(1. 中南大学 材料科学与工程学院,长沙 410083;
2. 中南大学 有色金属材料科学与工程教育部重点实验室,长沙 410083)
摘 要: 在迄今为止的所有微合金化元素中,钪可最大程度提高铝合金综合性能。相比传统铝镁合金,新型Al-Mg-Sc-Zr合金抗拉强度提高60~130 MPa,屈服强度提高80~150 MPa,且可获得大于2000%高速超塑性。与传统铝锌镁合金相比,新型Al-Zn-Mg-Sc-Zr合金抗拉强度提高66~96 MPa,屈服强度提高36~98 MPa,钨极氩弧焊系数大于0.75,搅拌摩擦焊系数大于0.90,且可获得大于1500%高速超塑性。钪锆添加到铝合金中可形成Al3(Sc,Zr)粒子,该粒子可细化铸造组织、抑制再结晶发生和稳定细晶组织,产生显著的细晶强化、亚结构强化和析出强化,从而提高合金强度,实现优良的超塑性能。
关键字: 铝合金;Al-Mg-Sc-Zr合金;Al-Zn-Mg-Sc-Zr合金; 微合金化;强化机制;超塑性
(1. School of Materials Science and Engineering, Central South University, Changsha 410083, China;
2. Key Laboratory of Nonferrous Materials Science and Engineering, Ministry of Education,
Central South University, Changsha 410083, China)
Abstract:In all micro-alloying elements, scandium offers the greatest potential for improving the property of aluminum alloys. Sc and Zr can improve the tensile strength and yield strength by 60-130 MPa and 80-150 MPa, respectively. The new Al-Mg-Sc-Zr alloy exhibits high strain rate superplasticity with the elongation more than 2000%. Compared with the tensile strength and yield strength of conventional Al-Zn-Mg, the corresponding values are 66-96 MPa and 36-98 MPa higher, respectively. Moreover, the welding coefficients of tungsten inert gas and friction stir welded joints are 0.75 and 0.90, which are higher in the new Al-Zn-Mg-Sc-Zr alloy, respectively. Furthermore, excellent high-strain superplasticity with the elongation above 1500% can be obtained in the new Al-Zn-Mg-Sc-Zr alloy. The Al3(Sc, Zr) particles can refine casting structure, inhibit recrystallization and the stabilize fine grain structure, and thus cause significant grain refinement strengthening, substructure strengthening and precipitation strengthening, which leads to the improvement of strength and excellent superplasticity.
Key words: aluminum alloy; Al-Mg-Sc-Zr alloy; Al-Zn-Mg-Sc-Zr alloy; micro-alloying; strengthening mechanism; superplasticity