(上海交通大學(xué) 金屬基復(fù)合材料國家重點(diǎn)實(shí)驗(yàn)室,
上海 200030)
摘 要: 用熱裂環(huán)法考察合金的熱裂傾向性， 并對合金的冷卻曲線和鑄態(tài)組織進(jìn)行了分析。 Zn加入Mg-9Al合金降低了合金的凝固結(jié)束溫度， 平均每增加0.1%， 合金的凝固結(jié)束溫度降低0.7℃。 Zn促進(jìn)了Mg17Al12相在晶界的析出，降低了凝固結(jié)束溫度， 并顯著增加了合金的熱裂傾向性。 RE對Mg-9Al合金的熱裂傾向性和凝固結(jié)束溫度影響很小。但當(dāng)Zn含量超過0.8%時(shí)， RE的加入可以顯著降低Mg-9Al-Zn合金的熱裂傾向性。
關(guān)鍵字: Mg-Al合金; Zn; RE; 熱裂; 凝固
DING Wen-jiang, ZHU Yan-ping
（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
