Effect of Aging Treatment on the Tensile Properties of Mg-Nd-Y-Zr-Zn Casting Alloys

Abstract

Magnesium alloys are alloyed with rare earth elements (Re, Ca, Sr) due to the limited use of magnesium in high-temperature conditions. In this study, the influences of Zr and Zn on the aging behavior of a Mg-Nd-Y alloy were investigated. magnesium alloys containing R.E elements require aging treatments Specifically, Nd, Y and Zr are commonly used for high-temperature magnesium alloys. Various aging treatments were conducted at temperatures of 200, 250 and <TEX>$300^{\circ}C$</TEX> for 0.5, 1, 3, 6, and 10 hours in order to examine the microstructural changes and mechanical properties at a high temperature (<TEX>$150^{\circ}C$</TEX>). Hardness and high-temperature (<TEX>$150^{\circ}C$</TEX>) tensile tests were carried out under various aging conditions in order to investigate the effects of an aging treatment on the mechanical properties of a Mg-3.05Nd-2.06Y-1.13Zr-0.34Zn alloy. The maximum hardness was 67Hv; this was achieved after aging at <TEX>$250^{\circ}C$</TEX> for 3 hours. The maximum tensile, yield strength and elongation at <TEX>$150^{\circ}C$</TEX> were 237MPa, 145MPa and 13.6%, respectively, at <TEX>$250^{\circ}C$</TEX> for 3 hours. The strengths of the Mg-3.05Nd-2.06Y-1.13Zr-0.34Zn alloy increased as the aging time increased to 3 hours at <TEX>$250^{\circ}C$</TEX> This is attributed to the precipitation of a Nd-rich phase, a Zr-rich phase and <TEX>$Mg_3Y_2Zn_3$</TEX>.