma smelting, electron beam smelting, and the like.

In accordance with the above principles, the method may alternatively include the introduction of alloying metals after the reduction of titanium oxides. For example, a method of producing a dispersed titanium alloy product may include preparing a mixture of dispersed oxides including titanium oxide powder. The mixture of dispersed oxides can be reduced using a metal reducing agent in a hydrogen atmosphere at the reduction temperature for a reduction time sufficient to form a hydrogenated titanium product. At least one alloying element may be introduced into the hydrogenated titanium product to form a composite hydrogenated titanium product. The hydrogenated titanium composite product may be heat treated under a hydrogen atmosphere and at a heat treatment temperature to reduce pore size and specific surface area to form a heat treated hydrogenated titanium alloy product. The heat-treated hydrogenated titanium alloy product may be deoxygenated to reduce residual oxygen to less than about 0.3 wt.% to form a deoxygenated hydrogenated titanium product. Optionally, the deoxygenated hydrogenated titanium product can be dehydrogenated to form a titanium alloy product, wherein the deoxygenated hydrogenated titanium product and the titanium alloy product are dispersed. Each of these steps, materials and conditions can be performed using the instructions and principles set forth above regarding joint recovery, although some performance and benefits may be lost or different.

Typically, the at least one powdered alloying element is an elemental metal. Likewise, in some cases, the introduction and heat treatment steps are performed simultaneously, although the alloying metals may be introduced immediately prior to heat treatment.

Example 1.

TiO2 powder in the form of a nano-sized pigment was obtained from Kronos. Al2O ₃ powder with a particle size of less than 1 μm and 99.9% purity was obtained from Alfa Aesar. V2O5 powder,

- 11 045179 having 99.6% purity and a particle size of -10 mesh, was purchased as an industrial product from Alfa Aesar. The V ₂ O ₅ powder was ground for 12 hours to obtain particles with a size of less than 1 μm. The three starting powders were homogenized to form a homogeneous powder mixture by mixing the composite powder into a 1.0% aqueous PEG solution at a water to powder weight ratio of 1:1. It should be noted that the starting powders can be introduced into the solution separately or in the form of a composite mixture. The first batch included 600 g of TiO ₂ , 45.3 g of Al ₂ O ₃ and 28.6 g of V ₂ O ₅ . The mixture was then stirred for 2 hours to obtain a homogeneous mixture. The wet mixture was dried in a tray and ground to about 100 mesh. The dried material was then heated to 700°C for about 2 hours to remove binding materials, and then heated (at a rate of 10°C/min) to a temperature of about 1200°C for about 4 hours to partially sinter the powder, as shown in FIG. . ZA and ZV, with the formation of an agglomerated powder of composite particles. The stage of removing binding materials and sintering was carried out in an argon atmosphere. The titanium oxide and alloying oxide particles bonded to each other to form larger composite particles with a broad size distribution (e.g., average particle size of 128.8 μm, standard deviation of 0.13, and BET specific surface area of 0.85 m ² / G). Energy dispersive X-ray spectroscopy (EDS) analysis of composite particles is shown in Table. 1.

Table 1. EDS analysis of composite particles

Element Weight.% At% ABOUT 34.31 60.06 A1 03.57 03.70 Ti 59.39 34.73 V 02.74 01.51

Then, the agglomerated composite particle powder was mixed with a mixture of Mg and MgCl ₂ as a reducing agent, and heated from room temperature under an argon atmosphere to a reduction temperature of 750°C. The materials were mixed with a mass ratio oκcid:Mg:MgCl ₂ 1:0.66:1. The argon atmosphere was then replaced with hydrogen and the temperature was maintained for 12 hours to restore the alloy powder. The reduced powdered alloy was then cooled to room temperature in pure hydrogen or a mixture of hydrogen and argon to maintain hydrogenation of the powder. Fig. 3D and 3D illustrate a hydrogenated and reduced alloy powder having most of the oxides reduced and leaving a porous morphology. The oxygen content after co-reduction was 1.92 wt.% (A1).

