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Science. 2014 Sep 5;345(6201):1153-8. doi: 10.1126/science.1254581.

A fracture-resistant high-entropy alloy for cryogenic applications.

Author information

1
Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA.
2
Department of Materials Physics, Montanuniversität Leoben and Erich Schmid Institute of Materials Science, Austrian Academy of Sciences, Leoben 8700, Austria.
3
Materials Sciences and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA.
4
Materials Sciences and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA. Materials Sciences and Engineering Department, University of Tennessee, Knoxville, TN 37996, USA. georgeep@ornl.gov roritchie@lbl.gov.
5
Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA. Department of Materials Science and Engineering, University of California, Berkeley, CA 94720, USA. georgeep@ornl.gov roritchie@lbl.gov.

Abstract

High-entropy alloys are equiatomic, multi-element systems that can crystallize as a single phase, despite containing multiple elements with different crystal structures. A rationale for this is that the configurational entropy contribution to the total free energy in alloys with five or more major elements may stabilize the solid-solution state relative to multiphase microstructures. We examined a five-element high-entropy alloy, CrMnFeCoNi, which forms a single-phase face-centered cubic solid solution, and found it to have exceptional damage tolerance with tensile strengths above 1 GPa and fracture toughness values exceeding 200 MPa·m(1/2). Furthermore, its mechanical properties actually improve at cryogenic temperatures; we attribute this to a transition from planar-slip dislocation activity at room temperature to deformation by mechanical nanotwinning with decreasing temperature, which results in continuous steady strain hardening.

PMID:
25190791
DOI:
10.1126/science.1254581
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