Fabrication of Magnesium–NiTi_p Composites via Friction Stir Processing: Effect of Tool Profile

Abstract

In this study, a solid-state fabrication route via friction stir processing (FSP) was used to fabricate Nitinol particulate (NiTip)-reinforced magnesium-based composites to avoid the diffusion reaction and the formation of brittle interfacial compounds. The effect of four tool profiles on the homogeneity in the dispersion of NiTip particles in the magnesium matrix and microhardness was examined and analyzed. A counter-clockwise scrolled shoulder with a plain cylindrical pin and three tools with a flat shoulder having plain cylindrical pin, left-hand, and right-hand threaded pins were used and compared. The tool profiles were observed to exhibit a significant influence on the microstructure of the fabricated Mg/NiTip composites. A wider and more uniform distribution of NiTip particles along with superior bonding with magnesium matrix was achieved with a left-hand threaded cylindrical pin tool. The incorporation of NiTip gave rise to a significant increase in the microhardness of the fabricated composites due to a variety of strengthening mechanisms.

Keywords

• magnesium
• shape memory alloy
• composite
• friction stir processing
• tool profile
• microstructure