JP2992669B2 - Method for producing alumina-dispersed aluminum-titanium intermetallic compound composite containing specific impurities and titanium dioxide containing impurities - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to aluminum or aluminum.
Utilizes redox reaction between aluminum alloy and titanium dioxide
In order to obtain the used particle-reinforced high-hardness composite material,
Unreacted titanium dioxide with pure substance and aluminum (alloy)
Using the composite material as a precursor, the solid phase temperature of the matrix
Particles (α-alumina and aluminum)
Reaction product of the metal-titanium intermetallic compound)
Control the curing reaction (reaction product quantity ratio)
Alumina-dispersed aluminum containing specific impurities
Method for producing titanium-titanium intermetallic compound composite material and starting method
Regarding titanium dioxide containing impurities used as raw material
You.

[0002]

2. Description of the Related Art In general, composite materials include dispersion strengthening materials,
There are particle reinforced materials and fiber reinforced materials, each of which has its own characteristics. The purpose of composite materials using aluminum alloy as a matrix is to improve the strength characteristics (mechanical strength, high temperature strength, hardness, elastic modulus) of aluminum alloys. And to obtain a light-weight, high-hardness heat-resistant and wear-resistant material.

[0003] In recent years, in the development of such a composite material, a very high strength and high hardness ceramic fiber has been developed so that a high strength composite material can be obtained in a small amount by mixing a reinforcing material having the highest possible hardness. Although several composite materials using reinforcing materials such as ceramics, ceramic particles, and various whiskers have been proposed, there are still many unexplored fields.

[0004] Particularly in intermetallic compound composite materials,
One is to take titanium aluminide as the transition metal aluminide and try to satisfy the demands and expectations for an excellent and hard practical material and its strengthening method (hardening method).

[0005] For example, there is a hard material obtained by subjecting aluminum or an aluminum alloy and titanium dioxide (rutile) to composite / structural adjustment (heat treatment) and reaction-hardening the same as proposed by the present applicant (or the inventor). (Japanese Patent Application No. 3-86084
No.)

Up to now, an age hardening treatment following solution treatment has been well known as a method of strengthening or hardening an aluminum alloy. However, the Vickers hardness of general industrial aluminum alloys (practical alloys) by this method is as follows. There is a problem that this cannot be exceeded in the range of about 180 to 200, and recently various developments for obtaining a hard composite material by reacting a reinforcing material with an aluminum alloy have been carried out.

However, in most cases, the reaction occurs in the liquidus temperature range of the aluminum alloy.
There have been few attempts to combine titanium dioxide as a reinforcing material with an aluminum alloy as a matrix, and there have been no attempts to heat treat and harden a composite material of titanium dioxide containing impurities and aluminum or an aluminum alloy at a solidus temperature. is there.

This is because, as will be described later in the structure of the present invention, a composite is first produced under a temperature condition that does not cause a reaction between titanium dioxide and an aluminum alloy containing a specific element as an impurity. The alloy material is reacted by heat treatment in the solid phase temperature range of the aluminum alloy to control the progress of the hardening reaction to adjust the hardness. Further, when the volume fraction of titanium dioxide containing impurities becomes 31% or more, the entire composite material is This is because it can be changed to an alumina-dispersed aluminum-titanium intermetallic compound, and no aluminum alloy composite material having such a material design (or possible) has been found so far.

The present inventors have conducted a reaction analysis relating to a study on a composite composite material of titanium dioxide and an aluminum alloy, and found that a composite material of titanium dioxide (rutile) and aluminum containing no specific impurity element has a solidus temperature. In the composite material of titanium dioxide (rutile) and aluminum to which specific impurity elements sodium and potassium are added, a reaction occurs at a temperature lower than the melting point of aluminum, whereas the reaction of titanium dioxide and aluminum does not occur. The formation of the product α-alumina and the aluminum-titanium intermetallic compound was observed. [Totori, et al .: Abstracts of the Japan Institute of Metals (1993, 112th) p. 319]

After that, experiments and studies were repeated on various types of impurity elements added to titanium dioxide (rutile). As a result, among many elements, the reaction was carried out at a temperature lower than the melting point of aluminum in addition to the above sodium and potassium. It was possible to substantially identify impurity elements which were generated and in which α-alumina, which is a reaction product of titanium dioxide and aluminum, and formation of an aluminum-titanium intermetallic compound were recognized.

[0011] These specific elements are a group of elements having a larger ionic radius than the titanium ion (Ti ²⁺ ) in titanium dioxide.
All elements having an ionic radius larger than i ²⁺ ) are expected to be effective as additional elements (impurities).

