【摘要】 钪是铝合金中常见的添加元素,但关于钪在铝合金中的作用机制研究还不够深入。通过电阻炉熔炼方法制备了传统7N01铝合金与新型含钪7N01铝合金,经均匀化处理后将合金热挤压成板材并进行双级人工时效处理。采用电子背散射衍射（EBSD）和透射电镜（TEM）对比分析了传统7N01铝合金与新型含钪7N01铝合金的微观组织,对时效态热挤压板材力学性能进行了表征,并分析了合金强化的作用机制。结果表明:经470℃/24 h均匀化处理后,传统7N01铝合金中析出了少量的纳米Al₃（Zr,Ti）相,而含钪7N01铝合金中析出了大量纳米Al₃（Sc,Zr,Ti）相。这种高密度、与基体保持共格的Al₃（Sc,Zr,Ti）相对晶界迁移的钉扎效果显著,明显提升了再结晶形核的临界亚晶尺寸,抑制了热挤压过程中的动态再结晶,使含钪7N01铝合金几乎由完全的纤维结构组成。同时,含钪7N01铝合金的抗拉强度和屈服强度分别较传统7N01铝合金提高了10. 7%和13. 3%。计算结果表明,添加钪引起7N01铝合金的细晶强化和弥散强化效果分别为7和57 MPa,强化效果主要来源于Al₃（Sc,Zr,Ti）相的弥散强化。更多还原

【Abstract】 Sc is a common additive element in aluminum alloys,while the functional mechanism of Sc in aluminum alloys is not completely understood. The traditional 7 N01 aluminum alloy and novel Sc modified 7 N01 aluminum alloy were prepared by electrical resistance furnace melting. After homogenization treatment,two kinds of 7 N01 alloys were hot extruded into plates,then exposed to two-stage artificial aging. Microstructures were comparatively analyzed by electron backscatter diffraction（ EBSD） and transmission electron microscopy（ TEM）. The mechanical properties of aged hot-extruded plates were measured by electronic universal testing machine. Meanwhile,the functional mechanism to strengthen the alloy was analyzed. The results show that a small number of nanometer-sized _Zr,Ti phases are precipitated in traditional 7 N01 aluminum alloy,while a large amount of nanometer-sized Al₃（ Sc,Zr,Ti） phases exist in 7 N01 aluminum alloy with 0. 12 wt% Sc after homogenization treatment at 470 ℃ for 24 h. The high-density Al₃（ Sc,Zr,Ti） phases which are coherent with matrix have a significant pinning effect on the migration of grain boundaries. It obviously improves the critical subgrain size for recrystallization nucleating.Also,the dynamic recrystallization in the hot extruding process is effectively inhibited. As a result,7 N01 aluminum alloy with0. 12 wt% Sc is almost constitutive of full fiber-like structure. At the same time,the tensile strength and yield strength of 7 N01 aluminum alloy with 0. 12 wt% Sc are 10. 7% and 13. 3% higher than those of traditional 7 N01 aluminum alloy. The calculated results indicate that fine-grain strengthening and dispersion strengthening caused by Sc addition are 7 and 57 MPa,respectively. The strengthening effect is mainly derived from dispersion strengthening of Al₃（ Sc,Zr,Ti） phases.更多还原