摘要
CoNiCrFeMn高熵合金因具高强韧性、耐磨损与抗蚀性、抗高温、耐超低温等优异性能,在深海破冰探测、超音速发动机、空天超声电机等重大应用领域可发挥重要作用。若能了解多晶CoNiCrFeMn高熵合金的微观演化特性,将推动其应用发展。因此,基于经典力学的分子动力学法,对纳米压痕诱导多晶CoNiCrFeMn高熵合金的载荷与压深曲线相对应的微结构动态演化特性进行研究,揭示出多晶CoNiCrFeMn高熵合金受载诱导的位错运动特性。研究表明,多晶CoNiCrFeMn高熵合金步入塑性变形阶段时,会出现无定型非晶化并产生位错堆垛形核,且两者均随压深增加而逐渐增多。此外,因载荷诱导产生的应力集中易导致紧密接触区晶粒内的位错发生滑移,而晶界对位错滑移起阻碍作用。随着压深持续增加,非晶化一旦到达晶界处就不再继续,而是以位错发射形式在相邻晶粒中释放应力,此时晶界成为位错发射源。研究表明:在弹性阶段,当温度低于300 K时,载荷与压深对温度不敏感;而在塑性阶段,随温度升高,载荷大幅下降。另外,温度升高易诱导多晶CoNiCrFeMn高熵合金上表面起伏程度加剧,但紧密接触边缘两侧起伏程度呈现非均匀性。本研究给出了受载响应的多晶CoNiCrFeMn高熵合金内部微结构的动态演变进程,对理解多晶CoNiCrFeMn高熵合金塑性变形机制有着重要的学术参考意义,也对后期设计具有优异力学性能的多晶CoNiCrFeMn高熵合金微结构起到重要的推动作用。
CoNiCrFeMn high-entropy alloy plays an extremely significant role in national major fields such as deep-sea detection in lower temperature,supersonic engine and space ultrasonic motor due to its excellent properties of high strength and toughness,wear resistance,corrosion resistance,high temperature softening and low temperature resistance.Therefore,it is of great significance to research its evolution process of plastic deformation.This work focused on the basic research of the correlation characteristic for CoNiCrFeMn high-entropy alloy between load versus depth curve and micro-structural evolution,and the mechanism features of its plastic defor-mation was revealed.It was noted that the amorphous phase transition and dislocation nucleation appeared simultaneously after elastic deformation,and then increase gradually as indentation depth increases.Furthermore,an interesting phenomenon of dislocation slip can be discovered in grain,which was expected to the stress concentration induced from local contact area.At the same time,the grain boundary prevents dislocation slip.As amorphous phase transition reached the grain boundary,it will not continue.Instead,the local stress concentration was released in adjacent grains with a form of dislocation emission,so that the grain boundary becomes the source of dislocation emission.On the other hand,this report showed that the load versus depth curve during elastic stage was not sensitive to temperature changes at room temperature 300 K or below,while the load at plastic stage decreases gradually with temperature increasing.Moreover,the fluctuation degree on upper surface of poly-crystalline high-entropy alloy became serious and presented heterogeneity on the both sides of local contact area due to increasing temperature.This research will provide insight on response of the micro-structure evolution induced by loading for poly-crystalline high-entropy alloy at atomic scale,which shows an important academic value on deep exploration into the plastic deformation mechanism for poly-crystalline high-entropy alloys,and provides a reference value on improving their structure and mechanical properties.
作者
黄伟玲
陈晶晶
HUANG Weiling;CHEN Jingjing(Mechanical and Electrical Engineering Department,Gannan University of Science and Technology,Ganzhou 341000,China;School of Physics and Electrical Engineering,Ningde Normal University,Ningde 352100,China)
出处
《材料导报》
EI
CAS
CSCD
北大核心
2021年第24期24107-24112,共6页
Materials Reports
基金
江西省教育厅科技计划课题(GJJ209402)
福建省自然科学基金(2017J01709
2018J01509)
宁德师范学院重大科研培育项目(2017ZDK19)。
作者简介
黄伟玲,赣南科技学院讲师,江西石城人,硕士。目前主要研究方向为机械表/界面微观接触变形行为;陈晶晶,宁德师范学院讲师,2015年于福州大学机械学院获得硕士学位。目前主要研究方向为机械表界面摩擦磨损与防护润滑。chenjingjingfzu@126.com。