[0012]

SUMMARY OF THE INVENTION The present invention has been made based on such findings and experimental facts, and is a particle-reinforced high-hardness composite material which has solved the above-mentioned problems centered on hardness. In the process of compounding titanium dioxide containing impurities and aluminum or aluminum alloy, first, an unreacted composite material is prepared, and the unreacted composite material is used as a precursor at a temperature in the solid phase range of the matrix to advance the curing reaction. By controlling (adjusting the amount ratio of reaction products) , alumina-dispersed aluminum containing specific impurities that can be material-designed in a wide range from aluminum alloy hardened materials to alumina-dispersed aluminum-titanium intermetallic compound composite materials
Method for producing titanium-titanium intermetallic compound composite material and starting method
It is an object of the present invention to provide an impurity-containing titanium dioxide used as a raw material .

[0013]

Means for Solving the Problems The present invention to achieve the above object, alumina dispersed aluminum containing specific impurities - A method of manufacturing a titanium intermetallic compound composite material, the titanium dioxide of the rutile crystal system One or more components whose ionic radius is larger than titanium ion (Ti ²⁺ ) in the oxide and whose weight ratio to titanium dioxide is 0.01% or more in terms of the oxide. A specific element of at least Group IA,
Vidium, Cesium, and Group IIA Calcium, Stra
An element selected from the group consisting of metal elements such as nium and barium is contained as an impurity, and the titanium dioxide containing the impurity is combined with aluminum or an aluminum alloy to form an unreacted composite material. It is characterized in that it is heat-treated at a local temperature to react and produce α-alumina and an aluminum-titanium intermetallic compound, and to control the curing reaction including the structure adjustment.

Here, aluminum or aluminum
Volume ratio of the impurity-containing titanium dioxide to
3% or more and 70% or less.

Further, aluminum or aluminum
Precursor utilizing redox reaction between alloy and titanium dioxide
Aluminum-dioxide containing certain impurities as
A non-reacted composite material is prepared and this is
Α-alumina and aluminum
Reaction and intercalation of the intermetallic compound
Can be obtained by controlling the curing reaction, including adjustment.
Alumina-dispersed aluminum containing specific impurities
-An impurity-containing titanium dioxide used as a starting material of a titanium intermetallic compound composite material , having the following properties. (A) The titanium dioxide has a rutile crystal system. (B) the impurity is one or more specific elements that contribute to the solid-phase reaction after unreacted complexation, has an ionic radius larger than titanium ion (Ti ²⁺ ) in the oxide, and The composition is adjusted so that the weight ratio with respect to the oxide is 0.01% or more in terms of oxide. (C) one or more specific elements as impurities are small;
At least sodium, rubidium, cesium,
Of group IIA calcium, strontium and barium
It is selected from the group of metal elements.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings (including a photograph of a structure). (Hereinafter, the substance names are indicated by chemical formulas in the description of the examples.)

[0017] powder TiO ₂ (rutile), for each K, Na, Ca, Ba, Sr, Cs, one or more oxides selected from Rb, wherein TiO ₂ and Na ₂ O is (rutile), Add a small amount of 0.3% by weight and mix well with a planetary ball mill. Then, it is cold-pressed and molded in an electric furnace at 800 to 1000 ° C.
Is applied to diffuse the impurity element into the TiO ₂ crystal grains. At the same time, the compact is in a pre-sintered state, and the strength of the compact is increased.

Next, this was used as a preform of composite material [Ti
The volume ratio of O ₂ (rutile) is about 40%], the mixture is heated together with the mold at 250 ° C. or lower, a predetermined amount of molten aluminum adjusted to 700 ° C. or lower is injected, and immediately pressurized to form a composite. The material subjected to the composite treatment under the composite conditions is composited with almost no reaction and exhibits a homogeneous microscopic structure as shown in the structure photograph of FIG.

Subsequently, a heat treatment is performed at 600 ° C. for 5 hours to cure by reaction. FIG. 2 shows a photograph of the microstructure. Under this material and heat treatment conditions, the matrix changes from the initial Al to the Al / Ti intermetallic compound (2) by the reaction, and a structure in which α-Al ₂ O ₃ (1) is uniformly dispersed can be obtained. As described above, a homogeneous tissue is shown in spite of a high magnification of 10,000 times. However, the size of this structure also depends on the size of TiO ₂ used.

Next, with respect to the unreacted composite material shown in FIG. 1 (photograph), the results of differential thermal analysis (DTA) in each case where the impurity element contained in titanium dioxide was changed are shown in FIGS. Show.