The hydrogenated and reduced powdered alloy was then heated under argon from room temperature to a temperature of about 1100°C, at which point the argon was replaced by a hydrogen atmosphere, and held for 3 hours as a heat treatment step to close the pores. Then the thermally treated powder was cooled to room temperature in a mixture of argon and hydrogen or in pure hydrogen. Fig. 3E and 3F illustrate a heat-treated and coarsened powdered alloy. The resulting powdered alloy had an average particle size of 96.85 μm and a specific surface area of 0.14 m ² /g.

Then the heat-treated powdered alloy was subjected to deoxygenation by mixing with Mg and MgCl ₂ as a deoxygenating agent, in a mass ratio of powdered cnnaB:Mg:MgCl ₂ 1:0.2:0.3. The mixture was heated from room temperature to 740° C. under argon and then maintained at this temperature in a hydrogen atmosphere for 4 hours. The hydrogen concentration was maintained at 1 to 4 wt.% during cooling to obtain a deoxygenated hydrogenated alloy powder as shown in fig. 3G and ZN. The resulting deoxygenated alloy powder had an average particle size of 79.52 μm and a specific surface area of 0.21 m ² /g. It should be noted that the particle size and morphology remained essentially the same before and after deoxygenation. Table 2 shows the changes in average particle size and specific surface area at various stages of alloy production. The results show that the average particle size is reduced due to heat treatment and deoxygenation. This is due to the removal of oxygen from the oxides and compression of the particles during heat treatment. The specific surface area is sharply reduced after heat treatment because the pores are closed due to heat treatment. Since titanium exhibits a high affinity for oxygen, reducing the specific surface area may also help reduce the amount of oxygen attached to the titanium surface.

- 12045179

Table 2. Average Particle Size, BET Specific Surface Area, and Oxygen ____________________ at Various Stages _____________

Stages After consolidation sintering After heat treatment After deoxygenation roving The average size particles 128.8 µm 96.85 µm 79.52 µm Specific area surfaces according to BET 0.85 m ² /g 0.14 m ² /g 0.16 m ² /g Oxygen,% 1.92 (after restoration) 2.37 0.25

Example 2.

The conditions of Example 1 were essentially repeated with a 10% increase in weight of the addition of starting alumina. The three starting powders were homogenized to form a homogeneous powder mixture by mixing the composite powder into a 2% by weight aqueous PEG solution at a water to powder weight ratio of 1:1. The first batch included 600 g TiO ₂ , 49.8 g Al ₂ O ₃ , and 28.6 g V ₂ O ₅ . The mixture was then stirred for 2 hours to obtain a homogeneous mixture. The wet mixture was dried in a tray and ground to about 100 mesh. The dried material was then heated to 700°C for about 2 hours to remove binding materials and then heated (at a rate of 10°C/min) to a temperature of about 1200°C for about 4 hours to partially sinter the powder, as shown in FIG. 4A and 4B to form an agglomerated powder of composite particles. The stage of removing binding materials and sintering was carried out in an argon atmosphere.

Then, the agglomerated composite particle powder was mixed with a mixture of Mg and MgCl ₂ as a reducing agent, and heated from room temperature under an argon atmosphere to a reduction temperature of 750°C. The materials were mixed with a mass ratio of oxide:Mg:MgCl ₂ 1:0.66:1. The argon atmosphere was then replaced with hydrogen and the temperature was maintained for 12 hours to restore the alloy powder. The reduced powdered alloy was then cooled to room temperature in pure hydrogen or a mixture of hydrogen and argon to maintain hydrogenation of the powder. Fig. 4C illustrates a hydrogenated and reduced alloy powder having most of the oxides reduced and leaving a porous morphology. The oxygen content after co-reduction was 2.48 wt.% (A2).

