Formation of solidification microstructures in centrifugal cast functionally graded aluminium composites

摘要

A large number of engineering components and structures demand location specific performance under service conditions. A gradual transition in the microstructure or composition can motivate the changes in the functions of the specific locations for meeting the requirements and these tailored materials are termed as functionally graded materials (FGM). Centrifugal casting has emerged as the simplest and cost effective technique for producing large size engineering components of functionally graded metal matrix composites. The present paper describes the formation of different types of gradient solidification microstructures in SiC, B₄C, SiC-graphite hybrid, primary silicon, Mg₂Si and Al₃Ni reinforced functionally graded aluminium composites processed by centrifugal casting and correlate the microstructures with materials and processing parameters. The densities and size of the reinforcements play a major role in the formation of graded microstructures, the high density particles/phases both SiC and Al₃Ni form gradation towards the outer periphery and low density particles like graphite, primary silicon and Mg₂Si form gradation towards inner periphery. The B₄C particle having closer density to Al alloy has given more scattered distribution compare to other systems. However, functionally graded composite containing the SiC and Graphite particles has shown gradation towards inner periphery.