WC-HEA硬质合金的分子动力学拉伸模拟及力学性能研究  

Molecular Dynamics Tensile Simulation and Mechanical Properties of WC-HEA Cemented Carbide

作　　者：赵建玟 雷宇阳 李东波 王东[1] ZHAO Jianwen;LEI Yuyang;LI Dongbo;WANG Dong(Shool of Mechatronic Engineering,Xi’an Technological University,Xi’an 710021,Shaanxi,China)

机构地区：[1]西安工业大学机电工程学院,陕西西安710021

出　　处：《中国钨业》2024年第4期54-63,共10页China Tungsten Industry

基　　金：陕西省科技计划项目-外国专家服务计划(2024WZ-YBXM-09);大学生创新创业训练计划项目(202310702006,S202310702067)。

摘　　要：为了从纳观尺度揭示WC-CoCrNiFeCu硬质合金力学性能变化的微观机理,本研究利用分子动力学模拟了WC-HEA硬质合金在不同温度下的拉伸力学性能。在整个拉伸过程中,材料依次经历了弹性形变、塑性形变到断裂失效三个阶段。在弹性形变阶段,材料的杨氏模量为一定值;随着应力的增加,材料产生不均匀塑性变形,模型内HEA区域原子发生位错反应,并伴随着孪晶及层错的产生,HEA由原有的FCC结构部分转变为BCC结构,形成FCC+BCC的亚稳定结构,能够有效提高拉伸过程中材料的延展性,这表明WC-HEA硬质合金的塑性变形与材料的相变有关;随着模拟温度的升高,模型内原子热运动和晶格膨胀增加,导致位错产生源减少,同时部分位错相互作用并重新排列,位错数量也会相应减少,这一现象使得材料塑性得到提升的同时力学强度发生下降。采用放电等离子烧结制备了WC-HEA硬质合金刀具材料,烧结后的材料新增了BCC结构,可能是HEA中的Cr元素富集引起了这一现象的发生。当烧结温度为1 400℃时,WC-HEA硬质合金材料的综合力学性能达到最佳,其硬度为21.49 GPa,断裂韧性为16.01 MPa·m^(1/2),抗弯强度为1 293 MPa。To reveal the microscopic mechanisms underlying changes in the mechanical properties of WC-CoCrNiFeCu cemented carbide at the nanoscale, this study utilizes molecular dynamics to simulate the tensile mechanical properties of WC-HEA cemented carbide at different temperatures. Throughout the tensile process, the material undergoes three stages:elasticity, plasticity, and fracture failure. During the elastic deformation stage, the Young's modulus of the material remains constant. As stress increases, the material undergoes inhomogeneous plastic deformation, with dislocation reactions occurring in the HEA region of the model, accompanied by the formation of twins and stacking faults. The HEA partially transforms from its original FCC structure to a BCC structure, forming a metastable FCC+BCC structure, which effectively enhances the ductility of the material during tensile testing. This indicates that the plastic deformation of WC-HEA cemented carbide is related to phase transformations within the material. As the simulation temperature increases, the thermal motion of atoms and lattice expansion within the model intensify, leading to a reduction in dislocation sources. Simultaneously, some dislocations interact and rearrange, resulting in a corresponding decrease in the number of dislocations. This phenomenon enhances the plasticity of the material while reducing its mechanical strength.WC-HEA cemented carbide tool materials were prepared using spark plasma sintering. After sintering, the material exhibited an additional BCC structure, which may be due to the enrichment of Cr elements in the HEA. When the sintering temperature was 1 400 ℃, the WC-HEA cemented carbide material exhibited optimal comprehensive mechanical properties, with a hardness of 21.49 GPa, fracture toughness of 16.01 MPa·m^(1/2), and flexural strength of 1 293 MPa.

关 键 词：硬质合金 单轴拉伸 塑性形变 烧结温度 力学性能 

分 类 号：TG135.5[一般工业技术—材料科学与工程]