(上海交通大学 金属基复合材料国家重点实验室,
上海 200030)
摘 要: 用热裂环法考察合金的热裂倾向性， 并对合金的冷却曲线和铸态组织进行了分析。 Zn加入Mg-9Al合金降低了合金的凝固结束温度， 平均每增加0.1%， 合金的凝固结束温度降低0.7℃。 Zn促进了Mg17Al12相在晶界的析出，降低了凝固结束温度， 并显著增加了合金的热裂倾向性。 RE对Mg-9Al合金的热裂倾向性和凝固结束温度影响很小。但当Zn含量超过0.8%时， RE的加入可以显著降低Mg-9Al-Zn合金的热裂倾向性。
关键字: Mg-Al合金; Zn; RE; 热裂; 凝固
（State Key Laboratory of Metal Matrix Composites,
Shanghai Jiaotong University,Shanghai 200030, China）
Abstract:Mg-9Al alloy was adopted as master alloy. Zinc and rare earth (RE) were added to the maximum quantity of1.2% and 1.6%, respectively. Their effects on the hot tearing susceptibility were investigated using crack-ring molds. Cooling curves and as-cast structure were analyzed. Zn additions descend the end-solidifying temperature of Mg-9Al alloy (about 0.7℃ per 0.1% Zn addition in average). In Mg-9Al alloy, Zn promotes the precipitation of Mg17Al12 in grain boundaries and increases the hot-tearing susceptibility coefficient (HSC) distinctly. RE additions have little effect on the HSC and the end-solidifying temperature of Mg-9Al, while they can descend the HSC of Mg-9Al-Zn alloys notably when the content of zinc is excess of 0.8%.
Key words: Mg-Al alloys; Zinc; RE; hot cracking; solidification
