Effect of processing environment during friction stir processing of AZ31/ (ZrO2+CuO)p surface composite on the mechanical and tribological performance

In this work, the AZ31 Mg alloy was subjected to friction stir processing (FSP) by adding CuO and ZrO2 particles. The main aim of this study was to increase the tribological and mechanical behavior of AZ 31/(CuO + ZrO2)p surface composite in air and water. The influence of the processing media on the microstructural modification and mechanical properties of the developed composites is assessed via optical microscopy (OM), scanning electron microscopy (SEM), transmission electron microscopy (TEM), shear punch testing (SPT) and Vickers hardness testing. It had been found that finer grains are produced in the stir zone due to the reduction in heat input for the water-cooled composite relative to the air-cooled composite. Indeed, the water-cooling system acted as a hamper and suppressed grain growth, which consequently resulted in the enhancement of the mechanical and tribological behavior of the AZ 31/(CuO + ZrO2)p surface composite.