超高强铝合金Al-7.88Zn-2.05Mg-1.70Cu-0.19Er薄带的组织与性能

Microstructure and Mechanical Properties of Ultra-high Strength Al-7.88Zn-2.05Mg-1.70Cu-0.19Er Aluminum Alloy Thin Strip

摘要:

研究了Al-7.88Zn-2.05Mg-1.70Cu-0.19Er合金薄带的组织、力学性能和耐腐蚀性能。结果表明，对厚度为0.5 mm的冷轧态薄带试样进行475 ℃/1 h/水冷固溶处理及120 ℃/6 h+150 ℃/24 h双级时效处理后，薄带合金具有优良综合性能，其硬度、极限抗拉伸强度、屈服强度和伸长率分别为1859.1 MPa、669.4 MPa、624.1 MPa和11.2%，该力学性能与峰值时效态合金的力学性能相当。该状态下合金的电导率、剥落腐蚀等级和应力腐蚀敏感指数分别为35.5%IACS、EA和4.07%。细小的球状Al₃(Er，Zr)和η?相均匀分布在Al基体中，且大部分析出物与Al基体晶格共格。细小不连续分布的晶界析出η相是该合金具有较低应力腐蚀敏感性的主要原因。

Abstract:

The microstructure, mechanical properties, and corrosion resistance of ultra-high strength cold-rolled thin strips of Al-7.88Zn-2.05Mg-1.70Cu-0.19Er alloy were investigated. Results reveal that the excellent comprehensive properties of the cold-rolled thin strips with 0.5 mm in thickness are achieved after solid solution treatment of 475 °C/1 h/water quenching and double aging treatment of 120 °C/6 h+150 °C/24 h. The hardness, ultimate tensile strength, yield strength, and elongation of the thin strips are 1859.1 MPa, 669.4 MPa, 624.1 MPa, and 11.2%, respectively. The mechanical properties of double-aged strip are comparable to those of alloy after peak-aging treatment. The electrical conductivity, exfoliation corrosion rating, and stress corrosion cracking sensitivity of the thin strip are 35.5%IACS, EA, and 4.07%, respectively. The fine spherical Al₃(Er, Zr) and η? phases are uniformly distributed in the Al matrix, and most precipitates are coherent with Al matrix lattice. The tiny discontinuous grain boundary precipitate η phase mainly causes the lower stress corrosion sensitivity of the studied alloy.