Title: An in situ ambient and cryogenic transmission electron microscopy study of the effects of temperature on dislocation behavior in CrCoNi-based high-entropy alloys with low stacking-fault energy

Abstract

Temperature is known to affect deformation mechanisms in metallic alloys. As temperature decreases, the stacking-fault energy in many face-centered cubic (fcc) alloys decreases, resulting in a change of deformation mode from dislocation slip to deformation twinning. Such an impact of temperature can be more complex in compositionally heterogeneous microstructures that exhibit, for example, local concentration fluctuation such as that in multi-principal element alloys. In this work, we compare the dislocation behavior and mechanical properties of a fcc Cr₂₀Mn₁₀Fe₃₀Co₃₀Ni₁₀ high-entropy alloy at ambient and liquid-nitrogen temperatures. We find that a network of stacking faults is formed by uniformly extended dislocations at ambient temperatures with low stacking-fault energy, whereas at lower temperatures, uneven dissociation of dislocations becomes significant, which results in severe dislocation pile-ups together with their pronounced entanglement. Our findings indicate that as the stacking-fault energy decreases with decreasing temperature, the heterogeneity of the distribution of elements becomes more dominant in tuning the local variation of lattice resistance. As a result, the change in dislocation behavior at low temperatures strongly affects microstructural evolution and consequently leads to significantly more pronounced work hardening.

Authors:

Fang, Yan ^[1]; Chen, Yujie ^[1]; Chen, Bing ^[2]; Li, Suzhi ^[2]; Gludovatz, Bernd  ^[3];

• Search DOE PAGES for author "Gludovatz, Bernd"
• Search DOE PAGES for ORCID "0000-0002-2420-3879"

Park, Eun Soo  ^[4];

• Search DOE PAGES for author "Park, Eun Soo"
• Search DOE PAGES for ORCID "0000-0001-8520-2012"

Sheng, Guan ^[1]; Ritchie, Robert O.  ^[5];

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

Yu, Qian  ^[1]

• Search DOE PAGES for author "Yu, Qian"
• Search DOE PAGES for ORCID "0000-0003-4413-9744"

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+ Show Author Affiliations

1. Zhejiang Univ., Hangzhou (China)
2. Xi'an Jiaotong Univ., (China)
3. Univ. of New South Wales, Sydney, NSW (Australia)
4. Seoul National Univ. (Korea, Republic of)
5. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Materials Sciences Division; Univ. of California, Berkeley, CA (United States)

Publication Date:

Mon Dec 27 00:00:00 EST 2021

Research Org.:

Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Zhejiang Univ., Hangzhou (China)

Sponsoring Org.:

USDOE Office of Science (SC), Basic Energy Sciences (BES). Materials Sciences & Engineering Division; National Science Foundation of China; National Key Research and Development Program of China; National 111 project

OSTI Identifier:

1860351

Grant/Contract Number:  

AC02-05CH11231; 51671168; 51871197; 2017YFA0208200: B16042

Resource Type:

Accepted Manuscript

Journal Name:

Applied Physics Letters

Additional Journal Information:

Journal Volume: 119; Journal Issue: 26; Journal ID: ISSN 0003-6951

Publisher:

American Institute of Physics (AIP)

Country of Publication:

United States

Language:

English

Subject:

36 MATERIALS SCIENCE; deformation; transmission electron microscopy; mechanical properties; cryogenics; alloys; crystallographic defects; chemical elements