Origin of the high propensity for nanoscale deformation twins in CrCoNi medium-entropy alloy  

作　　者：Nan-Jun Liu Zhang-Jie Wang Jun Ding Mark Asta Robert O.Ritchie Bin Gan Evan Ma Zhi-Wei Shan 

机构地区：[1]Center for Advancing Materials Performance from the Nanoscale(CAMP-Nano),State Key Laboratory for Mechanical Behavior of Materials,Xi’an Jiaotong University,Xi’an 710049,China [2]Center for Alloy Innovation and Design(CAID),State Key Laboratory for Mechanical Behavior of Materials,Xi’an Jiaotong University,Xi’an 710049,China [3]Materials Sciences Division,Lawrence Berkeley National Laboratory,Berkeley,CA 94720,United States [4]Department of Materials Science&Engineering,University of California,Berkeley,CA 94720,United States [5]Beijing Key Laboratory of Advanced High Temperature Materials,Central Iron and Steel Research Institute,Beijing 100081,China

出　　处：《Journal of Materials Science & Technology》2024年第16期63-71,共9页材料科学技术（英文版）

基　　金：supported by the National Natural Science Foundation of China(Nos.52231001,51971167,and 52031011);the Xi’an Science and Technology Plan(No.2017xasjl014);B.G.gratefully acknowledges the financial support of the project from the Ministry of Science and Technology of China(No.2017YFA0700703);the support by the National Natural Science Foundation of China(No.92060102);E.M.and J.D.acknowledge the support at CAID by XJTU.J.D.acknowledges support from the National Natural Science Foundation of China(No.12004294);the HPC platform of Xi’an Jiaotong University;supported by the Office of Science,Office of Basic Energy Sciences,Materials Sciences and Engineering Division,of the U.S.Department of Energy under Contract No.DE-AC02-05-CH11231.

摘　　要：Single-phase face-centered cubic(fcc)high/medium-entropy alloys(H/MEAs)exhibit a much higher tendency to form nanoscale deformation twins than conventional fcc metals with similar low stacking fault energies(SFEs).This extraordinary propensity for nanotwin formation in H/MEAs cannot therefore be ex-plained by their low SFEs alone.Here,using in situ compression tests of CrCoNi in comparison with Ag nanopillars inside a transmission electron microscope,we found that in the CrCoNi MEA,a high density of nanoscale twins continuously formed with an average thickness of 4.6 nm.In contrast,for similar experiments on Ag with almost identical SFE,following the nucleation of a few twins,they could further thicken to above one hundred nanometers by twin boundary migration.Molecular dynamics calculations indicated that in the highly-concentrated CrCoNi solid solution,the magnitude of the energy barriers for nucleating a stacking fault as a twin precursor in the pristine lattice and for the thickening of an existing twin both span a wide range and largely overlap with each other.Therefore,twin thickening through successive addition of atomic layers is prone to discontinuation,giving way to the nucleation of new twins at other sites where a lower energy barrier is encountered for partial-dislocation mediated fault formation.

关 键 词：High-entropy alloys CrCoNi NANOTWINS Twin nucleation 

分 类 号：TG139[一般工业技术—材料科学与工程]