Effect of microwave and conventional heating on sintering behavior and properties of Al-Mg-Si-Cu alloy

Effect of heating mode and sintering temperature on sinterability and properties of the 6711 (Al-1Mg-0.8Si-0.25Cu) alloy was investigated. Alloy compacts were consolidated in conventional and microwave furnace at 570, 590, 610 and 630 degrees C under vacuum (10(-6) torr). Microwaves coupled with the compacts and resulted in 58% reduction in processing time along with higher heating rates when compared to conventional sintering. However rapid heating rate resulted in inhomogeneous microstructure with larger melt fraction at grain boundaries. XRD analysis showed absence of intermetallics due to insufficient time for diffusion. With increasing sintering temperature, all compacts did undergo supersolidus liquid phase sintering (SLPS), accordingly higher densification and shrinkage was observed. The electrical conductivity and hardness followed similar trend as sintered density in both modes. Alloy compact sintered at 630 C resulted in significant improvement of mechanical properties (TRS: 57%up arrow; UTS: 27%up arrow and ductility: 41%up arrow) in conventional mode. Age hardening treatment under T6 temper enhanced the tensile strength by 136% with drastic reduction in ductility as compared with sintered compacts. (C) 2011 Elsevier B.V. All rights reserved.