CN111575522A

CN111575522A - Additives for improving castability of aluminum-boron carbide composites

Info

Publication number: CN111575522A
Application number: CN202010441074.4A
Authority: CN
Inventors: 约瑟夫·朗格莱; 内威·安德拉德; 让-阿兰·劳林
Original assignee: Rio Tinto Alcan International Ltd
Current assignee: Rio Tinto Alcan International Ltd
Priority date: 2012-11-19
Filing date: 2013-11-19
Publication date: 2020-08-25
Also published as: CN104755194A; US20200002792A1; EP2919932B1; WO2014075194A1; AU2013344742A8; JP2016502604A; AU2013344742C1; CA2890771A1; KR102014330B1; EP2919932A4; EP2919932A1; AU2013344742A1; JP6245267B2; KR20150101443A; AU2013344742B2; US20150275338A1

Abstract

The present invention relates to additives for improving the castability of aluminum-boron carbide composites. The present disclosure provides additives capable of undergoing a peritectic reaction with boron in an aluminum-boron carbide composite. The additives may be selected from the group consisting of vanadium, zirconium, niobium, strontium, chromium, molybdenum, hafnium, scandium, tantalum, tungsten, and combinations thereof, for maintaining the fluidity of the molten composite material prior to casting to promote castability.

Description

Additives for improving castability of aluminum-boron carbide composites

The present application is a divisional application of chinese patent application No.201380055557.9 entitled "additive for improving castability of aluminum-boron carbide composite material" filed on 2013, 11 and 19.

Cross Reference to Related Applications

This application claims priority from U.S. provisional patent application 61/727,949 filed on day 11, 19, 2012 and incorporated herein in its entirety.

Technical Field

The present invention relates to cast aluminum/boron carbide composite metal matrix materials having a product obtained from a peritectic reaction to increase the fluidity thereof prior to casting. The reaction product is obtained by using an additive capable of undergoing a peritectic reaction with boron of the boron carbide.

Background

To increase the melting of Al-B₄C fluidity of the mixture, and titanium may be added as described in U.S. patent No. 7,562,962. When adding titanium to molten aluminum metal and B₄In the mixture of C powders, in B₄C particles and B₄Reaction products are formed near the interface of the aluminum matrix where the C particles are "poisoned". It is taught that the reaction product is B₄The C particles are shielded from the aluminum.

It would be highly desirable to provide for maintaining molten Al-B prior to casting and forming₄Means and methods for proper fluidity of the C mixture. These means and methods will preferably provide/maintain flowability that can withstand forming and/or casting in an industrial environment.

Disclosure of Invention

Summary of The Invention

The present disclosure provides a cast composite material comprising aluminum, a product of a peritectic reaction between an additive and boron, and dispersed boron carbide particles. The presence of the products of the peritectic reaction maintains the fluidity of the molten composite prior to casting and promotes the castability and shaping of the composite.

In a first aspect, the present disclosure provides a cast composite material comprising (i) aluminum, (ii) a product of a peritectic reaction between an additive and boron, (iii) dispersed boron carbide particles, and (iv) optionally titanium. The additive is selected from the group consisting of chromium, molybdenum, vanadium, niobium, zirconium, strontium, scandium, and any combination thereof. A sample of the composite material had fluidity after having been heated to a temperature of about 700 ℃ for about 120 minutes prior to casting, corresponding to a cast length of at least 100mm when measured using a mold having a groove for receiving the sample, such groove having a width of about 33mm, a height of between about 6.5mm and about 4.0mm, and being inclined downwardly from a horizontal axis by about 10 °. In one embodiment, the cast length of the sample is at least 190 mm. In another embodiment, the cast composite material is held for a holding time and cast for a casting time, and wherein the holding time and the casting time total 120 minutes. In another embodiment, the product of the peritectic reaction is provided by combining molten aluminum or molten aluminum alloy with an additive capable of undergoing a peritectic reaction (prior to incorporation of the boron carbide particles). In another embodiment, the additive is selected from the group consisting of zirconium, strontium, scandium, and any combination thereof. In another embodiment, the additive is scandium. In another embodiment, the additive is strontium. In another embodiment, the additive is zirconium. In one embodiment, the concentration (v/v) of the dispersed boron carbide particles is between 4% and 40% based on the total volume of the cast composite material. In such embodiments, the concentration (w/w) of the additive may be between 0.47% and 8.00% by total weight of the cast composite material, and optionally, the composite material may further comprise titanium at a concentration (w/w) between 0.50% and 4.00% by total weight of the cast composite material. In another embodiment, the concentration (v/v) of the dispersed boron carbide particles is between 4.5% and 18.9% based on the total volume of the cast composite material. In such embodiments, the concentration (w/w) of the additive may be between 0.38% and 4.00% by total weight of the cast composite material, and optionally, the cast composite material further comprises titanium at a concentration (w/w) between 0.40% and 2.00% by total weight of the cast composite material. In another embodiment, the concentration (v/v) of the dispersed boron carbide particles is between 19.0% and 28.0% based on the total volume of the cast composite material. In such embodiments, the concentration (w/w) of the additive may be between 1.68% and 6.00% by total weight of the cast composite material, and optionally, the cast composite material may further comprise titanium at a concentration (w/w) between 1.80% and 3.00% by total weight of the cast composite material. In another embodiment, the concentration (v/v) of the dispersed boron carbide particles is between 25.0% and 28.0% or between 28.0% and 33.0% by total volume of the cast composite material. In such embodiments, the concentration (w/w) of the additive may be between 0.94% and 4.00% based on the total weight of the cast composite material, and optionally, the cast composite material may further comprise titanium at a concentration (w/w) between 1.00% and 2.00% based on the total weight of the cast composite material.

