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在Gleeble-1500热模拟试验机上,对添加Zr元素的Al-Zn-Mg-Cu合金在300~450℃和0.000 5~1.000s-1变形下进行热压缩试验。采用金相显微观察(OM)、电子背散射衍射分析(EBSD)和透射电镜分析(TEM)测试技术,研究了不同热变形工艺下合金的显微组织演变规律。结果表明,随着变形温度的升高和应变速率的降低,合金的位错密度降低,亚晶尺寸增加,峰值应力减小。在热变形工艺条件下,合金组织主要由小角度晶界构成,动态软化机制主要为动态回复。在AlZn-Mg-Cu合金中添加Zr元素,生成了大量尺寸为10~25nm的弥散共格Al3Zr粒子,该粒子在热变形过程中有效钉扎位错和亚晶界,抑制热变形过程中再结晶的发生,是热变形条件下仍保持动态回复组织的原因。
On the Gleeble-1500 thermal simulator, the Al-Zn-Mg-Cu alloy with Zr addition was subjected to hot compression test at 300 ~ 450 ℃ and 0.0005 ~ 1.000s-1 deformation. The microstructure evolution of the alloy under different heat deformation process was studied by using OM, EBSD and TEM. The results show that the dislocation density decreases, the subgrain size increases and the peak stress decreases with the increase of deformation temperature and strain rate. In the hot deformation process conditions, the alloy mainly composed of small angle grain boundaries, dynamic softening mechanism is mainly dynamic response. Addition of Zr into AlZn-Mg-Cu alloy results in a large number of dispersed Al3Zr particles with the size of 10-25nm. These particles effectively pin the dislocations and the subgrain boundaries during the thermal deformation and suppress the thermal deformation Crystallization occurs under the conditions of thermal deformation still maintain the dynamic response to the organization.