Fabrication of Magnesium-Based Surface Composite Using Friction Stir Processing.

The increasing demand for lightweight, high-performance materials in the transportation sector has accelerated the development of advanced metal matrix composites. Carbon-based nanomaterials are widely utilized to improve the mechanical and microstructural properties of these materials. In the present study, a multi-walled carbon nanotube (MWCNT)-reinforced AZ31 magnesium alloy surface composite was fabricated through friction stir processing (FSP) using a variable revolutionary pitch (RP), while maintaining all other processing parameters constant. The fabricated composites exhibited a more uniform particle distribution and significant grain refinement, with the average grain size decreasing from 33 µm in the base material (BM) to 4.5 µm for 0.1 RP and 5.7 µm for 0.05 RP. Furthermore, the microhardness increased by nearly 72 %, while the tensile strength improved by up to 82% compared to the BM. These enhancements are primarily attributed to grain boundary strengthening and Zener pinning effects induced by dynamic recrystallization (DRX).