According to a second aspect, the present disclosure provides a method of making a cast composite material. Broadly, such a method comprises (a) combining (i) a molten aluminum alloy comprising an additive capable of undergoing a peritectic reaction with boron and (ii) a source of boron carbide particles to provide a molten composite comprising a product of the peritectic reaction between the additive and boron and dispersed boron carbide particles; and (b) casting the molten composite to form a cast composite material. The additive is selected from the group consisting of chromium, molybdenum, vanadium, niobium, zirconium, strontium, scandium, and any combination thereof. A sample of the composite material had fluidity after having been heated to a temperature of about 700 ℃ for about 120 minutes prior to casting, corresponding to a cast length of at least 100mm when measured using a mold having a groove for receiving the sample, such groove having a width of about 33mm, a height of between about 6.5mm and about 4.0mm, and being inclined downwardly from a horizontal axis by about 10 °. In one embodiment, the cast length is at least 190 mm. In another embodiment, the method further comprises holding the molten composite material for a holding time and casting the molten composite for a casting time prior to step (b), wherein the holding time and the casting time total 120 minutes. In another embodiment, the method further comprises, prior to step (a), providing the molten aluminum alloy by combining the molten aluminum or molten aluminum alloy with an additive capable of undergoing a peritectic reaction. Embodiments have been described above and applied herein with respect to the type of additives that may be used, the concentration of the additives, the concentration of the boron carbide particles, the optional presence of titanium in the composite material.

According to a third aspect, the present disclosure provides a method of improving the casting and/or shaping characteristics of a molten composite material comprising aluminum, a product of a peritectic reaction between an additive and boron, and dispersed boron carbide particles. Broadly, this method comprises combining (i) a molten aluminum alloy comprising an additive capable of undergoing a peritectic reaction with boron and (ii) a source of boron carbide particles to provide a molten composite material. The additive is selected from the group consisting of chromium, molybdenum, vanadium, niobium, zirconium, strontium, scandium, and any combination thereof. A sample of the composite material had fluidity after having been heated to a temperature of about 700 ℃ for about 120 minutes prior to casting, corresponding to a cast length of at least 100mm when measured using a mold having a groove for receiving the sample, such groove having a width of about 33mm, a height of between about 6.5mm and about 4.0mm, and being inclined downwardly from a horizontal axis by about 10 °. Embodiments have been described above and applied herein with respect to casting length, type of additives that may be used, concentration of additives, concentration of boron carbide particles, optional presence of titanium in the composite material.

According to a fourth aspect, the present disclosure provides a method of promoting the formation of a molten composite material comprising aluminum, the product of a peritectic reaction between an additive and boron, and dispersed boron carbide particles. Broadly, this method comprises combining (i) a molten aluminum alloy comprising an additive capable of undergoing a peritectic reaction with boron and (ii) a source of boron carbide particles to provide a molten composite material. The additive is selected from the group consisting of chromium, molybdenum, vanadium, niobium, zirconium, strontium, scandium, and any combination thereof. A sample of the composite material had fluidity after having been heated to a temperature of about 700 ℃ for about 120 minutes prior to casting, corresponding to a cast length of at least 100mm when measured using a mold having a groove for receiving the sample, such groove having a width of about 33mm, a height of between about 6.5mm and about 4.0mm, and being inclined downwardly from a horizontal axis by about 10 °. Embodiments have been described above and applied herein with respect to casting length, type of additives that may be used, concentration of additives, concentration of boron carbide particles, optional presence of titanium in the composite material.

Drawings

Having thus described the nature of the invention in general terms, reference will now be made to the accompanying drawings, in which:

FIG. 1 shows B with different batches₄Loss of fluidity of the molten aluminum mixture of C powder. Results for multiple batches (a to E) of B added to molten aluminium at an initial temperature of 735 ℃₄The C powder (30% v/v) is shown with flowability as a function of hold time in the furnace (min) (measured in cast length (mm) of the sample measured using a K-die.) the results are shown for batch A (◆) containing 3.5% w/wTi, batch B (■) containing 3.5% w/w Ti, batch C (▲) containing 3.5% w/w Ti, batch D (●) containing 3.0% w/w Ti, and batch E (○) containing 2.0% w/w Ti.

Fig. 2A-2C illustrate one embodiment of a K-die that may be used to determine the cast length of a composite material. (2A) A schematic side elevation view of the lower inclined portion 10 of the K-die. (2B) A schematic top elevation view of the grooved portion 40 of the K-die. (2C) A schematic cross-sectional view of the groove-containing portion 50 of the K-die.

Detailed Description

Having a high B₄The manufacture of boron Metal Matrix Composites (MMCs) having C content (e.g., at least 30% v/v) typically requires B of exceptional quality₄And C, powder. High quality of B₄The C powder has a good particle size distribution and has a minimum of fine powder-like particles. In general, only such B₄The C powder may be incorporated in large amounts into the metal matrix. When B is present₄Without said good quality of the C powder, a significant loss of fluidity can be observed during the holding time of the molten metal, i.e. before casting. In addition, increasing the holding temperature of the molten metal does not compensate for this loss of fluidity, as this may favor aluminum and B₄C powder, thereby further increasing the viscosity (loss of fluidity). In such a case, the molten metal behaves as a thixotropic material.

Figure 1 shows the loss of fluidity over the holding time of the molten compound prior to casting. In an industrial environment, for oneA certain fluidity is required for a certain amount of time to allow Al-B₄C forming/casting of the mixture. The curve shown in FIG. 1 shows B for the preparation of the composite₄C powder increases the viscosity of the material and fails to meet the fluidity required for the subsequent steps (e.g. forming) in an industrial environment, even in the presence of titanium.

In accordance with the present disclosure, a cast Al-B is provided₄A C composite material comprising aluminum, a product of a peritectic reaction, and dispersed boron carbide particles. The composite material is obtained by first combining aluminium (or an aluminium alloy) with an additive (or a combination of additives) capable of undergoing a peritectic reaction with boron of the boron carbide particles and finally providing the product of said peritectic reaction in the aluminium or aluminium alloy. After the additive has been included in the aluminum (or aluminum alloy), boron carbide particles are combined with the aluminum (or aluminum alloy) such that a peritectic reaction occurs between the additive and the boron. As shown herein, the use of additives in aluminum/aluminum alloys (and ultimately the presence of peritectic reaction products in the composite) has been shown to be useful in maintaining the fluidity of the molten composite and as such, imparting good castability to the molten composite. In some embodiments, it is believed that the use of additives inhibits or slows down reaction products (e.g., between Al and B) produced during the holding of the molten composite₄Between C or Al and B₄Reaction products generated between C). In other embodiments, it has been shown that additives may be used to limit the use of titanium in the composite without substantially altering its flowability. This maintenance of the fluidity of the molten composite material may allow for extended holding times of the molten mixture in the furnace in order to use lower grades of B₄C source and to facilitate shaping and/or casting of the resulting metal matrix composite.

