取向与晶界对γ-TiAl双晶塑性行为影响的CPFEM模拟

CPFEM simulation of effect of grain orientation and grain boundary on plastic behaviors of γ-TiAl bicrystals

基于晶体塑性理论和有限元方法,利用ABAQUS/UMAT二次开发接口,采用FORTRAN语言开发γ-Ti Al合金晶体塑性本构关系子程序,建立综合考虑位错滑移、形变孪晶和晶界效应的γ-Ti Al合金双晶体模型,模拟常温下不同晶粒取向差(2°、5°、8°、30°、45°和60°)与晶界效应对γ-Ti Al合金塑性变形的影响。结果显示:晶界的存在和晶粒取向差异会导致双晶体变形的不均匀性,在晶界处出现应力集中现象,且晶界区域表现出与晶粒内部区域不同的力学性质。晶界区域的受力状态受到相邻晶粒的影响,晶界角度较小时,两个晶粒滑移系的累积剪切变形较为协调,双晶体整体的塑性变形较为均匀。

Based on crystal plasticity theory and finite element method,by using ABAQUS/UMAT secondary development interface and FORTRAN language,γ-TiAl alloy crystal plasticity constitutive relation subroutine was developed andγ-TiAl bicrystals model considering dislocation slip,deformation twinning,and grain boundary effect was established,the effect of different grain orientations(2°,5°,8°,30°,45°and 60°)and grain boundary effect on plastic deformation ofγ-TiAl alloy at room temperature was simulated.The results show that the existence of grain boundary and the difference of grain orientation lead to the inhomogeneity of the bicrystals deformation,the stress concentration phenomenon appears at the grain boundary,and the grain boundary shows different mechanical properties from the internal region of grain.The stress state at grain boundary is affected by adjacent grains.When the grain boundary angle is small,the cumulative shear deformation of the two grain slip systems is relatively coordinated,and the plastic deformation of the bicrystals is relatively uniform.