时效对7055铝合金淬火敏感效应的影响

Influence of aging on quench sensitivity effect of 7055 aluminum alloy

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。

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 r/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.