Microstructure and mechanical properties of Al-Zn-Cu-Mg-Sc-Zr alloy after retrogression and re-aging treatments  

作　　者：李文斌 潘清林 肖艳苹 何运斌 刘晓艳 

机构地区：[1]School of Materials Science and Engineering,Central South University [2]School of Civil Engineering,Hunan City University

出　　处：《Journal of Central South University》2011年第2期279-284,共6页中南大学学报（英文版）

基　　金：Project(2006AA03Z523) supported by the National High-tech Research and Development Program of China

摘　　要：The mechanical properties and stress corrosion cracking （SCC） resistance of an Al-Zn-Cu-Mg-Sc-Zr alloy under different aging conditions were investigated. The dependence of microstrueture and mechanical properties on aging parameters was evaluated by tensile test, hardness test and conductivity measurement. The results show that for the alloys with retrogression and re-aging treatment （RRA）, the conductivity increases with the retrogression time and temperature, while the tensile strength decreases. The transmission electron microscopy （TEM） results show that the precipitates η（MgZn2） at grain boundary aggregate apparently with retrogression time and the precipitates inside the matrix exhibit the similar distribution to T6 temper, which comprises fine GP zones, large η＇（MgZn2）and η（MgZn2） phases. According to the mechanical properties and microstructure observations, the optimal RRA regime is recommended to be 120℃, 24h ＋ 180 ℃, 30 min ＋ 120 ℃, 24 h. The strength level of the alloy after the optimum RRA treatment is similar to that in T6 condition and the SCC resistance is improved obviously in contrast to T6 condition.The mechanical properties and stress corrosion cracking (SCC) resistance of an Al-Zn-Cu-Mg-Sc-Zr alloy under different aging conditions were investigated. The dependence of microstructure and mechanical properties on aging parameters was evaluated by tensile test, hardness test and conductivity measurement. The results show that for the alloys with retrogression and re-aging treatment (RRA), the conductivity increases with the retrogression time and temperature, while the tensile strength decreases. The transmission electron microscopy (TEM) results show that the precipitates η(MgZn2) at grain boundary aggregate apparently with retrogression time and the precipitates inside the matrix exhibit the similar distribution to T6 temper, which comprises fine GP zones, large η′(MgZn2) and η(MgZn2) phases. According to the mechanical properties and microstructure observations, the optimal RRA regime is recommended to be 120 °C, 24 h + 180 °C, 30 min + 120 °C, 24 h. The strength level of the alloy after the optimum RRA treatment is similar to that in T6 condition and the SCC resistance is improved obviously in contrast to T6 condition.

关 键 词：Al-Zn-Cu-Mg-Sc-Zr alloy retrogression and re-aging treatment microstructure mechanical properties stress corrosioncracking 

分 类 号：TG146.21[一般工业技术—材料科学与工程]