Prior to casting, the composite material is in a molten state and has fluidity. In the disclosure described herein, the molten composite material has a fluidity prior to casting that allows for casting in an industrial environment. To determine the flowability of the molten composite, it is possible to use a K-die. The molds currently used and known in the art measure the length of a sample of the composite material prior to curing. The length measured with the K-die is called the casting length.

One embodiment of a K-die that can be used to determine the flowability of a sample of molten composite material is shown in fig. 2A-2C. The K-die is generally composed of two engageable portions, a lower inclined portion 010 (as shown in fig. 2A) and a groove-containing portion 040 (as shown in fig. 2B and 2C). When the sample is inserted into the mold, the inclined portion 010 engages with the groove-containing portion 040. The sample is cast along the inclined portion 010 and within the groove 040 until it solidifies. The length covered by a sample, usually measured in millimeters, is a measure of fluidity and refers to the cast length.

As shown in fig. 2A, the lower inclined portion is generally monolithic and comprises a flat 015 having a smooth surface and inclined downwardly from a horizontal axis 020 by an angle 030 of about 10 °. The flat plane 015 is for directly contacting the exterior side 055 of the grooved portion 040 (shown in fig. 2B and 2C) and for providing the groove with an angle of about 10 °.

Groove-containing portion 040 is a partially hollow structure that defines closable groove 050 (fig. 2B) for holding a sample of molten compound. As shown in fig. 2B, the groove-containing portion has an outer side 055 for directly contacting the flat plane 015 of the inclined portion 010. In the embodiment shown in fig. 2B, groove 050 contains two distinct segments: section 060 and section 070 (defining the projection). In some embodiments, the K-die comprises at least four sections 070 (e.g., four protrusions) located at distances of 93mm, 130mm, 168mm, and 205mm from the beginning of the die (e.g., where the sample begins to contact the inclined plane 015).

Figure 2C shows an enlarged view of the closable recess 050. Segment 060 has a similar height 061 of about 6.5 mm. The height 061 is a constant between the lengths defined by the outer walls 055. The height 061 is measured about an axis 080 defined by the inclined plane 015 (when the groove-containing portion 040 is engaged with the inclined portion 010). Section 070 also has a similar height 071 of about 4 mm. The height 071 is constant between the lengths defined by the outer walls 055. This height is measured with respect to the axis 080 defined by the inclined plane 015 (when the groove-containing portion 040 is engaged on the inclined portion 010).

In the context of the present disclosure, the cast composite material preferably has a fluidity prior to casting, corresponding to a cast sample length of at least 100mm, at least 120mm, at least 140mm, at least 160mm, at least 180mm, at least 190mm or at least 200 mm. The sample used to determine the fluidity of the composite material can be heated at a temperature of about 700 c for about 120 minutes to reproduce an industrial casting environment.

Accordingly, the present disclosure also provides a method of making a cast composite material. To do so, a molten aluminum alloy (also referred to as an aluminum-based matrix alloy) containing an additive (or combination of additives) capable of undergoing a peritectic reaction is combined with a source of boron carbide to provide a molten composite. As shown in the present disclosure, the fluidity of the molten compound can be maintained at acceptable industrial levels for a longer period of time than a similar molten compound lacking the additive.

In the methods described herein, the aluminum or aluminum alloy used is provided in molten form. In this case, aluminum or aluminum alloys are used in combination with B₄The C particles are preferably heated to their melting temperature prior to combination. In one embodiment, the aluminum alloy comprises (in embodiments consists essentially of, and in other embodiments consists of) an additive capable of undergoing a peritectic reaction, the remainder being essentially aluminum or an aluminum alloy. Impurities which are unavoidable or inevitably present (up to 0.05% w/w of each impurity) may also be present in the alloy (up to 0.15% w/w of the impurities in total). Exemplary aluminum alloys include, but are not limited to, alloys from the 11xx series and from the 6xxx series. In some embodiments, Ti may be included in the aluminum or aluminum alloy. In an alternative embodiment, if Ti is present in the aluminum or molten aluminum alloy, it is considered a trace element (e.g., its concentration does not exceed the concentration of impurities that must be present).

In one embodiment, the composite material comprises between 4% and 40% (v/v) of B₄C particles, and the molar concentration of the additive (or combination of additives) in the composite material is between 0.01044 and 0.08351. In some embodiments, when Ti is present in the composite material, the additive (or combination of additives) is present in a combined molar concentration with the TiBetween 0.01044 and 0.08351. In some embodiments, the concentration of the additive in the composite is in the form of a composite (comprising B)₄C particles) may be between 0.47% to 15.32%, 0.47% to 8.00%, 0.90% to 8.00%, 0.95% to 8.00%, 1.00% to 8.00%, or 1.10% to 8.00% by total weight. In some embodiments, the combined concentration of the additive and Ti in the composite is in the form of a composite material (comprising B)₄C particles) may be between 0.47% to 15.32%, 0.47% to 8.00%, 0.90% to 8.00%, 0.95% to 8.00%, 1.00% to 8.00%, or 1.10% to 8.00% by total weight.

