固溶处理对Al-7.9Zn-2.5Mg-1.0Cu合金淬火敏感性的影响

Influence of Solution Treatment on the Quench Sensitivity of Al-7.9Zn-2.5Mg-1.0Cu Alloy

采用末端淬火-硬度测试、差示扫描量热法、透射电镜、扫描电镜等方法,研究了固溶处理对Al-7.9Zn-2.5Mg-1.0Cu合金淬火敏感性的影响。结果表明:随着距淬火端面距离的增加,合金试样的硬度逐渐降低,处理制度为475℃/2h试样的淬火敏感性明显比处理制度为450℃/8h+475℃/2h试样的低,其淬透层深度超过100mm,而处理制度为450℃/8h+475℃/2h试样的淬透层深度仅为65mm。固溶处理制度对合金过饱和度的影响不大,但是与处理制度为475℃/2h的试样相比,处理制度为450℃/8h+475℃/2h试样的再结晶晶粒和(亚)晶界数目大大增加,促进了慢速淬火过程中η平衡相的析出,且尺寸相对粗化,导致了淬火敏感性的提高。

The influence of solution treatment on the quench sensitivity of AI-7.9Zn-2.5Mg-1.0Cu alloy during quenching was investigated by optical microscopy（OM）, differential scanning calorimetry （DSC）, scanning electron microscopy（SEM）, transmission electron microscopy（TEM） and end quenching- hardness measurement. The results show that the hardness of different solution treatment samples decreases with the distance from quenching end increase. Moreover, the quench sensitivity of 450 ℃/8 h＋475 ℃/2 h treatment sample is higher than that of samples of 475 ℃/2 h treatment. The quenched depth is about 65mm, while that of samples of 475 ℃/2 h treatment is more than 100mm. There is few effects of solution treatment on the degree of supersaturation, While comparing to 475 ℃/2 h singlesolution sample, the number of recrystallization grains and subgrains of 450 ~CI8 h＋475 ℃/2 h doublesolution sample increase, which facilitated separation of more coarse r/ equilibrium particles in the samples of, and lead to higher quench sensitivity.