Grain refinement and high thermal stability in laser surface remelted Mg-4Y-3Nd-1.5Al alloy

Abstract

Aluminum is a low-cost alloying element. Adding 1.5 Al (wt.%) to Mg-4Y-3Nd (Mg-RE) alloy leads to a significant grain refinement in the laser surface remelting (LSR) process. The in-situ precipitated Al2RE particles and interdendritic eutectic Al2RE phase formed during the previous solidification turn into a new class of nuclei, and refine the grain structure. The rapid solidification results in the formation of nanoscale Al-RE intermetallic compounds within alloy that ensure excellent thermal stability in grain structure with only 1.85% hardness loss after heat treatment at 545 °C for 30 h by Zener pinning mechanism.