Processing and properties of SiC particulate reinforced Al-6.2Zn-2.5Mg-1.7Cu alloy (7010) matrix composites prepared by mechanical alloying

SIC particulate reinforced aluminium alloy (7010) matrix composites have been processed by mechanical alloying route starting from elemental powders. Proper post-consolidation by hot pressing or hot extrusion results in a fully dense composite compact that retains the fine microstructure developed during mechanical alloying. Addition of SIC was found to result in lower strengths at room temperature but higher strength at temperatures above 200 degrees C. There was nearly a 64% increase in the yield strength at 350 degrees C, brought about by addition of 20 wt.% SiC. The beneficial effects of SiC additions on mechanical strength are best realized at elevated temperatures. Fine precipitates of various intermetallics (CuAl2, Mg2Zn11, etc.) are found to be present in the solutionised and aged samples in addition to fine dispersoids of Al2O3, MgAl2O4, etc. inherited from the as-milled powders and/or formed during subsequent degassing and consolidation.