复合添加Zr、Cr和Pr对Al-Zn-Mg-Cu合金组织和性能的影响

Effects of Zr, Cr and Pr additions on microstructure and properties of Al-Zn-Mg-Cu alloys

采用铸锭冶金法制备Al-Zn-Mg-Cu-Zr、Al-Zn-Mg-Cu-Cr-Pr和Al-Zn-Mg-Cu-Zr-Cr-Pr3种合金,通过金相显微、扫描电镜和透射电镜观察以及拉伸性能、极化曲线、应力腐蚀和剥落性能的测试,研究复合添加Zr、Cr和Pr对Al-Zn-Mg-Cu合金组织和性能的影响。结果表明:复合添加Zr、Cr和Pr可有效抑制Al-Zn-Mg-Cu合金回复过程中亚晶的合并和长大,显著抑制再结晶,提高合金抗应力腐蚀和抗剥落腐蚀的性能;与单独添加Zr的合金相比,复合添加Zr、Cr和Pr的合金断裂韧性KⅠC从23.3MPa·m1/2提高到29.3MPa·m1/2,合金应力腐蚀开裂界限应力强度因子KⅠSCC由10.9MPa·m1/2提高到24.5MPa·m1/2,合金的抗拉强度、屈服强度及伸长率都略有提高。

Three kinds of alloys Al-Zr-Mg-Cu-Zr, Al-Zn-Mg-Cu-Cr-Pr and Al-Zn-Mg-Cu-Zr-Cr-Pr were prepared by cast metallurgy. The effects of Zr, Cr and Pr additions on the microstrueture and properties of Al-Zn-Mg-Cu alloys were investigated by optical microscopy, scanning electron microscopy, transmission electron microscopy, tensile test, polarization curve measurement, stress corrosion and exfoliation corrosion test. The results show that the combined additions of Zr, Cr and Pr to the Al-Zn-Mg-Cu alloys effectively retard the mergence and growth of the sub-grain during the recovery process, significantly inhibits the recrystallization of Al matrix, thus enhances the resistance to stress corrosion and exfoliation corrosion. Compared with the Al-Zn-Mg-Cu alloy added with Zr, the complex additions of Zr, Cr and Pr into the Al-Zn-Mg-Cu alloy remarkably increase the fracture toughness （K1c） from 23.3 MPa·m1/2 to 29.3 MPa.m1/2, and enhance the resistance to stress corrosion cracking （K1scc） from 10.9 MPa·m1/2 to 24.5 MPa·m1/2, yield strength and elongation of the alloys all increase a little.