Microstructural and mechanical behaviour of spray formed Al-Si-Gr composites synthesised by friction stir processing

Abstract

In this study, Al-Si-Gr composites for cylinder liner application were synthesised using a spray forming technique, aiming
at improving the wear resistance. Silicon (Si) and graphite (Gr) particles, which do not distribute uniformly in the aluminium
matrix by conventional processes, are dispersed uniformly throughout the composite using spray forming. Al–6Si-5Gr, Al-
12Si-5Gr, and Al–18Si-5Gr composites were used to make disc-shaped spray form castings, and then their microstructures
were studied. In spray form castings, it was found that the Si and Gr particles were distributed homogeneously in the Al-
matrix. Friction stir processing (FSP) was performed on spray formed Al-Si-Gr composites. In the present work, FSP was
introduced to refine the microstructure of spray formed Al-Si-Gr composites. The microstructure of the stir zone (SZ) was
observed to be highly refined compared to the spray forming material. FSP resulted in the elimination of casting defects,
especially porosity and complete homogenisation. Other than this FSPed sample showed higher hardness compared to
spray formed sample.