Influence of Tool Rotational Speed on the Formation of Friction Stir Processing Zone in Cast Zk60/SiCp Magnesium Alloy Surface Composites

Abstract A Cast ZK60 magnesium alloy plays a tremendous role in the fabrication of lightweight structural materials. However, the low surface properties, like low friction and wear resistance, restricts the magnesium alloy during the structural application. Conventionally, the surface properties of magnesium alloys were improved using various processing methods like high-energy electron beam irradiation, plasma-transferred arc surfacing, and high-energy laser melt treatment. However, the above processes are involved in melting the magnesium material, which results in defects and detrimental metallurgical phase formation. Friction Stir Processing (FSP) can overcome this problem since the processing is done in the solid state. However, FSP often appears to be a significant applicant on the magnesium plate to attain successful fabrication of surface metal matrix composites. In this investigation, an attempt at FSP zone formation in magnesium alloy has been made in order to understand the influences of rotational speeds ranging from 700 to 1,100 r/min. From this investigation, it is found that the FSP made by using the high tool rotational speed of 900 r/min and 10 mm/min exhibited higher hardness and uniform particle distribution. This may be attributed to the grain boundary and dispersion strengthening.