Fabrication and Characterization of Functionally Graded Composites Using Friction Stir Processing

Functionally graded materials (FGM) are the composite materials that are heterogeneous wherein the compositions or microstructures vary locally resulting in certain variation in the local material properties. Moreover, certain challenges exist in their manufacturing techniques. In this study, functionally graded composites were manufactured by integrating SiC particles of particle size: 20–30 μm in a groove on aluminium alloy 6082-T6 plate using friction stir processing (FSP) route. Three sets of samples with variation in a volume percentage of SiC along the thickness were processed by one to three passes. The effect of multipass on microstructure, microhardness and wear behaviour of graded materials has been analszed. The functionally graded composite layer produced with three FSP passes has shown the superior wear resistance of 0.25 mm³/m; that is, because of its greater microhardness value of 110 HV which is 1.8 times greater than the base metal. The modifications were mainly because of microstructural alterations through FSP, better particle dispersion, decreased particle clustering and fine grain size (6.39 μm).