US3037857A

US3037857A - Aluminum-base alloy

Info

Publication number: US3037857A
Application number: US819018A
Authority: US
Inventors: Louis A Conant
Original assignee: Union Carbide Corp
Current assignee: Union Carbide Corp
Priority date: 1959-06-09
Filing date: 1959-06-09
Publication date: 1962-06-05
Anticipated expiration: 1979-06-05

Description

3,037,857 ALUMINUM-BASE ALLOY Louis A. Conant, Tonawauda, N.Y., assignor to Union Carbide Corporation, a corporation of New York No Drawing. Filed June 9, 1959, Ser. No. 819,018

' 16 Claims. (Cl. 75-138) This invention relates to low density alloys having a high modulus of elasticity and, more particularly, to an aluminum-base alloy and a method of producing said lalloy.

Aluminum alloys and other low density alloys have been the chief structural materials for applications requiring high strength-to-weight ratios in their construction materials. This has been especially the case in the airc'raft'industry where designers are now faced with the added problem of providing light-weight structural materials capable of withstanding the higher stresses associated with todays high speed aircraft and missiles.

'In the selection of structural materials, however, other factors than strength-to-weight ratios must be considered. For example, the resistance to elastic deformation of the structural material must be considered. The resistance of a material to elastic deformation is known as stifiness and represents the extent of the elastic deformations or deflections which take place under given stresses. The most desirable structural material should not only be capable of withstanding high stresses, but should also exhibit relatively little deformation under these stresses. This resistance to elastic deformations is measuredby the value of the modulus of elasticity of the material and is a separate function of the yield point or ultimate strength of the material. The actual deformations or deflections produced in stressed member depend on the modulus of elasticity of the material and the geometry of the member. It is often necessary, especially in structures made of aluminum, to design the members on the basis of their stiffness rather than on their strength. Many members are designed with larger cross-sections than are required to carry the given stresses because the larger cross-section is needed to give the structure the required stiffness. Because many low-density alloys, such as aluminum alloys, have a comparatively low-modulus of elasticity, the savings in weight that could be realized by the use of these materials is often offset by the need to design and use larger sections to provide the necessary stiffness.

The modulus of elasticity of pure aluminum is about -)(10 pounds per square inch while the modulus of elasticity of steel is about 30X 10 pounds per square inch.

Considerable effort has been spent in attempting to achieve a low density alloy having a high modulus of elasticity by incorporating in the metal a second phase material with an intrinsic modulus higher than that of any intermetallic compound that might be produced by the usual alloying elements. Intermetallic and refractory compounds suoh as titanium carbide, silicon carbide, and boron carbide, have been added to aluminum to increase the modulus of elasticity but the degree of improvement has not amounted to more than 28 percent.

Another factor to be considered in the selection of structural materials is the coefficient of expansion of the material. An excessively high rate of expansion can limit the usefulness of the material and a low coeflicient of expansion is therefore desirable. Unfortunately many low-density alloys have high coefficients of expansion.

It is the primary object of this invention, therefore, to provide an =aluminum-base alloy having a higher modulus of elasticity than pure aluminum and heretofore produced aluminum-base alloys.

It is also an object of this invention to provide an alu- Patented June 5, 1962 2 minum-b-ase alloy having a high ratio of modulus of elasticity-to-density. I

It is a further object of this invention to provide an aluminum-base alloy having a lower coefficient of expansion than pure aluminum and many heretofore produced aluminum alloys. a

It is also an object of this invention to provide an aluminum alloy having a high strength-to-density ratio and which is suitable for use in applications requiring high Wear resistance.

It is a further object of this invention to provide a method for producing the aluminum-base alloy described herein.

Other aims and objects of this invention 'will be apparent from the following description and appended claims.

In accordancewith these objects a method for producing a high modulus aluminum-base alloy is provided which comprises dispersing finely divided particles of a refractory metal boride in an aluminum matrix. The process of the invention comprises preparing a mixture consisting essentially of from about 5 to about 50 volume percent of particles of borides of at least one metal selected from the group consisting of titanium, chromium, zirconium, tantalum, columbium, hafnium, vanadium and molybdenum, and the balance powdered aluminum material selected from the group consisting of aluminum and aluminum alloys, compacting the resulting mixture into a coherent slug, heating the resulting slug in the absence of air to a temperature at which the powdered aluminum material melts without substantial vaporization and below the melting point of the metal borides, and allowing the slug to cool. In a preferred embodiment the slug is cooled to :a temperature below the freezing point of the aluminum material and worked into a desired shape by rolling, extrusion, forging, etc.

