Title: Short-range order and its impact on the CrCoNi medium-entropy alloy

Abstract

Traditional metallic alloys are mixtures of elements in which the atoms of minority species tend to be distributed randomly if they are below their solubility limit, or to form secondary phases if they are above it. The concept of multiple-principal-element alloys has recently expanded this view, as these materials are single-phase solid solutions of generally equiatomic mixtures of metallic elements. This group of materials has received much interest owing to their enhanced mechanical properties^1,2,3,4,5. They are usually called medium-entropy alloys in ternary systems and high-entropy alloys in quaternary or quinary systems, alluding to their high degree of configurational entropy. However, the question has remained as to how random these solid solutions actually are, with the influence of short-range order being suggested in computational simulations but not seen experimentally^6,7. In this paper we report the observation, using energy-filtered transmission electron microscopy, of structural features attributable to short-range order in the CrCoNi medium-entropy alloy. Increasing amounts of such order give rise to both higher stacking-fault energy and hardness. These findings suggest that the degree of local ordering at the nanometre scale can be tailored through thermomechanical processing, providing a new avenue for tuning the mechanical properties of medium- and high-entropy alloys.

Authors:

Zhang, Ruopeng  ^[1];

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• Search DOE PAGES for ORCID "0000-0001-7677-4051"

Zhao, Shiteng ^[1]; Ding, Jun ^[2]; Chong, Yan ^[1]; Jia, Tao ^[3]; Ophus, Colin ^[4]; Asta, Mark  ^[5];

• Search DOE PAGES for author "Asta, Mark"
• Search DOE PAGES for ORCID "0000-0002-8968-321X"

Ritchie, Robert O.  ^[6];

• Search DOE PAGES for author "Ritchie, Robert O."
• Search DOE PAGES for ORCID "0000-0002-0501-6998"

Minor, Andrew M.  ^[1]

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• Search DOE PAGES for ORCID "0000-0003-3606-8309"

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+ Show Author Affiliations

1. Univ. of California, Berkeley, CA (United States). Dept. of Materials Science and Engineering; Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). National Center for Electron Microscopy
2. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Materials Sciences Division
3. Stanford Univ., CA (United States). Dept. of Physics
4. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). National Center for Electron Microscopy
5. Univ. of California, Berkeley, CA (United States). Dept. of Materials Science and Engineering; Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Materials Sciences Division
6. Univ. of California, Berkeley, CA (United States). Dept. of Materials Science and Engineering; ; Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Materials Sciences Division

Publication Date:

Wed May 20 00:00:00 EDT 2020

Research Org.:

Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)

Sponsoring Org.:

USDOE Office of Science (SC), Basic Energy Sciences (BES). Materials Sciences & Engineering Division; US Department of the Navy, Office of Naval Research (ONR); National Science Foundation (NSF)

OSTI Identifier:

1635190

Grant/Contract Number:  

AC02-05CH11231; N00014-12-1-0413; N00014-17-1-2283; N00014-11-1–0886; ECCS-1542152

Resource Type:

Accepted Manuscript

Journal Name:

Nature (London)

Additional Journal Information:

Journal Name: Nature (London); Journal Volume: 581; Journal Issue: 7808; Journal ID: ISSN 0028-0836

Publisher:

Nature Publishing Group

Country of Publication:

United States

Language:

English

Subject:

36 MATERIALS SCIENCE; metals and alloys; transmission electron microscopy; medium-/high-entropy alloys; short-range order; energy-filtered transmission electron microscopy