The hydrogenated and reduced alloy powder was then heated under argon from room temperature to a temperature of about 1100°C, at which point the argon was replaced by a hydrogen atmosphere, and held for 6 hours as a heat treatment step to close the pores. Then the thermally treated powder was cooled to room temperature in a mixture of argon and hydrogen or in pure hydrogen. Fig. 4D and 4E illustrate a heat-treated and coarsened powdered alloy. The resulting powdered alloy was more difficult to grind than the A1 powder due to the longer holding time.

Then the heat-treated powdered alloy was subjected to deoxygenation by mixing with Mg and MgCl ₂ as a deoxygenating agent, in a mass ratio of powdered alloy: Mg: MgCl ₂ 1: 0.2: 0.3. The mixture was heated from room temperature to 740° C. under argon, and then maintained at this temperature in a hydrogen atmosphere for 4 hours. The hydrogen concentration was maintained at 1-4 wt.% during cooling to obtain a deoxygenated hydrogenated alloy powder as shown in fig. 4F and 4G. The resulting deoxygenated alloy powder was more uneven than A1 powder and had an average particle size of 177.83 μm and a specific surface area of 0.14 m ² /g. It should be noted that the particle size and morphology remained essentially the same before and after deoxygenation. Table 3 shows changes in the oxygen content of the powdered alloy at various stages of alloy production.

_____Table 3. Oxygen content at various stages_____

Stages After recovery After heat treatment After deoxygenation roving Oxygen,% 2.48 2.76 0.15

Example 3.

The conditions of Example 1 were essentially repeated with a 10% increase in weight of the addition of starting alumina. The three starting powders were homogenized to form a homogeneous powder mixture by mixing the composite powder into a 2% by weight aqueous PEG solution at a water to powder weight ratio of 1:1. The first batch included 600 g TiO ₂ , 49.8 g Al ₂ O ₃ , and 28.6 g V ₂ O ₅ . The mixture was then stirred for 2 hours to obtain a homogeneous mixture. The wet mixture was dried in a tray and ground to about 100 mesh. The dried material was then heated to 700°C for about 2 hours to remove binding materials and then heated (at a rate of 10°C/min) to a temperature of about 1200°C for about 4 hours to partially sinter the powder as shown in fig. 5A and

5B, to form an agglomerated powder of composite particles. The stage of removing binding materials and sintering was carried out in an argon atmosphere.

Then, the agglomerated composite particle powder was mixed with a mixture of Mg and MgCl ₂ as a reducing agent, and heated from room temperature under an argon atmosphere to a reduction temperature of 750°C. The materials were mixed with a mass ratio of oxide:Mg:MgCl ₂ 1:0.66:1. The argon atmosphere was then replaced with hydrogen, and the temperature was maintained for 12 hours to restore the alloy powder. The reduced powdered alloy was then cooled to room temperature in a mixture of hydrogen and argon to maintain hydrogenation of the powder. Fig. 5C and 5D illustrate a hydrogenated and reduced alloy powder having most of the oxides reduced and leaving a porous morphology. The oxygen content after co-reduction was 1.28 wt.% (A3).

The hydrogenated and reduced powdered alloy was then heated under argon from room temperature to a temperature of about 1100°C, at which point the argon was replaced by a hydrogen atmosphere, and held for 3 hours as a heat treatment step to close the pores. Then the thermally treated powder was cooled to room temperature in a mixture of argon and hydrogen. Fig. 5E and 5F illustrate a heat-treated and coarsened alloy powder. The resulting powdered alloy was more difficult to grind than the A1 powder due to the moderately high holding temperature. Thus, a lower holding temperature and a longer holding time could be used.

