考虑位错密度和损伤的NiCoCrFe高熵合金晶体塑性有限元分析  

Crystal plasticity finite element analysis of NiCoCrFe high entropy alloy considering dislocation density and damage

作　　者：胡广 赵英杰 马胜国 张团卫[1,2,3] 赵聃 王志华 HU Guang;ZHAO Yingjie;MA Shengguo;ZHANG Tuanwei;ZHAO Dan;WANG Zhihua(Institute of Applied Mechanics,College of Mechanical and Vehicle Engineering,Taiyuan University of Technology,Taiyuan 030024,China;Shanxi Key Laboratory of Material Strength&Structural Impact,Taiyuan 030024,China;Mechanics National Experimental Teaching Demonstration Center,Taiyuan University of Technology,Taiyuan 030024,China)

机构地区：[1]太原理工大学机械与运载工程学院应用力学研究所,太原030024 [2]材料强度与结构冲击山西省重点实验室,太原030024 [3]太原理工大学力学国家级实验教学示范中心,太原030024

出　　处：《材料工程》2022年第3期60-68,共9页Journal of Materials Engineering

基　　金：国家自然科学基金(11602158,12072220,11572214);山西省自然科学基金(201901D111088);中国博士后基金(2020M673473)。

摘　　要：结合实验和晶体塑性有限元方法研究准静态加载NiCoCrFe高熵合金有限变形过程中的宏观和微观力学响应、损伤行为以及微观结构演化。使用电子背散射衍射技术(EBSD)对拉伸实验变形前后NiCoCrFe的微观结构进行表征。通过修改强化模型和流动准则分别在CPFEM模型中引入位错密度内部状态变量和连续介质损伤因子,并结合拉伸实验应力-应变曲线确定NiCoCrFe相关的模型参数。结果表明:考虑位错密度和损伤的CPFEM模型可以有效地描述NiCoCrFe宏观和微观力学响应。CPFEM模型合理预测NiCoCrFe颈缩区域的变形形状和尺寸,其中实验获得的颈缩区域长度比预测结果小7%,CPFEM预测的颈缩区域宽度比实验结果大23%。CPFEM模型预测NiCoCrFe拉伸变形后的织构演化同EBSD表征结果大致相同,均表现为弱的(100)∥RD以及强的(111)∥RD纤维织构。在三维微观结构损伤分析中,CPFEM模型预测的损伤在应力集中以及位错密度集中的晶界处萌生,表现为晶间损伤机制,并且随着变形的增加损伤逐渐向晶粒内部扩展。Macroscopic and microscopic mechanical responses,damage behavior and microstructure evolution of NiCoCrFe high entropy alloys(HEAs)during finite deformation under quasi-static loading were investigated by experiments and crystal plasticity finite element method.The microstructure of NiCoCrFe before and after tensile deformation was characterized by electron backscattering diffraction technique(EBSD).The internal state variables of dislocation density and continuum damage factors were introduced into the CPFEM model by modifying the strengthening model and the flow criterion,and the NiCoCrFe related model parameters were determined by combining the stress-strain curves of the tensile test.The results show that the CPFEM model considering the dislocation density and damage can effectively describe the macroscopic and microscopic mechanical responses of NiCoCrFe.CPFEM model can reasonably predict the deformation shape and size of NiCoCrFe necking region,among which,the length of the necking region obtained in the experiment is 7%smaller than the predicted result,and the width of the necking region predicted by CPFEM is 23%larger than the experimental result.The texture evolution predicted by CPFEM model after NiCoCrFe tensile deformation is in good agreement with the results that characterized by EBSD,showing weak(100)∥RD and strong(111)∥RD fiber texture.In the analysis of the 3D micro-structure damage,the damage predicted by the current CPFEM model appears as an inter-granular damage mechanism at the grain boundary where stress and dislocation density are concentrated,and the damage gradually expands to the grain interior with the increase of deformation.

关 键 词：高熵合金 晶体塑性有限元 损伤 位错密度 织构 

分 类 号：TB301[一般工业技术—材料科学与工程] O344.1[理学—固体力学]