综合提升Al-Zn-Mg-Er-Zr合金强度和耐蚀性的双级时效研究

Enhanced comprehensive properties of a novel Al-Zn-Mg-Er-Zr alloy by two-stage aging treatment

摘要:

本文以Al-Zn-Mg-Er-Zr合金为研究对象，通过硬度、电导率、力学性能、剥落腐蚀性能测试获得合金在不同时效工艺对应性能的变化规律，同时使用 EBSD、XRD、SEM 及 TEM 等组织与成分表征手段对其微观组织进行分析，阐明合金最佳综合性能与其组织模式的关系。结果表明:最优的双级时效工艺为90℃/12h+145℃/18h；此双级时效下的屈服强度为388MPa，延伸率为14.0%，剥落腐蚀评级为PB，此时合金主要强化相（GP区和η′亚稳相）在晶内大量弥散析出，晶界处的η相呈断续分布。对比该合金T6（120℃/24h）单级时效处理态，屈服强度为328MPa，延伸率为17.75%，剥落腐蚀评级为EC，双级时效后合金综合性能得到显著提升。

Abstract:

The mechanical properties and corrosion resistance of a novel Al-Zn-Mg-Er-Zr alloy under different aging processes were systematically studied. The microstructure of the alloy was analyzed by using EBSD、XRD, SEM , TEM to understand the relationship between the best comprehensive properties of the alloy and its microstructure mode. It is found that the excellent two-stage aging process is 90℃/12h+145℃/18h. The related mechanical properties including ultimate tensile strength (UTS) and elongation were 388 MPa and 14.0%. The susceptibility to exfoliation corrosion is PB. At the same time, the main strengthening phase（G.P zone and η′ phase）of the alloy are numerous precipitated in matrix, the η phase at the grain boundary is discontiguous distribution.