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

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

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Single-phase face-centered cubic(fcc)high/medium-entropy alloys(H/MEAs)exhibit a much higher ten-dency 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 ex-periments 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 suc-cessive 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.

High-entropy alloysCrCoNiNanotwinsTwin nucleation

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

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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

Center for Alloy Innovation and Design(CAID),State Key Laboratory for Mechanical Behavior of Materials,Xi'an Jiaotong University,Xi'an 710049,China

Materials Sciences Division,Lawrence Berkeley National Laboratory,Berkeley,CA 94720,United States

Department of Materials Science & Engineering,University of California,Berkeley,CA 94720,United States

Beijing Key Laboratory of Advanced High Temperature Materials,Central Iron and Steel Research Institute,Beijing 100081,China

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National Natural Science Foundation of ChinaNational Natural Science Foundation of ChinaNational Natural Science Foundation of ChinaXi'an Science and Technology Planproject from the Ministry of Science and Technology of ChinaNational Natural Science Foundation of ChinaCAID by XJTUNational Natural Science Foundation of ChinaHPC platform of Xi'an Jiaotong UniversityOffice of Science,Office of Basic Energy Sciences,Materials Sciences and Engineering Division,of the U.S.Department of Energ

5223100151971167520310112017xasjl0142017YFA07007039206010212004294DE-AC02-05-CH11231

2024

10.1016/j.jmst.2023.10.025

材料科学技术(英文版)
中国金属学会 中国材料研究学会 中国科学院金属研究所

材料科学技术(英文版)

CSTPCD
影响因子：0.657
ISSN：1005-0302
年,卷(期)：2024.183(16)