【摘要】 采用铸锭冶金法制备Al-Zn-Mg-Cu-Zr-Ti和Al-Zn-Mg-Cu-Zr-Ti-Cr合金。通过金相显微镜、扫描电镜和透射电镜观察和硬度、力学、腐蚀性能测试,对比复合添加Zr和Ti的合金及复合添加Zr,Ti和Cr对Al-Zn-Mg-Cu合金组织和性能的影响。研究结果表明:在Al-Zn-Mg-Cu合金中复合添加Zr,Ti和Cr形成的大量10²0 nm共格的固溶部分Zn,Mg和Cu的（Al,Cr）₃（Zr,Ti）弥散相,这些弥散相强烈钉扎位错和亚晶界;与复合添加Zr和Ti相比,复合添加Zr,Ti和Cr能够显著细化Al-Zn-Mg-Cu合金铸锭组织,抑制基体再结晶;在提高合金强度、塑性和断裂韧性的同时,提高合金的应力腐蚀和剥落腐蚀抗力,合金应力腐蚀临界应力强度因子KISCC由5.0 MPa·m^1/2提高到12.6 MPa·m^1/2,剥落腐蚀由EC提高至EB-。更多还原

【Abstract】 Al-Zn-Mg-Cu-Zr-Ti and Al-Zn-Mg-Cu-Zr-Ti-Cr alloys were prepared by cast metallurgy. The effects of Zr, Ti and Cr additions on the microstructure and properties of Al-Zn-Mg-Cu alloy were compared to those of Zr and Ti additions by optical microscopy, scanning electron microscopy, transmission electron microscopy, hardness, tensile test and corrosion resistance measurement. The results show that the combined additions of Zr, Ti and Cr to Al-Zn-Mg-Cu alloys lead to the formation of L1₂-structured Zn, Mg, Cu-containing（Al,Cr）₃（Zr,Ti）. These 10-20 nm dispersoids remarkably pin the dislocations and subgrain boundaries. Compared to the combined additions of Zr and Ti, the combined additions of Zr, Ti and Cr to Al-Zn-Mg-Cu alloys have stronger grain refinement and recrystallization inhibition effect. Moreover, combined additions of Zr, Ti and Cr can enhance the resistance to stress corrosion cracking and exfoliation corrosion with the improved strength, fracture toughness and ductility. The critical stress intensity（KISCC） is enhanced from 5.0 MPa·m^1/2 to 12.6 MPa·m^1/2and exfoliation corrosion from EC to EB-.更多还原