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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 effects of solution treatment on the quench sensitivity of Al-7.9Zn-2.5Mg-1.0Cu alloy were investigated by means of end quenching-hardness test, differential scanning calorimetry, transmission electron microscopy and scanning electron microscopy. The results show that with the increase of the distance from the quenched end surface, the hardness of the alloy sample gradually decreases. The quenching sensitivity of the sample treated at 475 ℃ for 2h is obviously higher than that of the sample treated at 450 ℃ / 8h + 475 ℃ / 2h Low, the hardened depth of more than 100mm, while the treatment system is 450 ℃ / 8h + 475 ℃ / 2h sample depth of the hardened layer is only 65mm. The solution treatment has little effect on the supersaturation of the alloy. However, compared with the sample treated at 475 ℃ / 2h, the treatment system has a recrystallization grain size of 450 ℃ / 8h + 475 ℃ / 2h, Asia) grain boundaries greatly increased, promoting the slow quenching η equilibrium phase precipitation, and the relative coarsening of the size, resulting in increased quench sensitivity.