title: Exceptional damage-tolerance of a medium-entropy alloy CrCoNi at cryogenic temperatures.
abstract: High-entropy alloys are an intriguing new class of metallic materials that derive their properties from being multi-element systems that can crystallize as a single phase, despite containing high concentrations of five or more elements with different crystal structures. Here we examine an equiatomic medium-entropy alloy containing only three elements, CrCoNi, as a single-phase face-centred cubic solid solution, which displays strength-toughness properties that exceed those of all high-entropy alloys and most multi-phase alloys. At room temperature, the alloy shows tensile strengths of almost 1 GPa, failure strains of ∼70% and KJIc fracture-toughness values above 200 MPa  m(1/2); at cryogenic temperatures strength, ductility and toughness of the CrCoNi alloy improve to strength levels above 1.3 GPa, failure strains up to 90% and KJIc values of 275 MPa  m(1/2). Such properties appear to result from continuous steady strain hardening, which acts to suppress plastic instability, resulting from pronounced dislocation activity and deformation-induced nano-twinning.
authors.affiliation: Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.
authors.forename: Bernd
authors.identifier: http://orcid.org/0000-0002-2420-3879
authors.initials: B
authors.lastname: Gludovatz
authors.affiliation: Department of Materials Physics, Montanuniversität Leoben and Erich Schmid Institute of Materials Science, Austrian Academy of Sciences, Leoben 8700, Austria.
authors.forename: Anton
authors.initials: A
authors.lastname: Hohenwarter
authors.affiliation: Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.|Department of Materials Science and Engineering, University of California, Berkeley, California 94720, USA.
authors.forename: Keli V S
authors.initials: KV
authors.lastname: Thurston
authors.affiliation: Materials Sciences and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA.
authors.forename: Hongbin
authors.initials: H
authors.lastname: Bei
authors.affiliation: Department of Materials Sciences and Engineering, University of Tennessee, Knoxville, Tennessee 37996, USA.
authors.forename: Zhenggang
authors.initials: Z
authors.lastname: Wu
authors.affiliation: Materials Sciences and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA.|Department of Materials Sciences and Engineering, University of Tennessee, Knoxville, Tennessee 37996, USA.
authors.forename: Easo P
authors.initials: EP
authors.lastname: George
authors.affiliation: Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.|Department of Materials Science and Engineering, University of California, Berkeley, California 94720, USA.
authors.forename: Robert O
authors.identifier: http://orcid.org/0000-0002-0501-6998
authors.initials: RO
authors.lastname: Ritchie
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