Improving the tribological properties of mg based AZ31 alloy using friction stir processing

Abstract

Materials with improved tribological properties have become the pre-requisite of advanced engineering design. Surface metal matrix composites (SMMCs) exhibit a unified combination of good tribological properties and high toughness of the interior bulk metal when compared with monolithic materials. Friction stir processing, a microstructure modification technique, has emerged as one of the processes used for fabrication of SMMCs. Commercial cast or wrought type Mg-Al- Zn AZ-series alloys, such as AZ91, AZ61 or AZ31 with 3-9 wt.% Al and 1 wt.% Zn, have been widely used in automobiles or electronic appliances. Due to low percentage of alloying elements/second phase elements in these alloys, the grain refinement and hence the mechanical properties such as hardness cannot be appreciably enhanced. In this study, FSP was used to fabricate AZ31 based nanocomposite using TiC as reinforcement. FSP was performed at a fixed volume fraction of TiC under varying cooling conditions. Tribological performance of the fabricated composite was investigated using pin-on-disc wear test arrangement. The analysis of the wear surfaces as well as wear debris analysis was done using SEM equipped with EDS. The fabricated composite was found to exhibit superior wear resistance.