Manufacture of alloys containing dispersed fine particulate material

Abstract

A method of preparing a metal alloy comprising a dispersion of particles of a first metallic material consisting of one or more refractory hard metals in a matrix of a second metallic material includes establishing a molten body of the second metallic material and introducing solid particles of the first metallic material into the molten body. Alternatively solid particles of a metalloid which reacts with the second metallic material to form particles of the first metallic material may be introduced into the molten body. The first metallic material has a higher melting point than the second metallic material and is substantially insoluble therein. The molten body is then stirred at a rate sufficient to effect shearing of the surfaces of the particles such that the surfaces are wetted by the molten body, and the molten body containing the resultant dispersion is cast in any desired manner.

Description

[0001] The present application is directed to a novel method of preparing metal alloys containing finely divided particulate metal or intermetallic compounds as a substantially insoluble second phase. A particular embodiment is directed to manufacture of aluminum base master alloys containing titanium together with boron or boron alone.BACKGROUND TO THE INVENTION[0002] Products containing dispersions of fine particulate non-metallic material in metals and alloys, commonly known as metal matrix composites, are well known in metallurgical engineering. Examples are dispersions of metal oxides, nitrides, carbides and the like in a matrix of aluminum or alloys thereof. Commercial use of such composites was delayed for many years by the need to develop consistent and reliable means of manufacture of sound defect-free components. Mass production of such components required melting and casting methods for conventional metal alloys to be adapted to metal matrix composites. This required comp...

AI Technical Summary

Problems solved by technology

Commercial use of such composites was delayed for many years by the need to develop consistent and reliable means of manufacture of sound defect-free components.

This required complete wetting of the particle surfaces by the molten matrix metal which, in the early stages of this technology, was difficult to achieve.

Moreover, any coarse particles or agglomerates may function as hard inclusions and impair the mechanical properties of the final product.

Such conductivity may be impaired by small quantities of the transition metals, titanium, chromium and vanadium commonly present in solution in commercial aluminum, rendering the product unsuitable for its intended use.

Firstly, use of the double fluorides of both titanium and boron entail severe environmental problems.

This requires elaborate emission control installations which are expensive to install and maintain and liable to malfunction.

These processes increase labour requirements.

Particle size control, particularly in AI--Ti--B master alloy production requires close control of temperature and time conditions, not always successfully achieved in an industrial environment.