In another embodiment, the composite material comprises between 4.5% and 18.9% (v/v) B₄C particles, and the molar concentration of the additive (or combination of additives) in the composite material is between 0.00835 and 0.04175. In some embodiments, when Ti is present in the composite material, the combined molar concentration of the additive (or combination of additives) and Ti is between 0.00835 and 0.04175. In some embodiments, the concentration of the additive in the composite is in the form of a composite (comprising B)₄C particles) may be between 0.38% to 7.68%, 0.38% to 4.00%, 0.90% to 4.00%, 0.95% to 4.00%, 1.00% to 4.00%, or 1.10% to 4.00% by total weight. In some embodiments, the combined concentration of the additive and Ti in the composite is in the form of a composite material (comprising B)₄C particles) may be between 0.38% to 7.68%, 0.38% to 4.00%, 0.90% to 4.00%, 1.00% to 4.00%, or 1.10% to 4.00% by total weight.

In another embodiment, the composite material comprises between 19% and 28% (v/v) of B₄C particles, and the molar concentration of the additive (or combination of additives) in the composite material is between 0.03758 and 0.06263. In some embodiments, when Ti is present in the composite material, the combined molar concentration of the additive (or combination of additives) and Ti is between 0.03758 and 0.06263. In some embodiments, the concentration of the additive in the composite is in the form of a composite (comprising B)₄C particles) may be between 1.69% to 11.51% or 1.69% to 6.00% by total weight. In some casesIn embodiments, the combined concentration of the additive and Ti in the composite is in the form of a composite material (comprising B)₄C particles) may be between 1.69% to 11.51% or 1.69% to 6.00% by total weight.

In another embodiment, the composite material comprises between 25% and 28% (v/v) or between 28% and 33% (v/v) of B₄C particles, and the molar concentration of the additive (or combination of additives) in the composite material is between 0.02088 and 0.04175. In some embodiments, when Ti is present in the composite material, the combined molar concentration of the additive (or combination of additives) and Ti is between 0.02088 and 0.04175. In some embodiments, the concentration of the additive in the composite is in the form of a composite (comprising B)₄C particles) may be between 0.94% to 7.68%, 0.94% to 4.00%, 0.95% to 4.00%, 1.00% to 4.00%, or 1.10% to 4.00% by total weight. In some embodiments, the combined concentration of the additive and Ti in the composite is in the form of a composite material (comprising B)₄C particles) may be between 0.94% to 7.68%, 0.94% to 4.00%, 0.95% to 4.00%, 1.00% to 4.00%, or 1.10% to 4.00% by total weight.

The concentration of the additive, whether provided in a weight percent concentration or in a certain molar concentration, whether with reference to the aluminum alloy or the total composite material, is understood to include all forms of the additive (including soluble additives, excess additives coming out of solution in the form of intermetallic or refractory compounds, and additives included in the B-containing peritectic reaction product). The additive capable of promoting the formation of the product of the peritectic reaction may be added in any suitable form, including master alloys (e.g., Al-10% additive master alloys) or additive-containing granules or powders. In some embodiments, it is contemplated to add additives in powder form to wrought alloys (including AA1xxx, AA2xxx, AA3xxx, AA4xxx, or AA6xxx) or cast alloys (including AA2xx or AA3 xx).

Similarly, the titanium concentrations or molar concentrations given in the foregoing description, whether with reference to an aluminum alloy or a total composite, represent all forms of titanium (including soluble Ti, excess Ti coming out of solution as intermetallic or refractory compounds, and Ti-B compounds). The titanium may be added in any suitable form, including master alloys (e.g., Al-10% Ti master alloys) or titanium-containing particles or powders. In some embodiments, it may be advisable to use AA1xxx alloys containing titanium in the aluminum alloy. In alternative or complementary embodiments, it is contemplated to add titanium in the form of an aluminum alloy, such as a wrought alloy (including AA2xxx, AA3xxx, AA4xxx, or AA6xxx) or a cast alloy (including AA2xx or AA3 xx).

In some embodiments, the additive capable of promoting the formation of the product of the peritectic reaction may be zirconium, and the aluminum alloy may include or contain zirconium. In some embodiments, when Zr is used as an additive, the composite material does not include Ti (if present, Ti is considered a trace element). In other embodiments, when Zr is used as an additive, Ti may be present in the composite material. Between 4% and 40% (v/v) of B₄C particles of a composite material in which zirconium is present as a composite material (comprising B)₄C particles) may be provided at a concentration of between about 0.95 to about 7.61 wt.%, between about 1.00 to about 7.61 wt.%, or between about 1.10 to about 7.61 wt.%. In the embodiment, when Ti is present, it is in a composite material (comprising B)₄C particles) may be provided at a concentration of between about 0.50 to about 4.00 weight percent, between about 0.90 to about 4.00 weight percent, between about 0.95 to about 4.00 weight percent, between about 1.00 to about 4.00 weight percent, or between about 1.10 to about 4.00 weight percent. Between 4.5% and 18.9% (v/v) of B₄C particles of a composite material in which zirconium is present as a composite material (comprising B)₄C particles) may be provided at a concentration of between about 0.76 to about 3.81 weight percent, between about 0.90 to about 3.81 weight percent, between about 0.95 to about 3.81 weight percent, between about 1.00 to about 3.81 weight percent, or between about 1.10 to about 3.81 weight percent. In the embodiment, when Ti is present, it is in a composite material (comprising B)₄C particles) may be present in an amount of between about 0.40 to about 2.00 weight percent, between about 0.90 to about 2.00 weight percent, between about 0.95 to about 2.00 weight percent based on the total weight of the compositionConcentrations of between amount%, between about 1.00 to about 2.00 wt%, or between about 1.10 to about 2.00 wt% are provided. Between 19% and 28% (v/v) of B₄C particles of a composite material in which zirconium is present as a composite material (comprising B)₄C particles) may be provided at a concentration of between about 3.43 to about 5.71 weight percent based on the total weight of the composition. In the embodiment, when Ti is present, it is in a composite material (comprising B)₄C particles) may be provided at a concentration of between about 1.80 to about 3.00 weight percent based on the total weight of the particles. Between 25% and 28% (v/v) or 28% and 33% of B₄C particles of a composite material in which zirconium is present as a composite material (comprising B)₄C particles) may be provided at a concentration of between about 1.90 to about 3.81 weight percent based on the total weight of the composition. In the embodiment, when Ti is present, it is in a composite material (comprising B)₄C particles) may be provided at a concentration of between about 1.00 to about 2.00 weight percent or between about 1.10 to about 2.00 weight percent based on the total weight of the particles. It should be understood that the zirconium concentrations given in the foregoing description, whether with reference to an aluminum alloy or the total composite, represent all forms of zirconium (including soluble Zr, excess Zr coming out of solution as intermetallic or refractory compounds, and Zr — B compounds). The zirconium may be added in any suitable form, including master alloys (e.g., Al-10% Zr master alloys) or zirconium-containing particles or powders. In some embodiments, it may be advisable to use AA1xxx alloys containing zirconium in the aluminum alloy. In alternative or supplementary embodiments, it is contemplated to add zirconium in the form of an aluminum alloy, such as a wrought alloy (including AA2xxx, AA3xxx, AA4xxx or AA6xxx) or a cast alloy (including AA2xx or AA3 xx).