In the practice of the process of this invention an alloy is produced consisting essentially of from about 5 to about 50 volume percent of particles of borides of at least one metal selected from the group consisting of titanium, chromium, zirconium, tantalum, columbium, hafnium, vanadium and molybdenum, and the balance substantially all of a metal selected from the group consisting of aluminum and aluminum alloys, said particles of metal borides being dispersed in a continuous matrix of the selected metal.

Specifically an alloy is provided consisting essentially of from about 5 to 50 volume percent of titanium diboride dispersed in a continuous matrix of aluminum or an aluminum-base alloy.

-A summary of the properties of the alloy of this invention, as compared to the properties of representative aluminum alloys, is presented in Table I. As may be seen from the table, the specific modulus, or ratio of modulus of elasticity-to-density, of the alloy of the invention, containing as little as 10 percent by volume of a dispersed phase of titanium diboride is increased by more than 15 percent. The resulting modulus of elasticity of this alloy is greater than that of some of the best commercial aluminum alloys as listed in Table I. When the amount of the dispersed titanium diboridephase is increased to 45 percent by volume of the alloy, the increase in specific modulus over the best commercial aluminum alloy is nearly 79 per cent.

The commercial aluminum I have the following compositions. Alloy I is a sintered aluminum product containing 8 percent A alloy II contains 6.0 percent copper, 0.3 percent manganese, 0.11 percent vanadium, and 0.15 percent zirconium; alloy III contains 4.5 percent copper, 1.5 percent magnesium, and 0.6 percent manganese; alloy IV contains 12.2 percent silicon, 0.9 percent copper, 1.1 percent magneisum, and

alloys referred to in Table in; a) 0.9 percent nickel; alloy V contains 6.3 percent silicon, and 3.5 percent copper.

hearing materials and Wcanresistant materials, especially at elevated temperatures. A particular use for this alloy TABLE I 10 vol. 20 TiBn- 30 T1133 40 TiBz- 45 vol. percent Al, 29 Al, 42 A percent T1131, 16 weight weight weight T1132. 57 Alloy Alloy Alloy Alloy Alloy weight percent percent percent weight I II III IV V percent T1132 T1131 T1137 percent TiB; TlBl Tensile Strength:

Ultimate 75 F 18, 500 25, 000 33,000 45,000 55, 000 37, (100 62, 000 68, 000 55, 000 36, 000 Yield 75 F 13, 500 13, 000 18, 500 27, 000 37, 000 24, 000 43, (100 47, 000 46, 000 24, 000

31.0 45. 0 22. 0 7.0 4.0 750 F 45. 0 68.0 38.0 14. 0. 11.0 Modulus of elasticity p.s.l. x 10 2 16. 1 3 18. 4 3 20.0 2 26. 5 10. 6 10. 5 10.6 11.4 10. 3

75 F 2 13. 5 3 16. 3 20. 0 2 22. 5 26. 3 750 F 3 12. 8 3 17.66 I- 6.6 Density g./cc. (ealc. mech. mixture) 2.88 3.06 3. 24 3. 42 3. 5 2. 74 2. 8 2. 77 2. 69 2. 79 Specific modulus (mod. of elas./density) 4.7 5; 3 5. 9 6. 3 7. 5 3. 9 3. 3. 8 4. 2 3.7 Thermal coellicient of linear expansion 0.

x 10'", -100 0 16. 15. 96 13. 97 11. 97 4 23. 0 l 22. 0 22. 8 19, 4 22.0 Condition 1 Test conducted at 700 F. 2 Huggenberg extensometer. 3 Sonic test. Approximately. 5 Cast forged rolled.

" As extruded, does not require heat treatment. 1 As extruded.

"Forged Solution heat treated and aged.

The data presented in the table shows that by varying the amount of titanium diboride phase present in the matrix, a series of materials of different properties can be obtained. It is to be noted that the modulus of elasticity of a volume percent titanium diboride-aluminum alloy is almost double that of pure aluminum and that the modulus of a 45 volume percent titanium diboridealuminum alloy approaches the:value of the modulus of elasticity of steel. llt is also to be noted that the strength of the to volume percent titanium diboridealuminum alloy compares favorably with such commercial alloys as alloy I (containing 8 percent by weight A1 0 powder) and alloy II (6 percent copper, 0.3 percent manganese, 0.11 percent vanadium, and 0.15 percent zirconium). It has also been found that when titanium diboride or other metal borides are dispersed in high-strength commercial aluminum alloys such as those listed in Table I, a superior high-modulus alloy results.

