Effect of Heat Treatment on Microstructure of Al4Cu-SiC Composites Consolidated by Powder Metallurgy Technique

Abstract

AbstractSilicon carbide particles-reinforced Al4Cu composites containing 2.5, 5 and 7.5 wt.% of reinforcement were fabricated using powder metallurgy (PM) technique. The sintered Al4Cu-SiC composites were solution treated for 6 h at two different temperatures (495 and 530 °C) and then aged at 180 °C for various aging periods (4, 12 and 24 h). Effects of heat treatment on the microstructural changes and microhardness were investigated by scanning electron microscope, transmission electron microscope, x-ray diffraction and microhardness tests. The results indicate the ceramic particles-reinforced Al4Cu matrix requires different heat treatment parameters compared to the unreinforced alloy. The applied solution temperature did not allow for thorough dissolution of alloy phases in the matrix material produced by PM route. However, in Al4Cu-SiC composites the main strengthening phase (Al2Cu) was uniformly distributed in the matrix. The solid-solution temperature increase affects the reduction in time to reach peak hardness. The highest increment in microhardness by aging treatment was observed for composite with the addition of 5 wt.% of SiC solution treated at 530 °C for 12 h (110 HV0.05).