点缺陷类型和浓度对α-Fe塑性变形行为影响的分子动力学模拟  

Molecular Dynamics Simulation of the Effects of Point Defect Type and Concentration on Plastic Deformation Behavior of α-Fe

作　　者：李翔 尹益辉[1] 张元章[1] Li Xiang;Yin Yihui;Zhang Yuanzhang(Institute of Systems Engineering,China Academy of Engineering Physics,Mianyang 621999,China;School of Applied Technology,Southwest University of Science and Technology,Mianyang 621010,China)

机构地区：[1]中国工程物理研究院总体工程研究所,四川绵阳621999 [2]西南科技大学应用技术学院,四川绵阳621010

出　　处：《稀有金属材料与工程》2022年第8期2881-2891,共11页Rare Metal Materials and Engineering

基　　金：国家自然科学基金(11572298,11702280)。

摘　　要：为了深入认识点缺陷对α-Fe塑性变形行为的影响,建立含点缺陷的α-Fe试样计算模型,以点缺陷的原子浓度为变量,开展试样单轴拉伸的分子动力学模拟。研究结果表明:在相同的缺陷浓度下,不同类型的点缺陷导致的晶格畸变程度不同,因而试样发生塑性变形的难易程度就不同,其中自间隙Fe原子导致的晶格畸变程度比空位大,相应试样更容易发生塑性变形;试样的塑性变形机制随点缺陷类型和浓度而变化,进而使试样的应力-应变曲线特征发生显著变化;对于本模拟中各浓度含空位的试样,或含较低浓度自间隙Fe原子或Frenkel缺陷的试样,塑性变形表现为拉伸应力诱发的相变和位错滑移混合的机制;对于含较高浓度自间隙Fe原子或Frenkel缺陷的试样,塑性变形以位错滑移和非晶化塑性变形为主且伴随有相变。本研究加深了有关点缺陷对金属变形机制影响的认识,为后续分析多晶α-Fe材料的物理和力学性质奠定了有益的基础。In order to investigate the effects of vacancies, self-interstitial Fe atoms and Frenkel defects on the plastic deformation behavior of α-Fe under tensile load furtherly, the molecular dynamic models of the α-Fe samples with different types of the point defects were established and related simulations under uniaxial tension were carried out for a series of point defect atomic concentration of 0 %, 0.125%, 0.250%, 0.500%, 0.750% and 1.000%. The stress-strain curves was obtained, the dislocation generation and the crystal structure evolution of each α-Fe sample were observed and analyzed by the dislocation extraction algorithm and the common neighbor analysis, and the following understandings were concluded. Different types of point defects can lead to differ ent lattice distortion and related plastic deformation. Both the lattice distortion and related plastic deformation caused by self-interstitial Fe atoms are greater than those caused by vacancies at the same defect concentration. The changes of plastic deformation mechanisms induced by point defect types and concentrations make the characteristics of stress-strain curves change, i.e. the greater the concentration of self-interstitial Fe atom or Frenkel defect is, the less the distance between the upper and lower yield points on a stress-strain curve is, even vanishes, while the vacancy concentration has no such influence. Specifically, both the local amorphization and the related amorphization plastic deformation caused by self-interstitial Fe atoms are higher than those caused by vacancies. For the samples with low concentration of each of the three types point defects or for the samples with high concentration of vacancies, the plastic deformation is of a mixture of the tensile stress-induced phase transformation and the dislocation slip, while for the samples with higher concentration of self-interstitial Fe atoms(such as 0.500%, 0.750% and 1.000%) or with higher concentration of Frenkel defects(such as 0.750% and 1.000%), the plastic deformation is domi

关 键 词：Α-FE 点缺陷 相变 非晶化塑性变形 

分 类 号：TL341[核科学技术—核技术及应用]