Another feature of the alloy of this invention is its low coeificient of linear expansion in comparison with commercial aluminum alloys and carbon steels. The coefficients of linear thermal expansion for several materials are presented in Table II. A 45 volume percent titanium diboride-aluminum alloy has a coefiicient about equal to that of carbon steel and only one half the normal coefficient of expansion of pure aluminum.

1 Approximately. 2 20500 C.

The alloys of this invention do not require further heat treatments to achieve their full properties. The alloys can also be easily fabricated and possess a ductility ranging from good to high.

The alloys of this invention have utility as heavy-duty 5 Solution heat treated and aged.

Cast solution heat treated and aged.

is to be found in pistons in engines. Since the titanium diboride-aluminum alloys can be readily Welded and since they have the high elastic modulus required for thin stiff sections, and possess a low coeflicient of expansion, they are suitable for use as a material of construction in cryogenic apparatus and containers. The usefulness of the alloys of this invention is further enhanced by their similarity to steels, especially with regard to the important properties of modulus of elasticity and coefficient of thermal expansion. This invention provides a light-weight structural alloy which is mechanically compatible with steel enabling both to be employed cooperatively in a wide variety of applications which previously were not possible.

The production of alloys having a high elastic modulus-to-density ratio is accomplished by dispersing finely divided particles of a metal boride in a low melting, ductile, light metal matrix such as an aluminum matrix. In order to assure that the desired cilect is permanent, it is necessary that the constituents be mutually nonreactive and insoluble in each other. It has been found that, besides titanium diboride, zirconium and chromium diboride are also unreactive and insoluble in aluminum. The diborides of tantalum, columbium, hafnium, vanadium and molybdenum are all relatively insoluble and nonreactive in aluminum.

The dispersed phase mustbe not only unreactive and insoluble in the matrix, but it must also be subject to an intimate bond with the matrix under the varying temperature and pressure conditions of the metalworking operation. These conditions are particularly well met by the combination of a titanium diboride phase dispersed in an aluminum or aluminum alloy matrix. The aluminum completely wets the titanium diboride and yet shows no tendency to react chemically with it. For example, when titanium diboride is contacted with molten aluminum at 246-2 R, an X-ray analysis reveals no evidence of reaction between the two. The unique character of the mixture is further illustrated by the fact that when an unsupported slug of the compacted powders, in which the low melting aluminum matrix occupies as much as percent of the volume, is heated above the melting point of the aluminum, and maintained in that condition, the slug, although apparently molten, retains its original shape "and does not slump into a formless pool of molten aluminum. This effect, believed to be caused by a strong tendency of the aluminum to wet the diboride phase, is

also believed to be responsible for the excellent degree of dispersion of the diboride particles in the aluminum matrix. Since heating is carried out in a vacuum or inert atmosphere, the fact that no gross melting occurs cannot be attributed to the presence of oxide or oxide coating acting as a skin to hold the shape of the article.

Melting or foundry techniques have also been used to prepare dispersions of titanium diboride in aluminum or aluminum alloys. This method is particularly advantageous in the preparation of materials with lower percentages of metal borides-up to about 20 percent by volume. Ten and fifteen percent by volume titanium diboride dispersions in aluminum have been prepared by melting ingot aluminum together with a titanium diboride powder at a temperature of about 1200 C. in a vacuum or argon atmosphere. The molten material was then poured into a steel mold to form an ingot 1% by 3 inches.

It has been found that the addition of about 2 percent by volume of misch metal to such a molten bath of aluminum and titanium diboride greatly aids in the suspension and dispersion of the titanium diboride. Misch metal is a combination of rare earth metals consisting primarily of cerium and lanthanum. The misch metal may increase the fluidity of the molten aluminum.

The most uniform dispersions of the titanium diboride phase in an aluminum matrix have been obtained by the use of a new technique combining compaction and controlled melting.