In some embodiments, the additive capable of promoting the formation of the product of the peritectic reaction may be strontium, and the aluminum alloy may include or contain strontium in combination with titanium. Between 4% and 40% (v/v) of B₄C particles of composite material, strontium in the form of composite material (containing B)₄C particles) may be present in an amount of between about 0.91 to about 7.32 weight percent, between about 0.95 to about 7.32 weight percent, between about 1.00 to about 7.32 weight percent, or between about 1.10 to about 7.32 weight percent based on the total weight of the composition% and titanium is provided in a composite material (comprising B)₄C particles) may be provided at a concentration of between about 0.50 to about 4.00 weight percent, between about 0.90 to about 4.00 weight percent, between about 0.95 to about 4.00 weight percent, between about 1.00 to about 4.00 weight percent, or between about 1.10 to about 4.00 weight percent. Between 4.5% and 18.9% (v/v) of B₄C particles of composite material, strontium in the form of composite material (containing B)₄C particles) may be provided at a concentration of between about 0.73 to about 3.66 wt.%, between about 0.90 to about 3.66 wt.%, between about 0.95 to about 3.66 wt.%, between about 1.00 to about 3.66 wt.%, or between about 1.10 to about 3.66 wt.%, based on the total weight of the composite material (including B particles), while titanium is provided as a composite material (including B particles)₄C particles) may be provided at a concentration of between about 0.40 to about 2.00 weight percent, between about 0.90 to about 2.00 weight percent, between about 0.95 to about 2.00 weight percent, between about 1.00 to about 2.00 weight percent, or between about 1.10 to about 2.00 weight percent. Between 19% and 28% (v/v) of B₄C particles of composite material, strontium in the form of composite material (containing B)₄C particles) may be provided at a concentration of between about 3.29 to about 5.49 weight percent based on the total weight of the composite material, with titanium being present as the composite material (comprising B)₄C particles) may be provided at a concentration of between about 1.80 to about 3.00 weight percent based on the total weight of the particles. Between 25% and 28% (v/v) or between 28% and 33% of B₄C particles of composite material, strontium in the form of composite material (containing B)₄C particles) may be provided at a concentration of between about 1.83 to about 3.66 weight percent, based on the total weight of the composite material, with titanium being present as the composite material (comprising B)₄C particles) may be provided at a concentration of between about 1.00 to about 2.00 weight percent or between about 1.10 to about 2.00 weight percent based on the total weight of the particles. It will be appreciated that the strontium concentrations given in the foregoing description, whether with reference to an aluminium alloy or the total composite, represent all forms of strontium (including soluble Sr, excess Sr coming out of solution as intermetallic or refractory compounds, and Sr-B compounds). The strontium can be added in any suitable form, including master alloys (e.g.,al-10% Sr master alloy) or strontium containing particles or powders. In some embodiments, it may be advisable to use AA1xxx alloys containing strontium in the aluminum alloy. In alternative or complementary embodiments, it is contemplated to add strontium in the form of an aluminum alloy, such as a wrought alloy (including AA2xxx, AA3xxx, AA4xxx, or AA6xxx) or a cast alloy (including AA2xx or AA3 xx).

In some embodiments, the additive capable of promoting the formation of the product of the peritectic reaction may be scandium, and the aluminum alloy may include or contain scandium in combination with titanium. Between 4% and 40% (v/v) of B₄C particles of scandium as a composite material (containing B)₄C particles) may be provided at a concentration of between about 0.47 to about 3.75 wt.%, between about 0.90 to about 3.75 wt.%, between about 1.00 to about 3.75 wt.%, or between about 1.10 to about 3.75 wt.%, based on the total weight of the composite material (including B particles), while titanium is provided as a composite material (including B particles)₄C particles) may be provided in a concentration of between about 0.50 to about 4.00, between about 0.90 to about 4.00, between about 0.95 to about 4.00, between about 1.00 to about 4.00, or between about 1.10 to about 4.00. Between 4.5% and 18.9% (v/v) of B₄C particles of scandium as a composite material (containing B)₄C particles) may be provided at a concentration of between about 0.38 to about 1.88 weight percent, between about 0.90 to about 1.88 weight percent, between about 1.00 to about 1.88 weight percent, or between about 1.10 to about 1.88 weight percent, based on the total weight of the composite material (including B particles), while titanium is provided as a composite material (including B particles)₄C particles) may be provided at a concentration of between about 0.40 to about 2.00 weight percent, between about 0.90 to about 2.00 weight percent, between about 0.95 to about 2.00 weight percent, between about 1.00 to about 2.00 weight percent, or between about 1.10 to about 2.00 weight percent. Between 19% and 28% (v/v) of B₄C particles of scandium as a composite material (containing B)₄C particles) may be provided at a concentration of between about 1.69 to about 2.82 weight percent, based on the total weight of the composite material, with titanium being present as the composite material (comprising B)₄C particles) may be provided at a concentration of between about 1.80 to about 3.00 weight percent based on the total weight of the particles.Between 25% and 28% (v/v) or 28% and 33% of B₄C particles of scandium as a composite material (containing B)₄C particles) may be provided at a concentration of between about 0.94 to about 1.88 wt.%, between about 1.00 to about 1.88 wt.%, or between about 1.10 to about 3.88 wt.%, based on the total weight of the composite material, while the titanium is provided as a composite material (comprising B particles)₄C particles) may be provided at a concentration of between about 1.00 to about 2.00 weight percent or between about 1.10 to about 2.00 weight percent based on the total weight of the particles. It will be appreciated that the scandium concentrations given in the foregoing description, whether with reference to an aluminium alloy or a total composite, represent all forms of scandium (including soluble Sc, excess Sc coming out of solution as intermetallic or refractory compounds, and Sc-B compounds). Scandium may be added in any suitable form, including master alloys (e.g., Al-10% Sc master alloys) or scandium-containing particles or powders. In some embodiments, it may be advisable to use AA1xxx alloys containing scandium in the aluminum alloy. In an alternative or supplementary embodiment, it is contemplated to add scandium in the form of an aluminium alloy, such as a wrought alloy (including AA2xxx, AA3xxx, AA4xxx or AA6xxx) or a cast alloy (including AA2xx or AA3 xx).

