PDF《时效对 7055 铝合金淬火敏感效应的影响》

第 卷第 期 中国有色金属学报 年月17

2 2007

2 Vol.

17 No.2 The Chinese Journal of Nonferrous Metals Feb.

2007 文章编号:1004-0609(2007)02-0260-05 时效对

7055 铝合金淬火敏感效应的影响 张新明,刘胜胆,游江海,张,张小艳 (中南大学 材料科学与工程学院,长沙 410083) 摘要:通过电导率、常温力学性能测试和透射电镜研究了时效对

7055 铝合金淬火敏感效应的影响.结果表明: 合金固溶后慢速淬火时,晶粒内部和晶界上析出大量粗大的 η 平衡相,基体中的溶质过饱和度及空位浓度大大降 低,不利于时效时强化相的均匀弥散析出,导致合金的力学性能下降;

双级时效对快速淬火合金的力学性能影响 不大,但提高了慢速淬火合金的力学性能,因而一定程度减少了合金的淬火敏感效应;

这是因为相对单级时效而 言双级时效可使慢速淬火合金中得到更多强化相,分布也更均匀弥散,从而减小空位浓度降低带来的不利影响;

在本研究中,100 ℃,

24 h+121 ℃,

24 h 是最佳的双级时效制度. 关键词:7055 铝合金;

时效;

淬火敏感效应 中图分类号:TG 146.1 文献标识码:A Influence of aging on quench sensitivity effect of

7055 aluminum alloy ZHANG Xin-ming, LIU Sheng-dan, YOU Jiang-hai, ZHANG Chong, ZHANG Xiao-yan (School of Materials Science and Engineering, Central South University, Changsha 410083, China) Abstract: The influence of aging on the quench sensitivity effect of

7055 aluminum alloy was investigated by electrical conductivity test, ambient temperature tensile properties test and transmission electron microscopy. The results show that many coarse equilibrium η particles precipitate in grains and on grain boundaries in the alloy during slow quenching after solution treatment, which reduces the solutes available for aging hardening. Meanwhile, the vacancy concentration is also decreased, which is unfavorable for homogeneous nucleation. Thus, the mechanical properties of slow-quenched alloy after aging are decreased. Duplex aging has slight influence on the mechanical properties of the rapid-quenched alloy, but increases that of the slow-quenched one, thus eliminates the quench sensitivity effect to some extent. This is because that duplex aging results in more amounts of dispersing and homogeneously distributing hardening precipitates, and reduces the negative effect due to lower vacancy concentration. The optimal duplex aging in this investigation is

100 ℃,

24 h+121 ℃,

24 h. Key words:

7055 aluminum alloy;

aging;

quench sensitivity effect AlZnMgCu 合金是时效强化合金,具有低密度、 高强度、较好的韧性和耐腐蚀性能而被用作航空航天 领域的结构材料[1] .该系铝合金存在淬火敏感性,即 淬火速率减小导致合金力学性能下降.这个问题对大 尺寸截面构件,如厚板而言尤显突出,因为淬火时厚 板中心较难获得大的冷却速率,造成表层和中心性能 的不均匀和整体性能的下降[2?3] . 和同系其它一些合金 相比,7055 合金中合金元素含量高,淬火敏感倾向也 更大[4] .该合金中添加 Zr 元素来控制晶粒组织,虽然 Zr 元素较 Cr 可减小合金的淬火敏感性,但淬火速率 慢时仍有粗大平衡 η 相于 Al3Zr 粒子上析出[5?6] ,对合 金力学性能产生不利影响. 基金项目:国家重点基础研究发展计划资助项目(2005CB623700);

国家教育部博士点基金资助项目(2004053304) 收稿日期:2006-06-29;