In this process, the powders of the diboride and the aluminum material are dry blended and cold compacted at a pressure of from about 30,000 to about 50,000 pounds per square inch into a slug of convenient dimensions. The powders of titanium diboride have an average size between 1.0 and 0.01 micron or finer. However the particle size may range up to 10 microns. The alumi-.

num material may be powdered or atomized aluminum. Atomized aluminum is the powder produced by spraying molten aluminum and cooling it rapidly to form a powder. The slug is heated, in a vacuum or in an inert atmosphere, to between 1000 and 1150 C., which is far in excess of the melting point of aluminum (660 0). Gross melting does not occur, probably as the result of capillarity due to the wetting of the titanium diboride particles by the molten aluminum.

While ordinary powder metallurgical techniques, such as cold pressing and sintering, or hot pres-sing can be used to produce articles of this alloy they do not produce the same superior alloy product as the compactioncontrolled melting technique described herein. Although to all outward appearances the constitution of the alloy is the same, the two products have different properties. When identical mixtures of titanium diboride and aluminum powders are subjected to the same fabricating procedures, except that hot pressing is substituted for the compaction-controlled melting technique, the modulus of elasticity of the products differ. The sintered or hot pressed product has a modulus of only about 13x10 pounds per square inch while the product produced by the process of this invention has a modulus of about 16 10 pounds per square inch.

Since a dense, strong material is produced after the firing operation, it is practical to use the product in the as-fired condition, or to fabricate the as-fired composition by rolling, forging or swaging without the necessity of first extruding the product. This is in contrast to the present practice of forming aluminum materials by powder metallurgical techniques which requires an extrusion step following the compaction of the powder in order to densify the material.

The as-fired compact or ingot can also be directly rolled or worked by forging to produce a variety of articles. For example, hot-rolled sheet of 0.030 inch thickness has been produced from a composition containing volume percent titanium diboride. This sheet was then further reduced to 0.005 inch thickness by coldrolling.

When the fired product is extruded, it can be fabricated into useful shapes by conventional working techniques.

The alloy of this invention can be readily welded. During the welding operation the melted portion of the article does not lose its dispersed phase as do many other aluminum materials produced by powder metallurgical techniques. After the alloy of this invention is welded, the dispersion of titanium diboride is the same in. the heated zone as it is in the unheated zone.

It is also possible to weld or heat small cracks or other imperfections by heating the titanium diboridealuminum material above its melting point;

The following examples are presented to illustrate the practice of the invention.

Example I Fifty two percent by weight (40 volume percent) of dry, finely divided titanium diboride was blended with 48 percent by Weight (60 volume percent) of atomized aluminum, and the mixture was cold compacted at 30,000 p.s.i. into FA -inch diameter slugs approximately 2 /2 inches long. A slug was heated under vacuum conditions to 1150 C., or approximately 472 C. above the melting point of the aluminum, and held there for about 15 minutes. Gross melting did not occur but rather the slug retained its shape while the molten aluminum flowed completely in and around each particle of titanium diboride producing thereby the desired dispersion. After this heat treatment, the slug was cooled below the point at which the aluminum solidified, and removed to an extrusion press where it was reduced from a FA -inch ingot to a rod inch in diameter, or a 16:1 reduction in area, by the application of about 30,000 p.s.i. The density of the rod in the as-extruded condition was about 3.42 g./ cc. and it exhibited a Youngs modulus of elasticity at 75 F. of about 22.5 X 10 p.s.i. as determined by a Huggenberg Extensometer. The coefiicient of linear expansion in the range of 20 to 100 C. was found to be 13.97 10 These and other properties are contained in Table 1.

Example II Sixteen percent by weight (10 volume percent) of finely divided titanium diboride was dry blended with 84 percent by weight volume percent) of atomized aluminum and 2 percent by weight misch metal. The mixture was melted in an A1 0 crucible at 2336 F. and 200 microns pressure. The melt was then cast into a steel mold, forming an ingot 1% inches in diameter by 2% inches long. The ingot was hot forged and rolled at 900 F. into a cylindrical rod inch in diameter. Specimens were cut from the rod and subjected to physical property tests. The results of these tests are given in Table I.

