Microstructure Stability and Creep Strength in a Die-Cast AX52 Magnesium Alloy

Abstract

Superior creep strength of a heat resistant AX52 magnesium alloy is ascribed to the grain boundary eutectic Al₂Ca phase covering the primary α-Mg grains. The eutectic phase is stable in morphology at temperatures below 473 K, while it collapses during long term exposure at temperatures higher than 473 K. The microstructural change of the alloy during high temperature exposure is characterized by the decrease in the grain boundary coverage by the eutectic phase. The creep strength of the alloy decreases with the decrease in the grain boundary coverage, and the correlation between the creep strength and the grain boundary coverage is discussed.