Microstructural characterization and properties of aluminium 7075/Mo prepared by microwave sintering for high-strength application

Ceramic particulates are often used in reinforcement of aluminium alloys. The use of this particulates results in embrittlement and lowering of ductility. In tackling this, the present study involved the use of relatively ductile metal particles (molybdenum) as reinforcement. Molybdenum (Mo) powder was blended with Al-7075 powder at 4, 8 and 12 wt. %, compacted at 25 MPa, and microwave sintering was performed at 350, 450 and 550 °C. The effect of the variation in Mo dosage and sintering temperature on the phases, microstructure and properties was evaluated. The result showed varying phases and microstructural evolution in the composites. For all proportion of the Mo particles, 350 and 450 °C favoured porosity and sintered and relative densities, whereas 550 °C was detrimental to the properties. It was observed that 4 and 8 % Mo enhanced microhardness and tensile strength, while 12 % Mo showed a decrease in hardness and a strength. In the same way, sintering temperatures of 350 and 450 °C aided improvement in hardness and tensile strength, even as 550 °C exhibited lower property values. It was concluded that proportions of molybdenum not greater than 8 wt. % and sintering temperature not greater than 450 °C are suitable for property improvement.