Without wishing to be bound by theory, additives may be used in the methods described herein to compare with AlB₂B, which has a more negative relative enthalpy of formation, forms a reaction product. For example, when vanadium is used in an aluminum alloy comprising titanium, it is believed, without wishing to be bound by theory, that this addition will force another reaction with the titanium to occur. The reaction product may be, for example, (Ti, V) B₂The compound of (1). The formation of the reaction product will stop or reduce the formation of titanium-containing aluminum melt and B₄C reaction between particles. The present disclosure thus provides for the addition of additives capable of promoting the formation of peritectic reaction products as aluminum melt and B₄C, the reaction between the particles, to maintain the fluidity of the compound until the compound is shaped, preferably cast.

Theoretical calculation of the enthalpy of formation of the reaction product expected to form after addition of various elements is the use of the software FactStage^TMWas performed and is shown in table 1.

TABLE 1 theoretical values of the enthalpy of formation of the various reaction products.

Added elements	And B₄Peritectic reaction product of C	Enthalpy of formation (kJ/mol)
				AlB₂	-67
Cr	CrB₂	-94
			Mo	MoB₂	-150
V	VB₂	-202
			Ta	TaB₂	-222
Nb	NbB₂	-251
			Ti	TiB₂	-280
Hf	HfB₂	-320
			Zr	ZrB₂	-326
W	W₂B₉	-375

In one embodiment, the additive includes, but is not limited to, chromium (Cr), molybdenum (Mo), vanadium (V), niobium (Nb), hafnium (Hf), zirconium (Zr), strontium (Sr), scandium (Sc), tantalum (Ta), tungsten (W), and any combination thereof. In another embodiment, the additive includes, but is not limited to, (Mo), vanadium (V), niobium (Nb), hafnium (Hf), zirconium (Zr), strontium (Sr), scandium (Sc), and any combination thereof. In another embodiment, the additive includes, but is not limited to, zirconium (Zr), strontium (Sr), scandium (Sc), and any combination thereof. In another embodiment, the additive comprises or consists of Cr. In another embodiment, the additive comprises or consists of Mo. In another embodiment, the additive comprises or consists of V. In another embodiment, the additive comprises or consists of Nb. In another embodiment, the additive comprises or consists of Ta. In another embodiment, the additive comprises or consists of W. In another embodiment, the additive comprises or consists of Hf. In another embodiment, the additive comprises or consists of Zr. In another embodiment, the additive comprises or consists of Sr. In another embodiment, the additive comprises or consists of Sc. In one embodiment, the additive comprises or consists of a combination of Zr and Sc. In another embodiment, the additive comprises or consists of a combination of Zr and Sr. In another embodiment, the additive comprises or consists of a combination of Sr and Sc. In another embodiment, the additive comprises or consists of a combination of Zr, Sr and Sc.

To provide the molten aluminum alloy, an additive, optionally titanium, is added to the molten aluminum or molten aluminum alloy. In some embodiments, it is contemplated to mix/stir the elements of the molten aluminum alloy to obtain a substantially homogeneous molten aluminum alloy. In an alternative or supplemental embodiment, it is contemplated that heat is applied to the molten aluminum alloy to obtain a substantially homogeneous molten aluminum alloy.

In some embodiments and as indicated above, an aluminum alloy containing titanium may be used. In such embodiments, it is not necessary to add titanium and additives (or a combination of additives) to the aluminum or aluminum alloy in a particular order. In one embodiment, the titanium is added to the molten aluminum/alloy first, and then the additives are added. In an alternative embodiment, the additive is added first to the molten aluminum/alloy, followed by the titanium. In another embodiment, titanium and additives are added simultaneously to the molten aluminum/alloy.

After providing the molten aluminum alloy, it is combined with a source of boron carbide, for example, a boron carbide powder (e.g., a free-flowing powder) to provide a molten composite comprising dispersed boron carbide particles. In a molten composite, it will be appreciated that the aluminum alloy (supplemented with additives and optionally titanium) is in molten form and the boron carbide particles are in solid form and at least partially associated with the products of the peritectic reaction. In some embodiments, it may be advisable to add a source of boron carbide (e.g., boron carbide powder) to the molten aluminum alloy described herein. In some embodiments, it is contemplated to mix/stir the elements of the molten composite to obtain a B-containing material having a dispersion₄A substantially homogeneous molten composite of C particles. The term "dispersed" means containing B₄The C particles are substantially uniformly distributed throughout the materialIn the matrix of the material. In some embodiments, consideration is given to allow proper wetting of B in the composite₄C particles are mixed/stirred.