Then the heat-treated powdered alloy was subjected to deoxygenation by mixing with Mg and MgCl ₂ as a deoxygenating agent, in a mass ratio of powdered alloy: Mg: MgCl ₂ 1: 0.2: 0.3. The mixture was heated from room temperature to 740°C under argon and then maintained at this temperature in a hydrogen atmosphere for 4 hours. The hydrogen concentration was maintained at 1 to 4 wt.% during cooling to obtain a deoxygenated hydrogenated alloy powder as shown in FIG. 5G and 5H. The resulting deoxygenated alloy powder was more uneven than A1 powder and had an average particle size of 145.32 μm and a specific surface area of 0.16 m ² /g. It should be noted that the particle size and morphology remained essentially the same before and after deoxygenation. Table 4 shows changes in the oxygen content in the powdered alloy at various stages of alloy production

Table 4. Oxygen content at various stages

Stages After recovery After heat treatment After deoxygenation roving Oxygen,% 1.28 1.34 0.15

Example 4yu

Again the same basic process as in Example 1 was repeated, except using V ₂ O ₃ as the vanadium oxide powder source instead of V ₂ O ₅ . The V ₂ O ₅ powder was ground to particles smaller than 1 μm, and heated in a hydrogen atmosphere at 600°C for 3 hours in the first stage, and then at 900°C for 5 hours in the second stage. The original 40 g of V ₂ O ₅ was previously reduced to 31.85 g of V ₂ O ₃ powder.

The three starting powders were homogenized to form a homogeneous powder mixture by mixing the composite powder into a 2% by weight aqueous PEG solution at a water to powder weight ratio of 1:1. The first batch included 600 g TiO ₂ , 45.3 g Al ₂ O ₃ , and 28.6 g V ₂ O ₃ . The mixture was then stirred for 2 hours to obtain a homogeneous mixture. The wet mixture was dried in a tray and ground to about 100 mesh. The dried material was then heated to 700°C for about 2 hours to remove binding materials and then heated (at a rate of 10°C/min) to a temperature of about 1200°C for about 4 hours to partially sinter the powder, as shown in FIG. 6A and 6B to form an agglomerated powder of composite particles. The stage of removing binding materials and sintering was carried out in an argon atmosphere.

Then, the agglomerated composite particle powder was mixed with a mixture of Mg and MgCl ₂ as a reducing agent, and heated from room temperature under an argon atmosphere to a reduction temperature of 750°C. The materials were mixed with a mass ratio of oxide:Mg:MgCl ₂ 1:0.66:1. The argon atmosphere was then replaced with hydrogen, and the temperature was maintained for 12 h to reduce the alloy powder. The reduced powdered alloy was then cooled to room temperature in a mixture of hydrogen and argon to maintain hydrogenation of the powder. Fig. 6C and 6D illustrate a hydrogenated and reduced alloy powder having most of the oxides reduced and leaving a porous morphology. The oxygen content after co-reduction was 1.16 wt.% (A3).

The hydrogenated and reduced powdered alloy was then heated under argon from room temperature to a temperature of about 1100°C, at which point the argon was replaced by a hydrogen atmosphere, and held for 2 hours as a heat treatment step to close the pores. Then the thermally treated powder was cooled to room temperature in a mixture of argon and hydrogen. Fig.

6E and 6F illustrate a heat-treated and coarsened alloy powder. The resulting powder was easier to grind than A2 powder.

Then the heat-treated powdered alloy was subjected to deoxygenation by mixing with Mg and MgCl ₂ as a deoxygenating agent, in a mass ratio of powdered alloy: Mg: MgCl ₂ 1: 0.2: 0.3. The mixture was heated from room temperature to 740° C. under argon and then maintained at this temperature in a hydrogen atmosphere for 10 hours. The hydrogen concentration was maintained at 1-4 wt.% during cooling to obtain a deoxygenated hydrogenated alloy powder. The resulting deoxygenated alloy powder had a final oxygen content of 0.15 wt.%, 6.88% aluminum and 4.82% vanadium, which were close to the specifications for the Ti-6Al-4V alloy.

Example 5.

The conditions of example 4 were repeated, with the exception of the preliminary reduction of V ₂ O ₅ included in the first stage at 600°C for 3 hours and the second stage at 900°C for 5 hours. Removal of binding materials and sintering were also carried out as in example 4 , except that the first batch (A5) was cooled under hydrogen and the second batch (A6) was cooled in an air atmosphere. Fig. 7A and 7B show sample A5 after sintering. Fig. 7C and 7D show sample A6 after sintering.

