Metal matrix composites of aluminum, magnesium and titanium using calcium hexaboride

Abstract

A metal matrix composite was fabricated by adding particles of calcium hexaboride to a metal of aluminum, magnesium or titanium and their alloys. The resulting metal matrix composite is light weight has improved strength, increased elastic modulus and reduced thermal coefficient of expansion, thus making the metal matrix composite more useful in industry.

Description

[0001] The present invention relates generally to the improved mechanical and physical properties including strength, elastic modulus and reduced thermal expansion of metal bodies by using metal matrix composites, and more particularly to the reinforcement of aluminum, magnesium and titanium by forming metal matrix composites of these metal using calcium hexaboride particles.[0002] The light weight metals of aluminum and magnesium have very large markets for they are utilized in a wide variety of industries. In a lesser way, titanium is also utilized as a light weight fabrication material. These metals suffer from some drawbacks, however, which limit their usefulness. These include low stiffness (low modulus of elasticity), high thermal coefficient of expansion, and low strength. Some of these drawbacks have been overcome through the use of metal matrix composites of these metals. Typically, ceramics are added to the metals. The primary objectives of these additives have been to inc...

AI Technical Summary

Benefits of technology

[0005] Accordingly, it is an object of the present invention to provide a metal matrix composite using molten metal of aluminum, magnesium and titanium wherein a minimum of stirring is required to maintain particles of the additive agent in suspension.

[0007] It is a further object of the present invention to provide a metal matrix composite wherein the additive particles increases the ductility of the metal matrix composite.

[0013] While a range of compositions of from about 0.1 wt. % to about 80 wt. % of calcium hexaboride can be utilized relative to the aluminum, a range of about 5 to about 40 wt. % is most practical for most applications and was utilized for testing. The calcium hexaboride typically has an average particle size range of about 0.1 to about 200 microns. The resultant metal matrix is light weight has improved strength, increased ductility and reduced thermal coefficient of expansion.

Problems solved by technology

These metals suffer from some drawbacks, however, which limit their usefulness.

These include low stiffness (low modulus of elasticity), high thermal coefficient of expansion, and low strength.

Similar problems would be observed with molten magnesium.

Furthermore, because of the contamination and the non-uniform nature of the metal matrix composites, remelting (for recycle, etc.) is a problem due to the variability of the resulting feed product.