The molten composite material has a fluidity that can withstand casting in an industrial environment due to the presence of peritectic reaction products. Flowability can be determined by various means as known to those skilled in the art. In one example, the fluidity is measured with a viscometer. In another example, fluidity is evaluated by measuring the length of a cast sample in a mold. To do so, it is possible to add an amount of B in a reactor (for example, a capacity of about 35 kg) containing a liquid aluminium-based mixture at a specific temperature (for example, about 700 ℃) to which a vacuum is applied₄And C, powder. The molten metal and B may be obtained using a progressive die having a predetermined length at fixed time intervals (e.g., every 20 minutes)₄C sample of a mixture of powders. In some embodiments, a K-die step die may be used. The fluidity is quantified as the distance reached/covered by the resulting mixture before curing. In some embodiments, the K-die may be a graphite coated stainless steel stepper die having a sample receiving chamber or recess with a width of 33mm (and in some embodiments a maximum length of 315mm) and inclined at an angle of about 10 °. For example, molten composite material that reaches a distance of 100mm after a holding time of 120 minutes in the K-mold described above is considered to have reasonable fluidity for direct cooling casting. In another example, molten composite material that reaches a distance of 190mm after a holding time of 120 minutes in the K-mold described above is considered to have excellent flowability for direct chill casting. In one embodiment, the flowability of the composite material is 190mm or greater after 120 minutes. In other embodiments, the composite has a flowability of 200mm or greater after 120 minutes. In one embodiment, the fluidity of the molten composite is at least 100mm when measured after a holding time of 120 minutes at a temperature of about 700 ℃. In embodiments, the composite material has a flowability of at least 105mm, 110mm, 115mm, 120mm, 125mm, 130mm, 1 when measured after a holding time of 120 minutes at a temperature of about 700 ℃35mm, 140mm, 145mm, 150mm, 155mm, 160mm, 165mm, 170mm, 175mm, 180mm, 181mm, 182mm, 183mm, 184mm, 185mm, 186mm, 187mm, 188mm, 189mm, 190mm, 191mm, 192mm, 193mm, 194mm, 195mm, 196mm, 197mm, 198mm, 199mm or 200 mm. In some embodiments, it is contemplated that the fluidity of the molten composite may vary depending on the holding time and holding temperature. In other embodiments, the fluidity of the composite material is not measured when the aluminum alloy is mixed with the boron carbide particles, but is measured after the peritectic reaction products have been formed or even the molten composite material is held at a particular temperature (e.g., holding temperature) and for a particular amount of time (e.g., holding time).

In embodiments, it is contemplated that a sample of the composite material is held at a particular temperature such that the material is in a molten state. In particular embodiments, the composite material is held at a minimum holding temperature equal to or greater than about 660 ℃, 670 ℃, 680 ℃, 690 ℃, 700 ℃, 710 ℃, 720 ℃, 730 ℃, 740 ℃, 750 ℃, 760 ℃, 770 ℃, 780 ℃, 790 ℃ or 800 ℃. In particular embodiments, the composite material is held at a maximum holding temperature at or below about 800 ℃, 790 ℃, 780 ℃, 770 ℃, 760 ℃, 750 ℃, 740 ℃, 730 ℃, 720 ℃, 710 ℃, 700 ℃, 690 ℃, 680 ℃, 670 ℃, or 660 ℃. In an alternative embodiment, the composite material is held at a temperature ranging between a minimum holding temperature as defined above and a maximum holding temperature as defined above.

In some embodiments, it is contemplated to hold a sample of the composite material in a molten state for a particular holding time. In particular embodiments, the composite is held for a minimum holding time equal to or greater than about 20 minutes, 30 minutes, 40 minutes, 50 minutes, 60 minutes, 70 minutes, 80 minutes, 90 minutes, 100 minutes, 110 minutes, 120 minutes, 130 minutes, 140 minutes, 150 minutes, 160 minutes, 170 minutes, 180 minutes, 190 minutes, or 200 minutes. In particular embodiments, the composite is held for a maximum hold time equal to or less than about 200 minutes, 190 minutes, 180 minutes, 170 minutes, 160 minutes, 150 minutes, 140 minutes, 130 minutes, 120 minutes, 110 minutes, 100 minutes, 90 minutes, 80 minutes, 70 minutes, 60 minutes, 50 minutes, 40 minutes, 30 minutes, or 20 minutes. In an alternative embodiment, the specific holding time range is between the minimum holding time as defined above and the maximum holding time as defined above.

In some embodiments, it is contemplated that the composite material is cast within a particular casting time. In particular embodiments, the composite material is cast for a minimum casting time equal to or greater than about 20 minutes, 30 minutes, 40 minutes, 50 minutes, 60 minutes, 70 minutes, 80 minutes, 90 minutes, 100 minutes, 110 minutes, 120 minutes, 130 minutes, 140 minutes, 150 minutes, 160 minutes, 170 minutes, 180 minutes, 190 minutes, or 200 minutes. In particular embodiments, the composite material is cast for a maximum casting time equal to or less than about 200 minutes, 190 minutes, 180 minutes, 170 minutes, 160 minutes, 150 minutes, 140 minutes, 130 minutes, 120 minutes, 110 minutes, 100 minutes, 90 minutes, 80 minutes, 70 minutes, 60 minutes, 50 minutes, 40 minutes, 30 minutes, or 20 minutes. In an alternative embodiment, the specific casting time range is between the minimum casting time as defined above and the maximum casting time as defined above.

The molten composite may be subjected to any form of casting (including DC casting of billets or slabs), casting of ingots for future remelting and casting, and casting into shapes using any suitable form of shape casting. The cast composite can be further processed and is well suited for further operations such as (a) remelting and casting shapes, (b) extrusion, and (c) rolling or (d) forging.

The methods described herein can be used to prepare aluminum boron carbide composites of any shape, particularly containing high levels of B₄Those of C. Advantageously, in some embodiments, lower grades of B may be used in the presence of additives₄C powder without significant change of molten Al-Ti-B₄And C, the fluidity of the compound.

The invention will be more readily understood by reference to the following examples, which are given to illustrate the invention without limiting its scope.

Example I

Primary aluminum metal alloy (AA1100) was melted in a reactor at a temperature of 765 ℃. Ti was added, followed by Sr. Thereafter, B is added₄The C particles are injected into the melt. The final concentrations of both Ti and Sr were 1.65 wt%. B is₄The final concentration of C particles was 28 vol%.

