摘要
采用金属型铸造方法,制备了不同RE含量的Al-4.5Zn-1.0Mg-0.8Cu合金。利用力学性能测试、OM、SEM及EDS等分析测试手段,研究了RE对Al-4.5Zn-1.0Mg-0.8Cu合金微观组织和力学性能的影响。结果表明,随着RE加入量的增加,合金的抗拉强度和伸长率均呈先增大后减小的趋势。在试验范围内,加入0.12%的RE(质量分数)时,合金具有最优的综合力学性能。加入适量RE可明显减小合金二次枝晶间距。RE主要偏聚在晶界和枝晶界处,以AlZnMgCuRE相形式呈短棒状存在。加入过量RE会对合金产生过变质作用,增大合金二次枝晶间距,AlZnMgCuRE相呈粗大的块状,割裂作用增加,降低合金的力学性能。RE还促进了Mg和Zn在Al中的固溶,增强了固溶强化作用。
A1-4.5Zn-1.0Mg-0.8Cu alloys containing different RE content were prepared by metal mould casting. Effects of RE on microstructure and mechanical properties of A1-4. 5Zn-1. 0Mg-0. 8Cu alloy were investigated by tensile testing, OM（optical microscovpe）, SEM（scanning eldctron microscope） and EDS（energy dispersive spectrometer）. The results show that the tensile strength and elongation are in- creased firstly, and then decreased with the increase of RE content. The alloy with 0.12% RE（mass fraction） exhibits the desriable mechanical properties. With proper RE, secondary dendrite arm spacing can be decreased, and RE is distributes mainly at grain boundaries and dendrite boundaries in form of A1ZnMgCuRE phase. Excessive RE can cause over-modification effect, increasing secondary dendrite arm spacing. With a lower RE content, A1ZnMgCuRE phase exhibits rod-like shape, and with excessive RE, A1ZnMgCuRE phase becomes coarse block structure, which can weaken the mechanical properties as a result of cutting effects. In addition, RE can promote the solid solution of Mg and Zn in A1 melt, improving the solid solution strengthening effects.
出处
《特种铸造及有色合金》
CAS
CSCD
北大核心
2012年第12期1163-1167,共5页
Special Casting & Nonferrous Alloys
基金
福建省自然科学基金资助项目(2009J01245)