The powders were subjected to co-reduction as in Example 4. FIG. 7E shows the results of co-reduction of A5 having an oxygen content of 2.08%. Fig. 7F shows the results of co-reduction of A6 having an oxygen content of 5.04%.

The reduced powder was then heat treated as in Example 4, with the results for A5 and A6 shown in FIG. 7G and 7H respectively. These powders were then deoxygenated as in Example 4. FIG. 7I and 7J illustrate deoxygenated powders. The deoxygenated alloy powder A5 had an oxygen content of 0.087 wt.%, while the powder A6 had an oxygen content of 0.25 wt.%. The deoxygenated A5 alloy powder had an average particle size of 102.32 μm and a specific surface area of 0.11 m ² /g. The deoxygenated A6 alloy powder had an average particle size of 74.17 μm and a BET specific surface area of 0.35 m ² /g. The EDS analysis results also showed that the A1 and V contents of each of A5 and A6 were quite close to the target (i.e., 7.57 wt.% and 7.66 wt.% for A1, and 4.36 wt.% and 4.11 wt.% for V), with an aluminum content higher than the specified 6 wt.%.

Comparison

Table 5 shows oxygen content as a function of BET specific surface area for different batches. The results show that the oxygen content after deoxygenation in Ti-6Al-4V alloys increases with increasing BET specific surface area. These results also show that oxygen attached to the particle surface makes the largest contribution to the total oxygen content. The specific surface area can be maintained at <0.15 m ² /g to at least achieve the oxygen content after deoxygenation according to ASTM B299 (<0.15 wt.%).

Table 5. Oxygen content versus specific surface area ____________________ by BET in different batches ____________

Batch No. A1 A2 AZ A4 A5 Specific surface area ( ^m2 /g) 0.21 0.14 0.16 0.16 0.11 Oxygen content (wt.%) 0.26 0.15 0.15 0.15 0.087

The heat treatment step has a significant impact on the specific surface area. In this stage, the particles are activated to close the pores under the influence of heat. Higher temperatures and longer soak times are both effective in closing the pores. However, high temperature and long aging times can also cause caking and make powders harder to break down. To solve this problem, hydrogen was supplied during cooling to form TiHx, which decomposes relatively easily at room temperature.

Review of SEM images at various stages showed Al-rich regions and V-rich regions clearly detected after removal of binder materials and sintering of Ti, Al and V oxides. After reduction, the element distribution was more uniform for both alloying elements. However, Al and V enriched regions could hardly be detected after heat treatment and deoxygenation, which shows that homogenization of elements occurs throughout the entire alloy formation process. Similarly, line scanning was performed on a cross section of Ti-6Al-4V alloy powder after deoxygenation. Line scanning showed similar trends for each of the three elements towards a uniform distribution in the alloy particles.

Energy dispersive X-ray spectroscopy (EDS) analysis was also performed on deoxygenated samples A1, A2 and A3. Spectra were taken on the cross section of a standard sample.

Claims (30)

