Title: Microstructures and deformation mechanisms of the medium-entropy alloy (NiCoCr)₇₆(Ni₆AlTi)₃

Abstract

Here the microstructures and deformation mechanisms of the f.c.c. medium-entropy alloy (MEA) (NiCoCr)₇₆(Ni₆AlTi)₃ has been analyzed after various thermo-mechanical treatments. The solutionized, single-phase MEA, which had a grain size of 93.4 ± 31.9 μm, was cold-rolled (CR) to a 80% thickness reduction after which it showed both a high yield strength (YS) of 1539 MPa and a high ultimate tensile strength (UTS) of 1602 MPa, but an elongation to failure, ε, of only 16%. The CR MEA was then subjected to one of two heat treatments: (1) the CR MEA was recrystallized at 1100°C for 24 h, which produced a single-phase material with 85 ± 61.7 μm grain size that exhibited a much lower YS and UTS of 364 MPa and 747 MPa, respectively, but a much greater ε of 73%; and (2) the MEA was aged at 700°C for 24 h, which produced a fine-grained (1.1 ± 0.9 μm) material and a high volume fraction (0.35) of 12 nm dia. L1₂ nanoparticles that exhibited an excellent combination of strength and ductility, viz., YS~1501 MPa, UTS~1651 MPa, elongation ~26%. The grain boundary strengthening and precipitation strengthening were together estimated to account for ~58% of the YS in the latter material.more » After deformation, the recrystallized MEA contained numerous stacking faults and a Taylor lattice structure containing domain boundaries and microbands, while the aged MEA exhibited numerous stacking faults and sheared particles. The density of low-angle grain boundaries (LAGBs) in the recrystallized MEA increased by 100 times to 2.2 × 10^–1 μm/μm² while the density of CSL Σ3ⁿ boundaries decreased by 71% to 7.8 × 10^–3 μm/μm² after deformation. In contrast, the density of LAGBs in the aged MEA increased by 5 times to 2.6 μm/μm² while the density of CSL Σ3_n boundaries decreased by 57% to 0.6 μm/μm² after deformation.« less

Authors:

Peng, Hanlin  ^[1];

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• Search DOE PAGES for ORCID "0000-0001-5132-9293"

Hu, Ling ^[2]; Chen, Junfu ^[1]; Huang, Siming ^[2]; Li, Liejun ^[2]; Yi, Yaoyong ^[1]; Zhou, Feng ^[3]; Fang, Weiping ^[1]; Baker, Ian  ^[4]

• Search DOE PAGES for author "Baker, Ian"
• Search DOE PAGES for ORCID "0000-0001-6347-6960"

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+ Show Author Affiliations

1. Guangdong Academy of Sciences, Guangzhou (China). China-Ukraine Institute of Welding
2. South China Univ. of Technology (SCUT), Guangzhou (China)
3. Foshan Polytechnic (China)
4. Dartmouth College, Hanover, NH (United States)

Publication Date:

Thu Jun 16 00:00:00 EDT 2022

Research Org.:

Dartmouth College, Hanover, NH (United States)

Sponsoring Org.:

USDOE Office of Science (SC), Basic Energy Sciences (BES); Guangdong Academy of Sciences (GDAS); Guangzhou Municipal Science and Technology Bureau; Department of Education of Guangdong Province; China Ministry of Science and Technology

OSTI Identifier:

1977470

Alternate Identifier(s):

OSTI ID: 1961049

Grant/Contract Number:  

SC0018962; 2022GDASZH-2022010107; 2018B090904004; 2017B030314048; 201907010010; 2019GKCXTD005; 2020YFE0205300

Resource Type:

Accepted Manuscript

Journal Name:

Materials Science and Engineering. A, Structural Materials: Properties, Microstructure and Processing

Additional Journal Information:

Journal Volume: 849; Journal Issue: C; Journal ID: ISSN 0921-5093

Publisher:

Elsevier

Country of Publication:

United States

Language:

English

Subject:

36 MATERIALS SCIENCE; Science & Technology - Other Topics; Materials Science; Metallurgy & Metallurgical Engineering; Medium-entropy alloys; Microstructure; Mechanical properties; Strengthening mechanisms; Deformation mechanisms