【摘要】 研究了微量 Ｓｃ对 Ａｌ－Ｍｇ合金显微组织与拉伸性能的影响．结果表明，微量Ｓｃ在 Ａｌ－Ｍｇ合金中主要以初生 Ａｌ３Ｓｃ和次生 Ａｌ３Ｓｃ两种形式存在．初生 Ａｌ３Ｓｃ是合金在凝固过程中形成的，可成为有效的非均质晶核，大大细化合金的铸态晶粒．次生 Ａｌ３Ｓｃ是合金铸锭在工艺加热过程中析出的，有效地钉扎位错和亚晶界， 稳定亚结构并强烈抑制合金的再结晶，具有亚结构强化和直接析出强化作用．因此，加入 Ｓｃ后的 Ａｌ－Ｍｇ合金的强度大大提高，并且表现出良好的强塑性配合．更多还原

【Abstract】 The effects of minor addition of Sc on microstructure and tensile property of Al-Mg alloy have been investigated. The results show that minor Sc mainly exists in the form of primary Al3Sc and secondary Al3Sc. Sc addition can produce a substantial refinement of the grain size of aluminium alloy castings due to the formation of the primary Al3Sc intermetallic phase during solidification. Secondary Al3Sc dispersoids precipitating from the supersaturated a(Al) solid solution in the heating process of ingot can effectively pin dislocation and subgrain boundary, stabilize substructure as well as inhibit the recrystallization of Sc containing Al-Mg alloy during hot rolling and annealing. The addition of Sc significantly increases the strength of the alloy and makes alloy get a superior combination of strength and ductility.更多还原