摘要
位错是金属塑性变形普遍形式,对其可动位错演化特性与规律探寻并充分利用,将在金属强韧化提升中有着潜在基础前瞻性研究价值.本文基于分子动力学法对金属Al塑性变形的可动位错迁演特性展开研究,洞悉纳米压痕诱导的可动位错与孪晶界面间作用规律,揭示出金属强化微观机制,并分析单层孪晶界高度与多层孪晶界层间距对可动位错迁演、位错密度、硬度、黏着效应的影响.研究发现:高速变形下的金属非晶产生和密排六方结构的出现会协同主导Al基塑性变形,而孪晶界会阻碍可动位错滑移、诱导可动位错缠绕及交滑移产生,在金属承载提升中扮演了位错墙和诱导位错胞形成的微观作用.通过在孪晶界形成钉扎位错和限制位错迁移,在受限域形成高密度局域可动位错,显著强化了金属硬度和韧性,降低了卸载时黏附于探针表面的原子数.结果表明:Al基受载会诱导上表面局部非接触区原子失配斑出现;单层孪晶界高度离基底上表面距离减小时,位错缠绕和交滑移作用越明显,抗黏着效应也随之下降;载荷持续增加会诱驱孪晶界成为位错萌生处与发射源,并伴随塑性环的繁衍增殖.
It is an universal phenomenon that the dislocations are produced in metal plastic deformation,which will has a potential value in fundamental research field for metal strengthening and toughening if its evolution characteristics and laws are investigated.Therefore,this behavior of movable dislocation for metal Al is studied by atomic simulation,and the microscopic mechanism of metal strengthening and toughening are also revealed through studying the interaction between movable dislocation induced by nano-indentation and twin boundary.Furthermore,the movable dislocation features,and dislocation density,and hardness,and adhesive effect are analyzed,and the comparison between the single boundary height and the multilayer twin boundary height is conducted.It is found that the plastic deformation of aluminum mental can be dominant by coordinating the amorphous generation and hexagonal close-packed structure under high speed deformation.In the nanoindentation process,the twin boundary has two obvious effects on movable dislocation of moving changes:one is to hinder the dislocation from migrating,the other is to induce dislocation to produce a cell,which result in the dislocation entanglement and generation of cross slip,it is also the main reason why the metal has excellent mechanical properties of strengthening and toughening features.These results demonstrate that the local noncontact region on the surface of Al substrate can induce atomic mismatch spots to appear during loading,and when the distance between the twin boundary and the upper surface of the substrate decreases,the effects of dislocation winding and dislocation slip become more obvious,and the anti-adhesion effect also decreases.In addition,the twin boundary is treated as the propagation of plastic ring source in the dislocation emission process when substrate is continuously loaded.These results provide an important theoretical source for improving metal strengthening and toughening effect.
作者
王胜
陈晶晶
翁盛槟
Wang Sheng;Chen Jing-Jing;Weng Sheng-Bin(Department of Mechanical Engineering,Quzhou College of Technology,Quzhou 324000,China;School of Information and Mechatronics Engineering,Ningde Normal University,Ningde 352100,China;Engineering Training Center,Quzhou University,Quzhou 324000,China)
出处
《物理学报》
SCIE
EI
CAS
CSCD
北大核心
2022年第2期371-379,共9页
Acta Physica Sinica
基金
浙江省基础公益研究计划(批准号:LGC21E050002)
福建省自然科学基金(批准号:2017J01709,2018J01556)
衢州市科技计划(批准号:2020K17)
浙江省教育厅一般科研项目(批准号:Y202044634)
宁德师范学院重大科研培育项目(批准号:2017ZDK19)资助的课题。
关键词
纳米压痕
可动位错
分子动力学
金属强韧化
孪晶界
黏着效应
nano-indentation
movable dislocation
molecular dynamics
strengthening and toughening
twin boundary
adhesive effect
