CrMnFeCoNi高熵合金拉伸断裂的晶体塑性有限元模拟

Tensile Fracture Behavior of the CrMnFeCoNi High Entropy Alloy:A Crystal Plasticity Finite Element Simulation

CrMnFeCoNi高熵合金的优异力学性能使其具有广阔的工程应用前景。材料力学行为的本构描述对其工程服役行为的安全评估至关重要,但是描述CrMnFeCoNi高熵合金拉伸断裂行为的本构模型少见报道。基于晶体塑性本构模型,利用Cohesive单元在多晶代表性体积单元内部植入含损伤破坏机制的晶界,模拟了CrMnFeCoNi高熵合金在单轴拉伸下的晶间断裂过程。模拟结果与试验所得的应力-应变曲线吻合较好,且能准确描述断裂发生时的应力下降过程,说明采用晶体塑性本构模型与Cohesive本构模型可以有效描述材料的宏观响应行为和断裂失效行为。进一步分析表明:裂纹从应力集中处开始萌生;随着应变的持续增加,裂纹沿着晶界扩展,最终造成断裂;晶粒随机取向对裂纹萌生位置与扩展路径有显著影响,但对宏观拉伸应力-应变曲线几乎没有影响。

The excellent mechanical properties of CrMnFeCoNi high entropy alloy make it have a broad engineering application prospect.The constitutive description of material mechanical behavior is very important for the safety assessment of its engineering service behavior,but the constitutive model describing the tensile fracture behavior of CrMnFeCoNi high entropy alloy is rarely reported.Based on the crystal plastic constitutive model,the intergranular fracture process of CrMnFeCoNi high entropy alloy under uniaxial tension is simulated by using Cohesive element to implant grain boundaries with damage mechanism in polycrystalline representative volume elements.The simulation results are in good agreement with the experimental stress-strain curves,and can accurately describe the stress decline process during fracture,indicating that the macroscopic response behavior and fracture failure behavior of materials can be effectively described by crystal plastic constitutive model and Cohesive constitutive model.Further analysis shows that the crack initiates from the stress concentration;with the continuous increase of strain,the crack propagates along the grain boundary,resulting in fracture;the random grain orientation has a significant effect on the crack initiation location and propagation path,but has almost no effect on the macroscopic tensile stress-strain curve.