纯钼高压扭转过程中微纳尺度的力学性能  

Mechanical Properties of Pure Molybdenum During High-pressure Torsion Processing at Micro/nano Scale

作　　者：薛克敏[1] 王喆[1] 刘梅[1] 王雪[1] 李萍[1] Xue Kemin;Wang Zhe;Liu Mei;Wang Xue;Li Ping(Hefei University of Technology, Hefei 230009,China)

机构地区：[1]合肥工业大学

出　　处：《稀有金属材料与工程》2019年第6期2033-2037,共5页Rare Metal Materials and Engineering

基　　金：国家自然科学基金(51675154);中国博士后科学基金(2017M621994);中央高校基本科研业务费专项资金(JZ2016HGBH1054)

摘　　要：对工业烧结纯钼在室温下进行了压力为6GPa,扭转圈数为1、2和5圈的高压扭转实验,借助纳米压痕测试技术对变形前后试样进行了力学性能表征,通过有限元模拟获得了不同变形程度试样的应力-应变曲线。结果表明:高压扭转对纯钼力学性能具有显著的强化作用,变形前后试样的纳米硬度和屈服强度分别从3.02 GPa和970 MPa升高至7.80 GPa和3370 MPa。分析认为,细晶强化和位错强化是强度提升的主要因素。然而,高压扭转变形导致的位错增殖和残余应力升高使材料的弹性模量随应变量的增大而逐步降低。此外,基于有限元模拟所得的应力-应变曲线,建立了高压扭转过程中应力和等效应变之间的关系,讨论了大塑性变形过程中的硬化行为。Pure molybdenum material was processed by high-pressure torsion(HPT) at room temperature under the applied pressure of 6 GPa with different revolution number of 1, 2 and 5 turns, and the ultrafine-grained molybdenum was obtained. Nanoidentation technology was applied to characterize the mechanical properties of HPT-processed samples as well as the sintered one. The load-displacement curves,hardness and elastic modulus were obtained directly. The stress-strain curves of different samples were obtained based on the finite element simulation by using the software of Abaqus. The results show that the hardness of HPT-processed samples has an obvious increase from3.02 GPa to 7.80 GPa. Correspondingly, the yield strength increases significantly from 970 MPa to 3370 MPa. Grain refinement and dislocation tangling make the major contribution to the strength improvement. However, there is a gradual decrease in elastic modulus along with the increasing HPT revolutions, which may be due to the dislocation tangling and residual stress. The relationship between stress and equivalent strain during HPT was established based on the stress-strain curves obtained by simulation results, and the hardening behavior during HPT processing was discussed.

关 键 词：高压扭转 纯钼 纳米压痕 有限元模拟 硬化行为 

分 类 号：TG146.412[一般工业技术—材料科学与工程]