Example III The general procedure of Example I Was employed except as follows. A commercial aluminum alloy containing 94.5 percent aluminum, 4.5 percent magnesium, and 0.75 percent manganese was used as the base material. Two compositions of this alloy with titanium diboride additions were prepared. Composition A contained 23.3 percent by weight titanium diboride ("15 percent by volume), 72.5 percent by weight aluminum, 3.5 percent by weight magnesium, and 0.7 percent by weight manganese. Composition B contained 36.2 percent by weight titanium diboride (25 percent by volume), 60.2 percent by weight aluminum, 3.0 percent by weight magnesium, and 0.6 percent by weight manganese. These compositions were heated at a temperature of 900 C.

The strength properties of these compositions are shown in Table III. Specimens of the composition were tested in the as-extruded condition as well as the extruded and swaged condition. Also presented in the table are the published strength values of the commercial alloy base material and the values for two aluminum-titanium diboride alloysa 20% volume titanium diboride-aluminum alloy and a 30% volume titanium diboride-aluminum alloy. It can be seen that the swaging produces a strain-hardened condition that significantly increases the yield strength and to a lesser extent the ultimate strength. The ductility as measured by the elongation in the swaged samples has decreased, but ductility measured by contraction, or reduction in area has remained unchanged or, in some cases, increased.

group consisting of titanium, chromium, zirconium, tantalum, columbium, hafnium, vanadium and. molybdenum, and the balance at least one powdered aluminum material selected from the group consisting of aluminum and aluminum alloys, compacting the resulting mixture into a coherent slug, heating the resulting slug in the absence of air at a temperature at which the aluminum material melts without substantial vaporization and below the melting temperature of the metal borides, cooling the Other physical properties are presented in Table Illa. 10 slug to a temperature below the freezing temperature of TABLE III STRENGTH PROPERTIES OF TITANIUM DIBORIDE-ALUMINUM MATERIALS Tensile Strength Per- Per- 75 F. temper- Per- 750 F. tempercent cent Composition Condltion ature Per" cent ature elongareduccent reducatlon tlon in elongation in area Yield Ultition area Yield Ultimate mate Commercial alloy Strain hardened 33, 000 46, 000 16 Composition A. As extruded 28, 500 48, 300 8 Do Extruded and swaged- 56, 300 63, S 2. Composition B As extruded 36, 000 60,000 6 o Extruded and swaged. 52, 000 G3, 000 2.0 vol. TiB and aluminum alloy.. As extruded 13,000 25, 000 24 Do Extruded and swaged. 23,500 28,000 12 vol. T113 and aluminum alloy- Extruded 18, 500 33, 000 16 Do Extruded and swaged 35, 000 36, 500 5 1 Not tested.

TABLE IIIa PHYSICAL PROPERTIES OF TITANIUM: DIBORIDE- ALUMINUM MATERIALS the selected aluminum material, and forming the slug into a desired shape.

2. The method of preparing an aluminum-base alloy product characterized by an increased modulus of elaslg/Iodt? D Specfic Thermal co eigeier ig of ticity and a decreased c oeflicient of thermal expansion Composition ggg ,2; E i ewansmn which comprises preparing a mixture consisting essenity 9/ec. modubelly of from about 5 to about 50 volume percent of parg-ig 395 a g g ticles of borides of at least one metal selected from the group consisting of titanium, chromium, zirconium, tancommercialauoym 10.3 264 39 24 26 (1) talum, columbium, hafnium, vanadium and molybde- Composition 16.0 2.92 5.5 17.7 21.6 num, and the balance at least one powdered aluminum g i vg ll i B gf w material selected from the group consisting of aluminum aluminum a l y- 16.0 6 16-25 18.32 and aluminum alloys, compacting the resulting mixture 'g 19.0 3.24 1&9 118 into a coherent slug having a desired shape, heating the resulting slug in the absence of air at a temperature at Not tested which the aluminum material melts without substantial vaporization and below the melting temperature of the Example 1V metal borides, and cooling the slug.

In general, the procedure of Example I Was followed except that 37.13 parts by weight (30 volume percent) of chromium diboride powder was blended with 41.87 parts by weight (70 volume percent) of atomized aluminum. Results are given in Table IV below for room temperature conditions.

