Influence of microstructure and texture on mechanical properties of aluminium alloy 2124+ 5percent SiC particulate composites

摘要

A study of texture, microstructure, mechanicalproperties, and crack propagation mechanisms was carried outon aluminium alloy 2124 reinforced with 5 vol.-percent SiCparticles (3 #mu#m). Three fabrication techniques have beenused to produce the composites. Composite I was fabricated byblending followed by hot isostatic pressing. Composite II wasfabricated by mechanical alloying followed by hot isostaticpressing. Composite III was fabricated by agglomeration ofaluminium powder by mechanical alloying followed byblending with SiC and hot isostatic pressing. All threecomposites were hot rolled to nominally 12.5 mm thick plate.Similar textures were observed for all composites. A model ofthe observed texture is {001} <211>, {1 11}<211>, and {211}<111> for rolling, side, and transverse planes respectively.Composite I showed a homogeneous distribution of SiCparticles. Transmission electron micrographs of composite Ishowed good interface bonding, stacking faults present in SiCparticles, and segregation of aluminium, oxygen, copper andmagnesium to the interface. Composites II and III showed aninhomogeneous distribution of SiC particles. The elasticmodulus was slightly higher in the <211> direction than in the<111> direction. The fracture toughness of composite I washigher in the <211> crack direction whereas that for compositeII and composite III was higher in the (111> crack direction.Secondary crack propagation modes follow the crystallographicorientations of {100} and {111} planes.