微量锆对7055型铝合金淬火敏感性的影响

Influence of Trace Zr on Quench Sensitivity of 7055 Type Aluminum Alloy

摘要:

通过常温力学性能测试及用金相显微镜、扫描电镜和透射电镜研究了微量Zr对7055型铝合金淬火敏感性的影响。结果表明，Zr的添加增加了合金强度的淬火敏感性，减小了延伸率的淬火敏感性，这种影响在Zr含量〉10．1％时较明显。含Zr合金中部分再结晶的发生，不但增加了随机大角度晶界的数量，还导致Al3Zr粒子失去与基体的共格性，从而增加了合金缓冷时粗大平衡相析出的非均匀形核位置，是合金强度淬火敏感性增加的主要原因。Zr的添加阻碍再结晶，细化晶粒，是合金延伸率淬火敏感性减小的主要原因。

Abstract:

The influence of trace Zr on the quench sensitivity of 7055 type aluminum alloy was investigated by ambient tensile testing, optical microscopy(OM), scanning electron microscopy(SEM) and transmission electron microscopy(TEM). The results showed that the addition of trace Zr increased the quench sensitivity for the strength of alloy, but decreased the quench sensitivity for elongation, especially when the Zr amount was not less than 0.1%. The recrystallization occurred in the Zr-containing alloy not only increased the amount of random high angle grain boundaries, but made Al3Zr dispersoids losing the coherency with the matrix. As a result, the nucleation sites increased for heterogeneous precipitation during slow quenching, and the quench sensitivity of strength increased. The reasons for the decreased quench sensitivity of elongation were mainly due to the inhibition of recrystallization and the grain refining effect by Zr adding.