依据热压烧结制备Ti?22Al?25Nb合金热模拟压缩所得实验数据,研究合金在热变形温度为975～1075℃、应变速率为0.001～1 s?1条件下的热变形行为.通过对数据的分析,建立包含Z参数模型、动态再结晶临界模型与动态再结晶动力学模型的新型本构关系模型.实验结果表明:Ti?22Al?25Nb合金的热变形激活能为410.172 kJ/mol,且临界应变与峰值应变之间的比值为0.67.此外,所建立的本构关系模型的预测值在应变速率为0.1 s?1、应变量小于0.1条件下与实验值相差较大,但整体上流动应力水平预测值与实验值吻合较好.并采用EBSD技术对动态再结晶动力学模型的预测精度进行分析.%The hot deformation behavior of Ti?22Al?25Nb alloy fabricated by hot compressed sintering was investigated under various conditions of compression tests in the deformation temperature range of 975?1075 ℃ with 20 ℃ intervals and the strain rate range of 0.001?1.0 s?1. Based on the experimental data, a novel constitutive relation combining a series of models was developed, including Zener?Hollomon parameter (Z), DRX critical model and kinetics model. The results show that the hot-deformed activation energy Q is calculated to be 410.172 kJ/mol, the ratio of critical strain (εc) to peak strain (εp) is a constant value of about 0.67. The predicted stress obtained by the established constitutive equations matches well with the true stress from experimental data. Despite large errors occur at the stage where strain rate is 0.1 s?1 and the values of true strain are less than 0.1, the stage of large strain should be more concerned during plastic forming. Furthermore, the predicting accuracy with the DRX kinetics model was testified by an electron back-scattered diffraction (EBSD) technique.
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