CrCoNi中熵合金变形中位错与孪晶协调变形机制  

Coordination Deformation Mechanism Between Dislocation and Twin in CrCoNi Medium Entropy Alloy

作　　者：陈今良 冯中学[1] 易健宏[1] CHEN Jinliang;FENG Zhongxue;YI Jianhong(School of Materials Science and Engineering,Kunming University of Science and Technology,Kunming 650093,China;Institute of Vanadium and Titanium of Panzhihua University,Panzhihua 617000,Sichuan,China)

机构地区：[1]昆明理工大学材料科学与工程学院,昆明650093 [2]攀枝花学院钒钛学院,四川攀枝花617000

出　　处：《材料导报》2022年第14期178-183,共6页Materials Reports

基　　金：云南省科技厅面上基金(908075156031);钒钛资源综合利用四川省重点实验室项目(2018FTSZ41);攀枝花市科技指导计划项目(2020ZD-G-10)。

摘　　要：如何在提升材料强度的同时提升塑韧性一直是材料科学领域研究的热点之一,而这也是材料领域的重大科学难题和制约材料发展的重要瓶颈。CrCoNi中熵合金在室温与低温下都具有优异的强度和塑性,尤其在液氮温度下仍然具备高的塑性,因此备受研究者的关注。传统金属在变形初期以位错滑移为主,随变形程度增加,从而诱发孪晶,以实现孪晶与位错协调变形。与传统金属不同,CrCoNi中熵合金由于具有极低的层错能,容易在变形过程中形成大量的层错、位错和孪晶。在变形中引入纳米孪晶细化晶粒,通过细晶强化实现强度和韧性的协调提升,且孪晶可以形成立体网络提升中熵合金的协调变形能力。此外,CrCoNi合金在变形过程中,位错与孪晶存在相互作用,位错塞积后引发孪晶,孪晶进而阻碍位错运动并同时增大位错密度,调整位错滑移通道,以促使位错交滑移。如此往复,CrCoNi合金的塑性变形更加均匀,从而使强度和韧性这一矛盾得以协调。为阐述CrCoNi中熵合金在变形中呈现的优异力学性能与纳米微观结构的关系,本文从CrCoNi中熵合金的变形机理出发,综述了CrCoNi合金变形过程中位错与孪晶的存在形态、运动方式、协调机制等,分析了CrCoNi合金在不同变形条件下位错与孪晶的相互作用及二者对变形的影响,论述了位错-孪晶协同强韧化主导机制,最后对未来中熵合金的研究进行了展望。How to improve plasticity and toughness of materials while improving strength has always been one of the hotspots in the field of material scie-nce,which is also a major scientific problem in the field of materials and an important bottleneck restricting the development of materials.The CrCoNi medium entropy alloy has excellent strength and plasticity at room temperature and low temperature,especially at liquid nitrogen temperature,which attracts the attention of researchers.In the early stage of deformation,the traditional metal is mainly dislocation slip.With the increase of strain,twins are induced,and the coordinated deformation of twins and dislocations is realized.Unlike conventional metals,the CrCoNi medium entropy alloy has very low stacking fault energy,it is easy to form a large number of stacking faults,dislocations and twins in the deformation process.Nano-twins are introduced to refine grains in the deformation,and the coordinated improvement of strength and toughness is realized through fine grain strengthening.Moreover,twins can form three-dimensional network and improve the ability of coordinated deformation.In addition,during the deformation process of CrCoNi alloy,there is an interaction between dislocations and twins.After dislocation packing,twins are triggered,which hinders the movement of dislocations and improves the dislocation density.The dislocation slip channel is adjusted to promote dislocation cross slip.Thus,the plastic deformation of CrCoNi alloy is more uniform and the contradiction between strength and toughness is coordinated.In order to explain the relationship between excellent mechanical properties and nano-structure of CrCoNi medium entropy alloy during deformation,this paper starts from the deformation mechanism of CrCoNi medium entropy alloy,summarizes the existing morphology,motion mode and coordination mechanism of dislocation and twin in the deformation process of CrCoNi alloy,analyzes the interaction between dislocation and twin in CrCoNi alloy under different deformati

关 键 词：中熵合金 位错 孪晶 协调变形 强韧性 机制 

分 类 号：TG139[一般工业技术—材料科学与工程]