TABLE IV Yield Ultimate Elongation, Reduction Modulus of strength, strength percent area, elasticity,

p.s.i. p.s.i. percent p.s.i. x 10' 3. The method of preparing an aluminum-base alloy product characterized by an increased modulus of elasticity and a decreased coefiicient of thermal expansion which comprises preparing a mixture consisting essentially of from about 5 to about 50 volume percent of particles of borides of at least one metal selected from the group consisting of titanium, chromium, zirconium, tantalum, columbium, hafnium, vanadium and molybdenum, and the balance at least one powdered aluminum material selected from the group consisting of aluminum and aluminum alloys, compacting the resulting mixture at a pressure of from about 30,00 to 50,000 pounds per square inch into a slug having a desired shape, heating the resulting slug in the absence of air at a temperature between the melting temperature of the selected aluminum material and about 1350" C., and cooling the slug.

4. The method of preparing an aluminum-base alloy product characterized by an increased modulus of elasticity and a decreased coeiiicient of thermal expansion which comprises preparing a mixture consisting essentially of from about 5 to about 50 volume percent of parrticles of borides of at least one metal selected from the group consisting of titanium, chromium, zirconium, tantalum, columbium, hafnium, vanadium and molybdenum, said particles having an average size up to about 10 microns, and the balance at least one powdered aluminum material selected from the group consisting of aluminum and aluminum alloys, compacting the resulting mixture at a pressure of from about 30,000 to 50,000 pounds per square inch into a slug, heating the resulting slug in the absence of air at a temperature between the melting temperature of the selected aluminum material and about 1350 C., cooling the slug to a temperature below the freezing temperature of the selected aluminum material, and forming the slug into a desired shape.

5. The method of preparing an aluminum-base alloy product characterized by an increased modulus of elas ticity and a decreased coefficient of thermal expansion which comprises preparing a mixture consisting essentially of from about 5 to about 50 volume percent of particles of borides of at least one metal selected from the group consisting of titanium, chromium, zirconium, tantalum, columbium, hafnium, vanadium and molybdenum, and the balance at least one powdered aluminum material selected from the group consisting of aluminum and aluminum alloys, compacting the resulting mixture at a pressure of from about 30,000 to 50,000 pounds per square inch into a slug, heating the resulting slug in the absence of air at a temperature between the melting temperature of the selected aluminum material and 115 C., cooling the slug to a temperature below the freezing temperature of the selected aluminum material, and forming the slug into a desired shape.

-6. The method of preparing an aluminum-base alloy product characterized by an increased modulus of elasticity and a decreased coefficient of thermal expansion which comprises preparing a mixture consisting essentially of from about to about 50 volume percent of particles of titanium diboride, and the balance substantially all powdered aluminum, compacting the resulting mixture into a coherent slug, heating the resulting slug in the absence of air at a temperature at which the aluminum melts without substantial vaporization and below the melting temperature of the metal borides, cooling the slug to a temperature below the freezing temperature of the aluminum, and forming the slug into a desired shape.

7. The method of preparing an aluminum-base alloy product characterized by an increased modulus of elasrticity and a decreased coefficient of thermal expansion which comprises preparing a mixture consisting essentially of from about 5 to about 50 volume percent of particles of titanium diboride, and the balance substantially all powdered aluminum, compacting the resulting mixture into a coherent slug having a desired shape, heating the resulting slug in the absence of air at a temperature at which the aluminum melts without substantial vaporization and below the melting temperature of the metal boride for at least a time sufficient for the aluminum to melt, and cooling the slug.

8. The method of preparing an aluminum-base alloy product characterized by an increased modulus of elasticity and a decreased coefficient of thermal expansion which comprises dry blending a mixture consisting essentially of from about 5 to about 50 volume percent of particles of titanium diboride, and the balance substantially all powdered aluminum, compacting the resulting mixture at a pressure of from about 30,000 to about 50,000 pounds per square inch into a slug having a desired shape, heating the resulting slug in the absence of air at a temperature between about 660 C. and 1150 C., and cooling the slug.

9. The method of preparing an aluminum-base alloy product characterized by an increased modulus of elasticity and a decreased modulus of thermal expansion which comprises preparing a mixture consisting essentially of from about 5 to about 50 volume percent of particles of titanium diboride having an average size up to about microns, and the balance substantially all atomized aluminum, compacting the resulting mixture at a pressure of from about 30,000 to about 50,000 pounds per square inch inch into a slug, heating the resulting slug in the absence of air at a temperature between the melting temperature of the aluminum and 1350 C., cooling the slug to a temperature below the freezing temperature of the aluminum, and forming the slug into a desired shape.

