(中国科学院 金属研究所，沈阳 110016)
摘 要: 利用扫描电子显微镜(SEM)和电子探针(EPMA)研究液态金属的冷却速率对Al-6Mg-0.2Sc-0.15Zr(质量分数，%)合金中初生相的结构、形貌及成分的影响。结果表明：在较低的冷却速率下(随炉冷却)，液态金属中析出的初生相为L12结构的Al3(Sc, Zr)相和D023结构的Al3(Zr, Sc)相。初生Al3(Sc, Zr)相为Zr溶解在Al3Sc相中的固溶体，具有复杂的形貌和较高的体积分数；当冷却速率较大时(钢模具冷却)，D023结构的Al3(Zr, Sc)相的析出受到抑制而形成L12结构的Al3(Sc, Zr)相或亚稳态的Al3(Zr, Sc)相；当冷却速率足够大时(铜模具冷却)，α(Al)基体在较高的过冷度下快速结晶，初生相的形成完全受到抑制。
关键字: 铝合金；Al-Mg-Sc-Zr合金；初生相；冷却速率；显微组织
（Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China）
Abstract:The effects of cooling rate on microstructures, morphology and composition of the primary precipitates in an Al-6Mg-0.2Sc-0.15Zr alloy were studied by SEM and EPMA. The results show that, at slower cooling rate (furnace cooling), the primary precipitates consist of L12 structured Al3(Sc, Zr) and D023 structured Al3(Zr, Sc) phases, which have complex shapes and higher volume fraction. At moderate cooling rate (iron mould), the D023 structured Al3(Zr, Sc) is suppressed while cubic and L12 structured Al3(Sc, Zr) or metastable Al3(Zr, Sc) form, which have lower volume fraction but higher number density. At rapid cooling rate (copper mould), the α(Al) quickly solidifies due to the large undercooling while the formation of precipitate is suppressed.
Key words: aluminium alloy; Al-Mg-Sc-Zr alloy; primary phase; cooling rate; microstructure