Here, the composite material indicated by each DTA curve is as follows:
FIG. 3 shows TiO ₂ (rutile)-containing almost no impurities.
Al composite material, FIG. 4 shows a TiO ₂ (rutile) -Al composite material containing 0.3% of Na as its oxide (Na ₂ O),
FIG. 5 shows T containing 0.3% of K as its oxide (K ₂ O).
iO ₂ (rutile) -Al composite material, the oxide 6 is Ca (CaO) as 0.3% containing TiO ₂ (rutile)
-Al composite material, FIG. 7 shows Rb as its oxide (Rb ₂ O)
8 (TiO ₂ (rutile) -Al composite material containing 0.3% as Sr, 0.3% of Sr as its oxide (SrO)
FIG. 9 shows TiO ₂ (rutile) -Al composite material containing 0.3% of Cs as its oxide (Cs ₂ O)
₂ (rutile) -Al composite material and FIG. 10 shows TiO ₂ (rutile) containing 0.3% of Ba as its oxide (BaO).
-Al composite material.

Focusing on the vicinity of the peak in each of the above figures (low temperature side where ΔT changes rapidly), FIG. 3 shows the case of TiO ₂ (rutile) to which impurities are not added.
Exothermic reaction at a temperature higher than the melting point of TiO ₂ (rutile) to which each impurity is added (FIGS. 4 to 10).
It can be seen that an exothermic reaction occurs even at a temperature lower than the melting point of Al.

FIG. 11 shows an example in which a TiO ₂ (rutile) -Al composite material to which Na among specific impurity elements is added reacts and cures by heat treatment. here,
Composite material of TiO ₂ (rutile) powder containing 0.2% by weight of Na in terms of its oxide (Na ₂ O) ratio and Al [TiO 2
₂ (rutile) is about 40% based on Al]
The graph shows the degree of curing [Vickers hardness: Hv (500)] with respect to time when heat treatment is performed in a temperature range of up to 600 ° C. In addition, the material was treated at 600 ° C. before
FIG. 12 shows the results of X-ray diffraction analysis of the composite material after the heat treatment for 0 second, 1 hour, and 42 hours.

In this material, a mild exothermic reaction is observed from around 600 ° C. before the melting point of Al (FIG. 4). For example, when heat treatment is performed at this temperature (600 ° C.), the Vickers hardness becomes Hv ≒ 220 before the treatment (when combined). Hv ≒ after heat treatment for 1 hour
Hv ≒ 720 after heat treatment at 450 and 24 hours and Hv ≒ 750 after heat treatment at 42 hours increase with heat treatment time (FIG. 11). The reaction product α-Al
₂ O ₃ and the Al / Ti intermetallic compound (mainly Al ₃ Ti) appear clearly and gradually increase in their amounts, and eventually they all turn into reaction products. That is,
As shown in FIG. 12, before the heat treatment, only diffraction peaks of Al and TiO ₂ are observed, but as the heat treatment time increases, the diffraction peaks of α-Al ₂ O ₃ and Al ₃ Ti increase. .

The reaction product at this time is high-purity TiO.
₂ (rutile) -Al composite material is the same as the reaction product that appears near the melting point, and therefore the effect of the impurities on the reaction is to shift the reaction initiation temperature to the solid phase temperature, that is, to the low temperature side. I can say.

Further, the oxide Na _(Na 2 O) ratio of a composite material of TiO ₂ containing 0.2 wt% (rutile) powder and Al casting alloy AC4C (JIS standard) [Ti
O ₂ to about 40% volume fraction of (rutile) Whereas AC4C material]
Is that the hardness at the time of compounding is Hv ス 240 in Vickers hardness, but when this is heat-treated at 540 ° C. for 1 hour, Hv ≒
400 and further heat-treated at 540 ° C. for 30 hours to be cured to about Hv ≒ 600.

In this case, AC4C is Si [6.5-7.
5%] and Mg [0.25 to 0.45%], a compound of these and Ti is generated, and the change in hardness with respect to the heat treatment time is slightly different from that in the case of FIG. 11 described above. come.

When the Al alloy contains alloy elements such as Si, Mg and Cu, α-Al ₂ O _{3 is} used as a reaction product.
Alloying elements and T / Al / Ti intermetallic compounds
Compounds containing i may be generated in plural.

As described above, in the present invention, a desired composite material can be obtained not only from pure Al but also from TiO ₂ (rutile) for Al alloy, and the range of material design is wide. That is,
A composite material that controls the progress of the reaction (reaction product amount) by the volume ratio of TiO ₂ (rutile) and the heat treatment conditions, and covers from aluminum alloy hardened material to alumina dispersed aluminum-titanium intermetallic compound composite material in material design. It can be said that.

[0030]

According to the present invention, there is provided the present invention comprising the steps of preparing impurity-containing titanium dioxide (rutile),
Unreacted composite material by compounding with minium (alloy)
Can be prepared, and this is used as a precursor to a matrix (Al
Minium alloy)
You. That is, α-alumina and aluminum
Reaction between the metal-titanium intermetallic compound and its texture
Can control the curing reaction (volume ratio of reaction products)
Easy material design, light weight, high hardness, heat resistance
Wear material is obtained. Moreover, unreacted composite material before curing
Has the advantage that it can be machined.

