Regarding the effect of aging heat treatment on the failure behaviour of a SiC reinforced Al based metal matrix composite

Abstract

In the present study, 6061 Al metallic matrix was reinforced by 12.2 wt % of SiC particulates using liquid metallurgy route. The composite material thus obtained was extruded and characterized in the assolutionized and peak aged conditions in order to delineate the effect of aging associated precipitation of secondary phases on the tensile fracture behavior of the composite samples. The results of microstructural characterization studies carried out using scanning electron microscope revealed the increased presence of precipitated secondary phases in the metallic matrix and a more pronounced interfacial segregation of alloying elements in case of peak aged samples when compared to the assolutionized samples. The results of the fractographic studies conducted on the as-solurionized samples revealed that the failure was dominated by the SiC particulates cracking while for the peak aged samples the fracture surface revealed a comparatively more pronounced SiC/6061 Al debonding and reduced SiC particulates cracking. This change in the failure behavior was rationalized in terms of embrittlement of the interfacial region brought about by the aging heat treatment and is correlated, in addition, with the mechanical properties of the composite samples in as-solutionized and peak aged conditions.