Effect of Hybrid Length Scales (Micro + Nano) of SiC Reinforcement on the Properties of Magnesium

In this study, pure magnesium reinforced with micron, nano and micron + nano-size SiC particulates was synthesized using powder metallurgy technique coupled with a novel microwave assisted rapid sintering. The sintered billets were subsequently extruded and characterization studies were performed on the extruded specimens to assess the microstructural, physical and mechanical properties of the composites. Microstructural characterization revealed good interfacial integrity between the matrix and reinforcements. Results of thermal mechanical analysis indicate most significant decrease in the coefficient of thermal expansion of the magnesium matrix with the use of hybrid reinforcements. Mechanical characterization revealed that composite samples exhibited an increase in microhardness of the matrix and strength over that of pure magnesium while ductility was adversely affected. An attempt is made to correlate the effect of single length scale and mixed length scales of SiC reinforcement on the properties exhibited by pure magnesium.