tsa Ti-6Al-4V alloy, and ten particles were selected for analysis and the particle-to-particle variation was determined. The results show that the particle-to-particle variation is in the range of 0.8 for A1 and 0.46 for V. The measured results for the content of A1 and V were 7.34 and 3.76%, separately, which is different from this composition , analyzed by ICP (inductively coupled plasma) method. Thus, in comparison with this composition, deviations of +13.2% for A1 and -4.0 for V apply to the measured samples. In this experiment, theoretical amounts of A1 (6%) and V (4%) were added for A1, and 10% more were added for A2 and A3 for contrast. The results of EDS analysis are given in table. 6. Table 6. Aluminum and vanadium content according to EDS Sample A1 (calibrated%) V (calibrated%) A1 6.15 3.04 A2 6.80 3.10 AZ 6.9 3.14 Standard (ASM4998) 5.5-6.5 3.5-4.5 The results show that the calibrated A1 is 6.15%, which is within the acceptable range. However, both A2 and A3 calibrated contain more aluminum than the acceptable upper limit. Thus, the theoretical value of Al ₂ O ₃ can be added with good results. The particle-to-particle variation of A1 and V is within an acceptable range within each batch, with all batches from A1-A3 showing good uniformity. The results also show that all three samples contain less vanadium than the desired lower limit. Accordingly, as described above, Examples A4 to A6 were processed using V ₂ O ₃ as a source of vanadium oxide powder at stoichiometric ratios. V ₂ O ₃ has a higher melting point (1970°C) than V ₂ O ₅ (690°C), which may reduce evaporation during debinding and sintering at 1200°C. Table 7 shows the EDS results for samples A4 to A6. Table 7. Aluminum and vanadium content according to EDS Sample A1 (calibrated%) V (calibrated%) A4 6.04 3.66 A5 6.21 3.45 Ab 6,I 4,I Standard (ASM4998) 5.5-6.5 3.5-4.5 These results showed that both aluminum and vanadium were within acceptable ranges. However, the particle-to-particle variation of vanadium within each batch was unacceptably high. This would appear to be the result of poor wettability of V ₂ O ₃ compared to V ₂ O ₅ , leading to an uneven distribution of elements among the particles. So 20 to 30% excess V ₂ O ₅ can be used in the composite powder to achieve good wettability and allow for some evaporation or loss during the pre-reduction steps. In some cases, an excess of 10 to 50% may also be suitable. The above detailed description introduces the invention with reference to specific exemplary embodiments. However, it will be understood that various modifications and changes may be made without departing from the scope of the present invention as set forth in the appended claims. The detailed description and accompanying drawings are to be considered as illustrative only and not as limiting, and all such modifications or changes, if any, are intended to fall within the scope of the present invention as described and set forth herein. CLAIM 1. A method for producing a product in the form of a dispersed titanium alloy, including obtaining a mixture of composite dispersed oxides, including titanium oxide powder and a powder of at least one alloying element, wherein the powder of at least one alloying element is a powder of at least one metal oxide, elemental metal and metal hydride, in addition, the metal oxide powder is selected from the group consisting of A2O3, V2O5, CuO, MnO, V2O3, Fe2O3, Nb2O ₅ , ZrO2, MoO3, MoO2, C^O3, SnO2, S1O2, Ta2Os , CoO, WO ₃ , MO and combinations thereof, wherein the elemental metal is selected from the group consisting of Al, Mo, V, Nb, Ta, Fe, Cr, Mn, Co, Cu, W, Zr, Sn, Ni, Si and their combinations; and wherein the metal hydride is selected from the group consisting of aluminum hydride, vanadium hydride, niobium hydride, tantalum hydride, zirconium hydride, silicon hydride and combinations thereof; co-reduction of a mixture of composite dispersed oxides using a metal reducing agent in a hydrogen atmosphere at a reduction temperature for a reduction time sufficient to form a product in the form of a hydrogenated titanium alloy; heat treating the hydrogenated titanium alloy product under a hydrogen atmosphere and at a heat treatment temperature to reduce pore size and specific surface area to form a heat treated hydrogenated titanium product; and deoxygenating the heat treated hydrogenated titanium product to reduce residual oxygen to less than 0.3 wt%. to form a deoxygenated hydrogenated titanium product. 