Synthesis and characterization of free standing, bulk Al/SiCp functionally gradient materials: effects of different stirrer geometries

This study addresses the effects of different stirrer geometries (two bladed, four bladed and circular shaped) on the synthesis of Al/SiCp functionally gradient materials (FGMs) by an innovative process, termed here as the gradient slurry disintegration and deposition process. The results of the three FGMs synthesized, revealed in common, an increase in the weight percentage of SiCp, porosity and microhardness along the direction of deposition. Thermomechanical analysis of the FGMs showed that the average coefficient of thermal expansion of the high SiCp end was reduced, as compared to that of the low SiCp end. Of the three stirrer geometries used, the two bladed stirrer yielded the most satisfactory results. An attempt is made in this study to establish the relationship between the processing parameter such as stirrer geometries, with the gradient of SiC particulates realized in the ingots, microstructural evolution, CTE and microhardness results obtained.