Studies on the Fabrication of Surface Composites on Cast Aluminum Alloys using Friction Stir Processing - A Review

Aluminum and its alloys are used extensively in aerospace and automotive industries because of its low density and high strength to weight ratio. Metal matrix composites are a new class of materials that exhibit good wear and erosion resistance properties, higher stiffness and hardness at a lower density as compared to the matrix. However, the presence of the ceramic particles in the metallic matrix makes the matrix brittle Hence, instead of bulk reinforcement, if the ceramic particles would be added to the surface, it could improve the wear and erosion resistance without sacrificing the bulk properties. Dispersion of ceramic particles on metallic substrate surface and the control of its distribution are difficult to achieve by conventional surface treatments. Recently, much attention has been paid to a new surface modification technique named friction stir processing.FSP is a solid state processing technique to obtain a fine-grained microstructure. It is well known that the stirred zone consists of fine and equiaxed grains produced due to dynamic recrystallization. Though FSP has been basically advanced as a grain refinement technique, it is a very attractive process for also fabricating composites. This research aims at fabricating surface composites of SiC/Al2O3 (particulate) on cast aluminum alloys. It will enhance the wear resistance of Al alloy by dispersion of nano-sized particulates on the surface using FSP technique.