2. The method according to claim 1, wherein the titanium oxide powder contains more than 80 wt.% titanium oxides. 3. The method according to claim 1, in which a mixture of composite dispersed oxides is obtained by grinding titanium oxide powder and a powder of at least one alloying element to form a raw oxide powder having a given particle size; homogenization of raw oxide powder with the formation of a composite homogeneous agglomerate; drying and grinding the composite homogeneous agglomerate to form a homogenized composite oxide powder; removing the binder materials and sintering the homogenized composite oxide powder to form a sintered composite oxide material and crushing the sintered composite oxide material to form a sintered homogenized composite oxide powder having an increased size of the powder material in relation to a given particle size. 4. The method according to claim 1, in which the titanium product is selected from the group consisting of Ti-6Al-4V, Ti2.5Cu, Ti-8Mn, Ti-3Al-2.5V, Ti-5Al-2.5Fe, Ti- 6Al-7Nb, Ti-13Nb-13Zr, Ti-15Mo-5Zr, Ti-10V-2Fe-3Al, Ti-8V3Al-6Cr-4Mo-4Zr, Ti-6Al-2Sn-4Zr-2Mo-0.1Si, Ti- 15Mo-3Al-2.7Nb-0.25Si, and Ti-15Mo-2Sn-4Zr-4Mo-2Cr-1Fe. 5. The method of claim 1, wherein the metal reducing agent is at least one of a magnesium reducing agent and a calcium reducing agent. 6. The method of claim 1, wherein the co-reduction further comprises a molten salt medium, wherein the reduction temperature is sufficient to melt both the metal reducing agent and the molten salt medium. 7. The method of claim 6, wherein the metal reducing agent is Mg and the molten salt medium is MgCl ₂ . 8. The method of claim 1, wherein the co-reduction is carried out by heating to the reduction temperature under an inert gas and then creating a hydrogen atmosphere after reaching about 10% of the reduction temperature. 9. The method of claim 8, wherein the co-reduction includes a cooling step that is maintained under a hydrogen atmosphere and which optionally includes an inert gas. 10. The method of claim 1, wherein the oxygen content of the hydrogenated titanium alloy product is less than about 0.2%. 11. The method of claim 1, wherein the hydrogenated titanium alloy product comprises TiH ₂ with alloying elements dissolved therein and, optionally, elemental titanium. 12. The method according to claim 1, wherein the method excludes electrolysis and chlorination. 13. The method according to claim 1, wherein the hydrogenated titanium alloy product is a powder having a specific surface area of 0.1 to 100 m ² /g and an average particle diameter of 1 to 1000 μm. 14. The method according to claim 1, in which the heat-treated hydrogenated titanium product is a compacted and coarsened powder having a small specific surface area from 0.01 to 0.5 m ² /g and an average particle diameter from 1 to 1000 μm. 15. The method according to claim 1, further comprising crushing the heat-treated hydrogenated titanium product to reduce agglomeration and form a dispersed powder having an average particle size from 10 to 1000 microns. 16. The method according to claim 1, in which deoxygenation is carried out by heating a heat-treated hydrogenated titanium product with a deoxygenating agent at the deoxygenation temperature and in a hydrogen atmosphere. 17. The method of claim 16, wherein the deoxygenating agent is at least one of Mg, MgH ₂ , Ca and CaH ₂ . 18. The method of claim 17, wherein the deoxygenating agent is Mg and MgCl ₂ is used as the molten salt medium. 19. The method of claim 16, wherein the weight ratio of the heat-treated hydrogenated titanium product to the deoxygenating agent is from 1:0.2 to 1:1. 20. The method of claim 16, wherein the deoxygenation temperature is sufficient to melt the agent and is also sufficient to melt the salt in the mixture. 21. The method according to claim 16, in which deoxygenation is carried out by heating the thermally treated hydrogenated titanium product in an inert gas atmosphere until about 20% temperature is reached - 17 045179 deoxygenation and then maintain a hydrogen atmosphere during the deoxygenation holding time. 22. The method of claim 16, further comprising removing residual metal reducing agent and corresponding reducing agent oxides from the hydrogenated titanium alloy product or from the thermally treated hydrogenated titanium product prior to deoxygenation. 