(中國科學(xué)院 金屬研究所，沈陽 110016)
摘 要: 利用掃描電子顯微鏡(SEM)和電子探針(EPMA)研究液態(tài)金屬的冷卻速率對Al-6Mg-0.2Sc-0.15Zr(質(zhì)量分?jǐn)?shù)，%)合金中初生相的結(jié)構(gòu)、形貌及成分的影響。結(jié)果表明：在較低的冷卻速率下(隨爐冷卻)，液態(tài)金屬中析出的初生相為L12結(jié)構(gòu)的Al3(Sc, Zr)相和D023結(jié)構(gòu)的Al3(Zr, Sc)相。初生Al3(Sc, Zr)相為Zr溶解在Al3Sc相中的固溶體，具有復(fù)雜的形貌和較高的體積分?jǐn)?shù)；當(dāng)冷卻速率較大時(鋼模具冷卻)，D023結(jié)構(gòu)的Al3(Zr, Sc)相的析出受到抑制而形成L12結(jié)構(gòu)的Al3(Sc, Zr)相或亞穩(wěn)態(tài)的Al3(Zr, Sc)相；當(dāng)冷卻速率足夠大時(銅模具冷卻)，α(Al)基體在較高的過冷度下快速結(jié)晶，初生相的形成完全受到抑制。
關(guān)鍵字: 鋁合金；Al-Mg-Sc-Zr合金；初生相；冷卻速率；顯微組織
（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