The final mixture was held at a temperature of about 700 ℃ and two fluidity samples were obtained every 20 minutes. The flowability measurements are shown in table 2.

TABLE 2 flowability measurements from example I.

Time (min)	Fluidity measurement value #1(mm)	Fluidity measurement value #2(mm)
			5	161	170
20	179	172
			47	185	194
65	199	193
			80	186	180
100	180	186
			120	205	191

The results shown in table 2 indicate that after a holding time of 120 minutes, the flowability was higher than 190mm, allowing industrial casting of composite materials.

Example II

Primary aluminum metal alloy (AA1100) was melted in a reactor at a temperature of 765 ℃. Zr was added. Thereafter, B is added₄The C particles are injected into the melt. The final concentration of Zr was 3.8 wt.%. B is₄The final concentration of C particles was 19 vol%.

The final mixture was maintained at a temperature of about 700 ℃, and two fluidity samples were obtained at various time intervals. The resulting flowability measurements are shown in table 3.

TABLE 3 flowability measurements from example II.

Time (min)	Measured value of flowability (mm)
		10	260
20	280
		40	295
60	306
		80	291
100	200
		120	210

The results shown in table 3 indicate that after a holding time of 120 minutes, the flowability was higher than 190mm, allowing industrial casting of composite materials.

While the invention has been described in connection with specific embodiments thereof, it should be understood that the scope of the claims should not be limited by the preferred embodiments set forth in the examples, but should be given the broadest interpretation consistent with the description as a whole.

Claims

1. A method of making a cast composite material, the method comprising:

(a) combining (i) a molten aluminium alloy AA1100 comprising an additive capable of undergoing a peritectic reaction with boron and (ii) a source of boron carbide particles to provide a molten composite material comprising between 4% and 40 vol% boron carbide and a product of the peritectic reaction between the additive and boron and dispersed boron carbide particles, based on the volume of the cast composite material, wherein:

the additive is selected from the group consisting of chromium, molybdenum, vanadium, niobium, zirconium, strontium, scandium, and any combination thereof, with the proviso that the additive is not titanium; and is

A sample of the composite material has fluidity after having been heated to a temperature of about 700 ℃ for about 120 minutes before casting, corresponding to a cast length of at least 100mm when measured using a mould having a groove for receiving the sample, the groove having a width of about 33mm, a height of between about 6.5mm and about 4.0mm, and being inclined downwardly from a horizontal axis by about 10 °; and

(b) casting the molten composite to form the cast composite material.

2. The method of claim 1, wherein the cast length is at least 190 mm.

3. The method of claim 1 or 2, further comprising, prior to step (b), holding the molten composite material for a holding time and casting the molten composite for a casting time, wherein the combination of the holding time and the casting time is at least 120 minutes.

4. The method of any one of claims 1-3, further comprising, prior to step (a), providing the molten aluminum alloy by combining molten aluminum or a molten aluminum alloy with the additive.

5. The method of any one of claims 1-4, wherein the additive is selected from the group consisting of zirconium, strontium, scandium, and any combination thereof.

6. The method of any one of claims 1 to 5, wherein the additive is scandium.

7. The method of any one of claims 1 to 6, wherein the additive is strontium.

8. The method of any one of claims 1 to 7, wherein the additive is zirconium.

9. The method of claim 1, wherein the concentration (w/w) of the additive is between 0.47% and 8.00% based on the total weight of the cast composite material.

10. The method of any one of claims 1 to 8, wherein the concentration (v/v) of the dispersed boron carbide particles is between 4.5% and 18.9% based on the total volume of the cast composite material.

11. The method of claim 10, wherein the concentration (w/w) of the additive is between 0.38% and 4.00% based on the total weight of the cast composite material.

12. The method of any one of claims 1 to 8, wherein the concentration (v/v) of the dispersed boron carbide particles is between 19.0% and 28.0% based on the total volume of the cast composite material.

13. The method of claim 12, wherein the concentration (w/w) of the additive is between 1.68% and 6.00% based on the total weight of the cast composite material.

14. The method of any one of claims 1 to 8, wherein the concentration (v/v) of the dispersed boron carbide particles is between 25.0% and 28.0% based on the total volume of the cast composite material.

15. The method of any one of claims 1 to 8, wherein the concentration (v/v) of the dispersed boron carbide particles is between 28.0% and 33.0% based on the total volume of the cast composite material.

16. The method of claim 14 or 15, wherein the concentration (w/w) of the additive is between 0.94% and 4.00% based on the total weight of the cast composite material.

17. A method of improving the casting and/or shaping characteristics of a molten composite material comprising (i) an aluminium alloy AA1100, (ii) a product of a peritectic reaction between an additive and boron, and (iii) between 4% and 40 vol% dispersed boron carbide particles, based on the volume of the cast composite material, the method comprising combining (a) a molten aluminium alloy comprising the additive capable of undergoing the peritectic reaction with boron, with (b) a source of boron carbide particles, to provide a molten composite material, wherein:

A sample of the composite material has a fluidity after having been heated to a temperature of about 700 ℃ for about 120 minutes before casting, corresponding to a casting length of at least 100mm when measured using a mould having a groove for receiving the sample, the groove having a width of about 33mm, a height of between about 6.5mm and about 4.0mm, and being inclined downwardly from a horizontal axis by about 10 °.

18. The method of claim 17, wherein the cast length is at least 190 mm.

19. A method of promoting the formation of a molten composite material comprising (i) an aluminium alloy AA1100, (ii) a product of a peritectic reaction between an additive and boron, and (iii) between 4% and 40% by volume, based on the volume of the cast composite material, of dispersed boron carbide particles, the method comprising combining (a) a molten aluminium alloy comprising the additive capable of undergoing the peritectic reaction with boron, and (b) a source of boron carbide particles, to provide a molten composite material, wherein:

20. The method of claim 19, wherein the cast length is at least 190 mm.