Investigation of Mechanical Property and Microstructure of Nanocomposite AZ۳۱/SiC Fabricated by Friction Stir Process

The friction stir process (FSP) is a solid state process, which has been used to insert reinforcing particles into the structure of a material to create a composite with improved properties. Magnesium is a light structural metal that is increasingly used in the aerospace and automobile industries. In this research, SiC nanoparticles were added to AZ۳۱ alloy using FSP in two overlaps of ۱۰۰% and ۵۰% passes. In ۱۰۰% pass overlapping, nanoparticles were added in ۴, ۸ and ۱۶ volume percentages and in ۵۰% pass overlapping only nanoparticles in ۴ volume percent were added. The FSP process performed as ۴ consecutive passes in both overlaps along with rapid cooling. Microstructure, hardness and tensile strength of created composites were examined. The results suggested that adding reinforcing materials causes reduction in the size of the grains, uniformity of structure and increase in the hardness of material. SiC nanoparticles distributed uniformly through the AZ۳۱ alloy. By increasing volume fraction of reinforcing materials, yield stress of the material increased but ultimate stress and formability properties reduced. In ۵۰% overlapping state, the yield stress in directions, either parallel or perpendicular to the pin direction, increased rather than ۱۰۰% overlapping state, but the ultimate stress and elongation properties reduced. This reduction was greater in the perpendicular direction relative to the pin direction.

Keywords:

Friction stir process , Magnesium AZ۳۱ , Mechanical strength , SiC nanoparticles