微量钪对Al-Zn-Mg-Cu-Zr铝合金组织与性能的影响

采用铸锭冶金法制备了Al 7.6Zn 2 .2Mg 1.2 4Cu 0 .13Zr和Al 7.8Zn 2 .2Mg 1.3 0Cu 0 .3 0Sc 0 .14Zr合金 ,测试了不同热处理状态下合金的力学性能和电导率 ,利用金相显微镜和透射电子显微镜研究了 2种合金不同处理态的显微组织 ,利用扫描电镜观察铝合金的拉伸断口。结果表明 :添加微量的Sc可以明显细化合金的铸态晶粒 ,显著提高Al Zn Mg Cu Zr合金的力学性能和电导率 ,其作用机理主要为Al3 (Sc ,Zr)引起的细晶强化、亚结构强化和弥散强化。

Effect of Trace Sc on Microstructures and Properties of Al-Zn-Mg-Cu-Zr Based Alloys

Two kinds of Al-Zn-Mg-Cu-Zr based alloys with and without Sc were produced by ingot-metallurgy processing. The tensile mechanical properties and electric conductivity of the two alloys under different treatment conditions were tested and the microstructures of the alloys were studied by using optical microscope and transmission electron microscope(TEM). The fracture surface of the tensile test specimens of the alloys were investigated by scanning electron microscope(SEM). The results show that adding trace Sc can greatly fine the grain size of the Al-Zn-Mg-Cu-Zr alloy ingots and obviously improve the tensile properties and electric conductivity of the Al-Zn-Mg-Cu-Zr alloys. The strengthening mechanism are considered as fine grain strengthening, substructure strengthening and dispersion strengthening by Al 3(Sc,Zr).