中文摘要：

以多晶体位错滑移及塑性流动机制为基础,探究了TA15钛合金在高温变形过程中介观层次上形变不均匀性和力学响应。基于率相关晶体塑性理论,建立了描述体心立方结构金属力学行为的本构模型,同时考虑了主滑移系和次滑移系的运动;确定了合理的材料本构参数,高温压缩实验与模拟得到的真应力-应变曲线基本一致。通过对TA15钛合金高温变形模拟结果进行分析,包括应力和应变分布、滑移系开动情况和晶界面积变化,得出：（1）由于晶粒几何及取向的随机性造成应力和应变分布非均匀性;（2）晶粒间相互作用的复杂性会导致各个滑移系开动的差异性;（3）形变程度越大,晶粒密度越大,晶界面积变化率越大。模拟结果为相变等显微组织演变及多尺度同步耦合提供了参考。

英文摘要：

The inhomogeneity of deformation and mechanical response of TA15 titanium alloy on a mesoscale during high temperature compression were simulated based on mechanisms of polycrystal dislocation motion and plastic flow. The constitutive model incorporating both primary slip systems and secondary slip systems was implemented to analyze the mechanical behaviour for body centered cubic based on a rate dependent crystal plasticity theory. The reasonable constitutive parameters were established on the premise of the consistency of experimental simulated stress-strain curves. The compressive simulations of TA15 titanium alloy at high temperature were analyzed, including the stress and strain distribution, the activity of slip systems, and the variation of grain boundary area. The simulations show that （i） the stress and strain distribution is inhomogeneous due to the randomness of grain geometry and orientation; （ii） the activity of slip systems is different attributing to the complex intergranular interaction; （iii） the growth rate of grain boundary area increases with increasing deformation degree and the grain density. The simulations provide a theoretical basis for solid phase transformation or microstructure evolution and multi-scale synchronous coupled simulation