L.B. Tong

Effect of Ce/La microalloying on microstructural evolution of Mg-Zn-Ca alloy during solution treatment

Abstract The effect of Ce/La misch metal addition on the microstructural evolution of as-cast and as-soluted Mg-5.3Zn-0.5Ca (wt.%) alloys was systematically investigated. It was found that Ce/La could effectively refine the as-cast alloy and restrain grain growth during solution treatment, which was derived from the constitutional supercooling during solidification process and the formation of stable intermetallic compounds CeMg 12 and Mg 17 La 2 . Furthermore, Ce/La microalloying and solution treatment resulted in an evolution from the original lamellar Ca 2 Mg 6 Zn 3 /α-Mg to the divorced eutectic structure. The thermal stability of Mg-Zn-Ca alloy could be effectively improved by Ce/La addition, because the low-melting-point binary Mg-Zn phase was transformed to Mg x Zn y -Ca-(Ce/La) phase with higher thermal stability and the amount of Ca 2 Mg 6 Zn 3 /α-Mg eutectic structure was reduced.