23. The method according to claim 16, in which the deoxygenation temperature is from 650 to 800°C. 24. The method according to claim 1, wherein the residual oxygen in the deoxygenated hydrogenated titanium product is less than 0.15 wt.%. 25. The method of claim 1, wherein dehydrogenation is optional and the dehydrogenation comprises heating the deoxygenated hydrogenated titanium product in a hydrogen-depleted atmosphere sufficient to remove hydrogen from the deoxygenated hydrogenated titanium product to form a titanium alloy product having a hydrogen content of less than about 100 million ^-1 wt.%. 26. A method for producing a product in the form of a dispersed titanium alloy, including obtaining a mixture of composite dispersed oxides, including titanium oxide powder; reducing the mixture of dispersed oxides using a metal reducing agent in a hydrogen atmosphere at a reduction temperature for a reduction time sufficient to form a hydrogenated titanium product; introducing at least one alloying element into the hydrogenated titanium product to form a composite hydrogenated titanium product, wherein the powder of the at least one alloying element is at least one of a metal oxide powder, an elemental metal and a metal hydride, and further, wherein the powder the metal oxide is selected from the group consisting of Al ₂ O ₃ , V ₂ O ₅ , CuO, MnO, V ₂ O ₃ , Fe ₂ O ₃ , Nb ₂ O ₅ , ZrO ₂ , MoO ₃ , MoO ₂ , Cr ₂ O ₃ , SnO ₂ , SiO ₂ , Ta ₂ O ₅ , CoO, WO ₃ , MO and combinations thereof, wherein the elemental metal is selected from the group consisting of Al, Mo, V, Nb, Ta, Fe, Cr, Mn, Co, Cu , W, Zr, Sn, Ni, Si and their combinations; and wherein the metal hydride is selected from the group consisting of aluminum hydride, vanadium hydride, niobium hydride, tantalum hydride, zirconium hydride, silicon hydride, and combinations thereof; heat treating the composite hydrogenated titanium product under a hydrogen atmosphere and at a heat treatment temperature to reduce pore size and specific surface area to form a heat treated hydrogenated titanium alloy product and deoxygenating the heat treated hydrogenated titanium alloy product to reduce residual oxygen to less than 0, 3 wt.% to form a deoxygenated hydrogenated titanium product. 27. The method of claim 26, wherein the at least one alloying element powder is an elemental metal and the addition and heat treatment steps are performed simultaneously. 28. A method for producing a product in the form of a dispersed titanium alloy, including obtaining a mixture of composite dispersed oxides, including titanium oxide powder and at least one alloying element powder; co-reduction of a mixture of composite dispersed oxides using a metal reducing agent under a hydrogen atmosphere at a reduction temperature for a reduction time sufficient to form a hydrogenated titanium alloy product, wherein the co-reduction is carried out by heating to the reduction temperature under an inert gas and then introducing a hydrogen atmosphere upon reaching approximately 10% recovery temperature; heat treating the composite hydrogenated titanium product under a hydrogen atmosphere and at a heat treatment temperature to reduce pore size and specific surface area to form a heat treated hydrogenated titanium product; and deoxygenating the heat treated hydrogenated titanium product to reduce residual oxygen to less than 0.3 wt.% to form deoxygenated hydrogenated titanium product. 29. The method of claim 28, wherein the at least one alloying element powder is at least one of a metal oxide powder, an elemental metal powder, and a metal hydride powder, and further wherein the metal oxide powder is selected from the group consisting of Al ₂ O ₃ , V ₂ O ₅ , CuO, MnO, V ₂ O ₃ , Fe ₂ O ₃ , Nb ₂ O ₅ , ZrO ₂ , MoO ₃ , MoO ₂ , Cr ₂ O ₃ , SnO ₂ , SiO ₂ , Ta ₂ O ₅ , CoO, WO ₃ , MO and combinations thereof, wherein the elemental metal is selected from the group consisting of Al, Mo, V, Nb, Ta, Fe, Cr, Mn, Co, Cu, W, Zr, Sn, Ni , Si and their combinations; and wherein the metal hydride is selected from the group consisting of aluminum hydride, vanadium hydride, niobium hydride, tantalum hydride, zirconium hydride, silicon hydride, and combinations thereof. 30. A method for producing a product in the form of a dispersed titanium alloy, including obtaining a mixture of composite dispersed oxides, including titanium oxide powder and at least one alloying element powder; joint reduction of a mixture of composite dispersed oxides using metallic