微量Zr、Er对Al-Zn-Mg合金组织与性能的影响

Effects of Trace Zr and Er on Microstructure and Properties of Al-Zn-Mg Alloys

采用硬度、拉伸性能、电阻率和抗应力腐蚀性能测试及金相组织观察等方法,研究了微量Zr、Er对Al-4.4Zn-2.4Mg(质量分数,下同)合金组织与性能的影响。结果表明,单独添加Zr的细晶作用优于单独添加Er以及Er、Zr复合添加,Er、Zr复合添加能显著抑制合金的再结晶行为,Er、Zr复合添加后合金的力学性能和单独添加微量Zr的基本相当,但Er、Zr复合添加后合金抗应力腐蚀性能优于单独添加微量Er、Zr,Er、Zr复合添加的Al-Zn-Mg合金综合性能最好。Er、Zr复合添加提高应力腐蚀抗力是通过抑制再结晶获得纤维组织间接实现的。

Effects of trace Zr and Er additions on microstructures and mechanical properties of Al-4.4Zn-2.4Mg alloys （mass fraction, similarly hereinafter） were investigated by testing hardness, tensile property, resistivity, and stress corrosion cracking resistance and observing metallographic microstructure of the alloy. The results show that the grain refining effect of Zr addition alone for the alloy is better than that of Er addition alone or Zr-Er co-addition. However the Zr-Er co-addition can obviously inhibit recrystallization behavior of the alloys. The Al-4.4Zn-2.4Mg alloy with Zr-Er co-addition has nearly equal mechanical properties to that with Zr addition alone, while has better stress-corrosion cracking resistance than that with Zr or Er addition alone. The alloys with Zr-Er co-addition possess the optimum combination properties. Zr-Er co-addition can improve the stress-corrosion cracking resistance of the Al-4.4Zn-2.4Mg alloy, which is indirectly realized by the fibrous microstructure obtained from inhibiting recrystallization.