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总览 评价 胡莉莉 * ， 唐鹏 （ 华中科技大学 力学系 工程结构分析与安全评定湖北省重点实验室，湖北省武汉市，430074； ） 摘要： 金属钨因其高强度高熔点的特性多用在高温高压甚至高应率的极端工作环境中。本文利用分子动力学模拟天然的高应变率的特性，用
胡莉莉*， 唐鹏
（
华中科技大学 力学系 工程结构分析与安全评定湖北省重点实验室，湖北省武汉市，430074； ）
摘要：
金属钨因其高强度高熔点的特性多用在高温高压甚至高应率的极端工作环境中。本文利用分子动力学模拟天然的高应变率的特性，用来模拟多晶钨在高应变率下的断裂行为。分析应变率、位错运动、孔洞行核及生长等对钨的断裂力学行为的影响。计算结果表明，对纳米晶钨而言，材料的强度随着晶粒尺寸增长而增长，符合反HP效应。同时随着应变率增长而增长。拉伸过程中，微小孔洞在晶界处形核，然后沿着晶界长大，之后多处孔洞连通，是导致材料破坏的主要原因。同时少量的位错运动也可以观察到。
关键词：
单轴拉伸；多晶钨；高应变率；孔洞生长
Hu Lili*， Tang Peng
（
Hubei Key Laboratory of Engineering Structural Analysis and Safety Assessment, Department of Mechanics, Huazhong University of Science & Technology, Wuhan Hubei, 430074； ）
Abstract：
Tungsten has high strength and high melting temperature, so it is usually applied in extreme conditions even with very high strain rate. To investigate the fracture behavior of polycrystalline tungsten at very high strain rate, molecular dynamics simulation was adopted which naturally has a very high strain rate and is suitable for this paper. The influence of strain rate, dislocation motion, void formation and growth were considered on the fracture behavior of tungsten. It is found that the material strength increases with the increasing grain size, which is accordance with inverse HP effect. Also the material stregnth increases with the increasing strain rate. During the tensile process, voids were formed at the grain boundary and then grew at at the grain boudnary. After that, multiple voids were inter-connected that led to the eventual fracture of tungsten. Dislocation activities can also be observed that plays a mior role in the process.
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