含银7055铝合金回归再时效过程中的组织与性能变化  

Retrogression and Reaging of Ag-Containing 7055 Al Alloy

作　　者：李海[1] 郑子樵[1] 王芝秀[1] 

机构地区：[1]中南大学,湖南长沙410083

出　　处：《稀有金属材料与工程》2004年第7期718-722,共5页Rare Metal Materials and Engineering

基　　金：国家973重点基础研究项目(G1999064900-9)

摘　　要：研究了回归温度(180℃,200℃,220℃)及预时效时间(12h,18h,24h)对含Ag的7055铝合金回归再时效后的强度和微观组织的影响。结果表明,由于微量Ag的添加,120℃,18h预时效处理后180℃回归再时效的强度稳定性较高,而随着回归温度的提高,再时效强度下降较快,这种现象归因于Ag的添加提高了GP区和h相的稳定性,使得GP区溶解温度升高,因而180℃回归时只发生GP区和h相的缓慢粗化,而200℃和220℃回归时发生GP区的溶解并促进h相快速粗化形成h相;实验结果显示,预时效时间对回归再时效后的强度也有较大的影响预时效时间较长或较短时(12h,24h),再时效强度随回归时间的变化较大,而经18h预时效,再时效强度稳定性较高。这种差别是由于预时效后析出相的种类和体积分数不同所致。The evolution of strength and microstructures of Ag-containing 7055 Al alloy retrogressed at 180degreesC, 200degreesC and 220degreesC and reaging at 120degreesC for 24 h was investigated. The results showed that the tendence to decrease in strength of the alloy becarne relatively slower after retrogression at 180degreesC for various times and reaging at 120degreesC for 24 h; With increase in retrogression temperature to 200degreesC and 220degreesC, the strength of the alloy after retrogression and reaging decreased rapidly. The above results were due to the addition of Ag, which increased the solvus temperature from 120similar to140degreesC to 200degreesC. As a result, GP zone coarsened at 180degreesC but reversed at 200degreesC and 220degreesC, and accelerated the formation of eta phase. Pre-aging for 12 h and 24 h at 120degreesC could form more eta' than that of pre-aging for 18 h at the initial 180degreesC retrogression stage, therefore, higher strength were the consequent result. The different trends of change in strength were attributed to coarsening of eta' phase into eta phase during prolonged retrogression and reaging.

关 键 词：AG 7055铝合金 回归再时效 组织与性能 

分 类 号：TG115[金属学及工艺—物理冶金]