Aluminium-lithium/SiCp composites produced by mechanically milled powders

Abstract

Aluminium-lithium/SiCp composites have attracted special interest because of their low density and high modulus. However, the major problem is the difficulty in securing uniform mixing of the AlLi matrix powders and the SiC particles. Conventional mixing cannot prevent the reinforcements from agglomerating at prior particle boundaries. This paper reports the application of a mechanical milling method for mixing AlLi powders with SiC particles. The SiC particulates as reinforcements are dispersed homogeneously in this method. AlLi/SiCp composite powders mechanically milled at the high speed of 500 rpm are extruded at 773 K. The microstructure and mechanical properties are discussed. The optimal milling time for AlLi/10vf%SiCp is 2 h; the resulting Young's modulus being 86 GPa. The microstructures are studied by transmission electron microscope. The composites appeared to have good interfaces and fine grain structures.