Effect of whisker alignment on microstructure, mechanical and thermal properties of Mg-SiCw/Cu composite fabricated by a combination of casting and severe plastic deformation (SPD)

Abstract

In this research, microstructure evaluation, mechanical properties and thermal conductivity of the Mg-SiCw/Cu composite with laminar structure were investigated. For this purpose, SiC whiskers were added to magnesium alloy by using stir-casting, then the Mg-SiCw composite was bonded to copper layers by warm accumulative roll bonding (ARB). Based on the results of optical microscopy (OM) and scanning electron microscopy (SEM), SiC whiskers were well distributed in the magnesium matrix and they were aligned parallelly when the composites were plastically deformed at higher rolling passes. Furthermore, all layers remained continuous with localized necking sites. Also, no intermetallic compounds and phases were detected by XRD and EDS analyzes. Apart from the significant effect of severe plastic deformation on mechanical properties, the findings of mechanical tests point to the usefulness of reinforcements in improving up to 60% microhardness, Young's modulus, yield, and up to 41% tensile strengths. Further, thermal conductivities of composites increased by adding reinforcement and above all by increasing the number of rolling passes. This growth is attributed to the higher thermal diffusivity of copper and whiskers as well as the increased number of conductive layers within composite.

Keywords

• SiC whisker
• Warm accumulative roll bonding
• Stir-casting
• Thermal conductivity