By controlling the curing reaction in this way,
For this type of material, various hardening materials, from unhardened composite materials, including unreacted composite materials, to alumina-dispersed aluminum-titanium intermetallic compound composite materials are included.
Since it can provide a high quality composite material , it has extremely high industrial value.

[Brief description of the drawings]

FIG. 1 shows TiO ₂ (rutile)-containing 0.3% of Na as its oxide (Na ₂ O) in one embodiment of the present invention.
It is an electron micrograph of an Al composite material structure.

FIG. 2 is an electron micrograph of the same material cured by heat treatment.

FIG. 3 TiO ₂ (rutile) containing almost no impurities
It is explanatory drawing which shows the DTA curve of -Al composite material.

FIG. 4: 0.3% of Na as its oxide (Na ₂ O)
It is an explanatory view showing a DTA curve of TiO ₂ (rutile) -Al composite material comprising.

FIG. 5 is an explanatory diagram showing a DTA curve of a TiO ₂ (rutile) -Al composite material containing 0.3% of K as its oxide (K ₂ O).

FIG. 6 is an explanatory diagram showing a DTA curve of a TiO ₂ (rutile) -Al composite material containing 0.3% of Ca as its oxide (CaO).

FIG. 7: 0.3% of Rb as its oxide (Rb ₂ O)
It is an explanatory view showing a DTA curve of TiO ₂ (rutile) -Al composite material comprising.

FIG. 8 is an explanatory diagram showing a DTA curve of a TiO ₂ (rutile) -Al composite material containing 0.3% of Sr as its oxide (SrO).

FIG. 9 shows Cs as an oxide (Cs ₂ O) of 0.3%
It is an explanatory view showing a DTA curve of TiO ₂ (rutile) -Al composite material comprising.

FIG. 10: 0.3% of Ba as its oxide (BaO)
It is an explanatory view showing a DTA curve of TiO ₂ (rutile) -Al composite material comprising.

FIG. 11 is a graph showing Na as an oxide (Na ₂ O) of 0.2
FIG. 4 is an explanatory diagram showing a curing curve with respect to a heat treatment time when a TiO ₂ (rutile) -Al composite material containing 0.1% is heat-treated.

FIG. 12 is an explanatory diagram showing an analysis result by X-ray diffraction of a composite material at each heat treatment time when the material is heat-treated at 600 ° C.

[Explanation of symbols]

1 α-Al ₂ O ₃ (particles) 2 Al / Ti intermetallic compound (matrix)

Claims (3)

(57) [Claims] 1. In order to obtain a particle-reinforced high-hardness composite material utilizing an oxidation-reduction reaction between aluminum or an aluminum alloy and titanium dioxide, a rutile crystal titanium dioxide and a titanium ion (Ti) ²⁺ ) having a larger ionic radius and having a weight ratio to titanium dioxide of 0.01
% Or more of one or more specific elements whose composition is adjusted to be at least
, Cesium, and calcium of group IIA, strontium
An unreacted composite material is prepared by mixing an impurity selected from the group consisting of metal elements barium and barium as an impurity, and combining the titanium dioxide containing the impurity with aluminum or an aluminum alloy. Alumina-dispersed aluminum-titanium metal containing specific impurities, characterized in that it is heat-treated at a local temperature to form a reaction between α-alumina and an aluminum-titanium intermetallic compound, and controls a hardening reaction including adjustment of its structure. A method for producing a compound composite material. 2. The production of an alumina-dispersed aluminum-titanium intermetallic compound composite material containing a specific impurity according to claim 1, wherein the volume ratio of said impurity-containing titanium dioxide to aluminum or aluminum alloy is 3% or more and 70% or less. Method. 3. An aluminum-titanium dioxide unreacted composite material containing a specific impurity is prepared as a precursor utilizing a redox reaction between aluminum or an aluminum alloy and titanium dioxide, and the composite material is heated at the solidus temperature of the matrix. Alumina-dispersed aluminum-titanium intermetallic compound composite containing specific impurities that can be obtained by heat-treating to produce α-alumina and aluminum-titanium intermetallic compound and controlling the hardening reaction including its structure adjustment An impurity-containing titanium dioxide, which is a starting material of a material and has the following properties. (A) The titanium dioxide has a rutile crystal system. (B) the impurity is one or more specific elements that contribute to the solid-phase reaction after unreacted complexation, has an ionic radius larger than titanium ion (Ti ²⁺ ) in the oxide, and The composition is adjusted so that the weight ratio with respect to the oxide is 0.01% or more in terms of oxide. (C) one or more specific elements as impurities are small;
At least sodium, rubidium, cesium,
Of group IIA calcium, strontium and barium
It is selected from the group of metal elements.