微量Sc对7085铝合金淬火敏感性的影响

Effect of minor Sc on quench sensitivity of 7085 aluminum alloy

采用末端淬火实验、光学显微镜、差热分析、能谱仪和透射电镜研究微量Sc对7085铝合金淬火敏感性的影响。结果表明:在7085铝合金中添加Sc会提高该合金的淬火敏感性。添加Sc后,会在基体中形成弥散分布的Al3(Sc,Zr)粒子,该粒子能够稳定亚晶,强烈抑制再结晶,增加晶界数量;在淬火过程中,随着冷却速度的降低,粗大的平衡η相以Al3(Sc,Zr)粒子为异质形核核心析出,同时也在亚晶界上大量析出长大;η相的析出,降低了基体固溶体的过饱和度,提高了合金的淬火敏感性。

The effect of minor Sc on quench sensitivity of 7085 aluminum alloy was investigated by an end-quenching test method, optical microscopy（OM）, differential scanning calorimetry（DSC）, energy distribution spectrum（EDS） and transmission electron microscopy（TEM）. The results show that minor Sc can enhance the quench sensitivity of 7085 aluminum alloy. The A13（Sc, Zr） particles form and disperse in grain uniformly, and stabilize the subgrains, inhibite the recrystallization of the alloy strongly and increase the amount of grain boundaries. As the quenching rate decreases, however, the equilibrium MgZn2 （η） precipitates nucleate heterogeneously on A13（Sc, Zr） dispersoids and precipitate on subgrain boundaries. The precipitation of η phase reduces the solutes available for aging hardening, leading to the increase of the quench sensitivity of this alloy.