10. The method of preparing an aluminum-base alloy product characterized :by an increased modulus of elasticity and a decreased modulus of thermal expansion which comprises preparing a mixture consisting essentially of from about 5 to about 50 volume percent of particles of titanium diboride having an average size up to about 10 microns, and the balance substantially all atomized aluminum, compacting the resulting mixture at a pressure of from about 30,000 to about 50,000 pounds per square inch into a slug, heating the resulting slug in the absence of air at a temperature between about 660 C. and 1150 C., cooling the slug to a temperature below the freezing temperature of the aluminum, and forming the slug into a desired shape.

11. The method of preparing an aluminum-base alloy product, characterized by an increased modulus of elasticity and a decreased coeificient of thermal expansion which comprises preparing a mixture consisting essentially of from about 5 to about 50 volume persent of particles of borides of at least one metal selected from the group consisting of titanium, chromium, zirconium, tantalum, columbium, hafnium, vanadium, and molybdenum, and the balance at least one powdered aluminum material selected from the group consisting of aluminum and aluminum alloys, melting the resulting mixture in the absence of air, and casting the molten .alloy into a desired shape.

12. The method of preparing an aluminum-base alloy product characterized by an increased modulus of elasticity and a decreased modulus of thermal expansion which comprises preparing a mixture consisting essentially of from about 5 to about 50 volume percent of particles of titanium diboride, and the balance substantially all powdered aluminum, melting the resulting mixture in the absence of air, and casting the molten alloy into a desired shape.

13. The method of preparing an aluminum-base alloy product characterized by an increased modulus of elasticity and a decreased modulus of thermal expansion which comprises preparing a mixture consisting essentially of from about 5 to about 50 volume percent of particles of titanium diboride, and the balance substantially all powdered aluminum, melting the resulting mixture in the absence of air, casting the molten alloy into an ingot, and forming the ingot into a desired shape.

14. The method in accordance with claim 13 wherein the ingot is formed by extrusion.

15. A fused alloy product produced by preparing a mixture consisting essentially of from 5 to 50 volume percent of particles of borides of at least one metal selected from the group consisting of titanium, chromium, zirconium, tantalum, columbium, hafnium, vanadium, and molybdenum, and the balance at least one powdered aluminum material selected from the group consisting of aluminum and aluminum alloys, compacting the resulting mixture into a coherent slug, heating the resulting slug in the absence of air at a temperature at which the aluminum material melts without substantial vaporization and below the melting temperature of the metal borides, and cooling the slug to a temperature below the freezing temperature of the selected aluminum material.

16. The fused .alloy product produced in accordance with claim 15 in which the selected boride is titanium diboride.

(References on following page) References Cited in the file of this patent UNITED STATES PATENTS Southard Dec. 11, 1951 Conant Mar. 5, 1957 Glaser Aug. 13, 1957 Grant Feb. 18, 1958 Nachtman July 1, 1958 12 Goetzel et a1. Sept. 16, 1958 Dubeck Nov. 17, 1959 OTHER REFERENCES Metal Powder Report, vol. 11-12 (September 1956- August 1958), pp. 144 and 145.

The Iron Age, Jan. 20, 1949, pp. 66-7().

Journal of Metals, March 1959, pp. 189494.

Claims

15. A FUSED ALLOY PRODUCT PRODUCED BY PREPARING A MIXTURE CONSISTING ESSENTIALLY OF FROM 5 TO 50 VOLUME PERCENT OF PARTICLES OF BORIDES OF AT LEAST ONE METAL SELECTED FROM THE GROUP CONSISTING OF TITANIUM, CHROMIUM, ZIRCONIUM, TANTALUM, COLUMBIUM, HAFNIUM, VANADIUM, AND MOLYBDENUM, AND THE BALANCE AT LEAST ONE POWDERED ALUMIUM MATERIAL SELECTED FROM THE GROUP CONSISTING OF ALUMIUM AND ALUMINUM ALLOYS, COMPACTING THE RESULTING MIXTURE INTO A COHERENT SLUG, HEATING THE RESULTING SLUG IN THE ABSENCE OF AIR AT A TEMPERATURE AT WHICH THE ALUMONUM MATERIAL MELTS WITHOUT SUBSTANTIAL VAPORIZATION AND BELOW THE MELTING TEMPERATURE OF THE METAL BORIDES, AND COOLING THE SLUG TO A TEMPERATURE BELOW THE FREEZING TEMPERATURE OF THE SELECTED ALUMINUM MATERIAL.