Effect of sintering temperature and heating mode on consolidation of Al-7Zn-2•5Mg-1Cu aluminum alloy

Densification behaviour, phase transformation, microstructural evolution and hardness values of microwave sintered Al-7Zn-2 center dot 5Mg-1Cu (7775) aluminum alloy were investigated and compared with conventionally sintered samples. Microwave sintering was performed in 2 center dot 45 GHz multimode microwave furnace at temperatures ranging from 570-630 A degrees C. Microwave sintering at a heating rate of as high as 22A degrees C/min resulted in similar to 55% reduction of processing time as compared to conventional sintering. A lower sintered density observed in the case of microwave processed samples was attributed to the inhomogeneity in microstructure and phase distribution. The X-ray diffraction results of conventionally sintered samples showed the presence of MgZn2, Mg2Zn11 and CuMgAl2, while only MgZn2 and CuMgAl2 phases were found in the case of microwave sintered samples and in lesser amount. Higher hardness and high standard deviation values were noticed for microwave sintered samples as compared to conventional counterparts.