Microstructure, Texture, and Strength Development during High-Pressure Torsion of CrMnFeCoNi High-Entropy Alloy
by
Werner Skrotzki 1,*, Aurimas Pukenas 1, Eva Odor 2, Bertalan Joni 2, Tamas Ungar 2,3, Bernhard Völker 4, Anton Hohenwarter 4, Reinhard Pippan 5 and Easo P. George 6,7
Werner Skrotzki 1,*, Aurimas Pukenas 1, Eva Odor 2, Bertalan Joni 2, Tamas Ungar 2,3, Bernhard Völker 4, Anton Hohenwarter 4, Reinhard Pippan 5 and Easo P. George 6,7
1
Institute of Solid State and Materials Physics, Technische Universität Dresden, D-01062 Dresden, Germany
2
Department of Materials Physics, Eötvös University, H-1117 Budapest, Hungary
3
Materials Performance Centre, School of Materials, The University of Manchester, Manchester M13 9PL, UK
4
Department of Materials Science, Chair of Materials Physics, Montanuniversität Leoben, A-8700 Leoben, Austria
5
Erich Schmid Institute of Materials Science, Austrian Academy of Sciences, 8700 Leoben, Austria
6
Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
7
Department of Materials Science and Engineering, University of Tennessee, Knoxville, TN 37996, USA
*
Author to whom correspondence should be addressed.
Crystals 2020, 10(4), 336; https://doi.org/10.3390/cryst10040336
Received: 27 March 2020 / Revised: 19 April 2020 / Accepted: 20 April 2020 / Published: 24 April 2020
(This article belongs to the Special Issue Crystal Plasticity)
The equiatomic face-centered cubic high-entropy alloy CrMnFeCoNi was severely deformed at room and liquid nitrogen temperature by high-pressure torsion up to shear strains of about 170. Its microstructure was analyzed by X-ray line profile analysis and transmission electron microscopy and its texture by X-ray microdiffraction. Microhardness measurements, after severe plastic deformation, were done at room temperature. It is shown that at a shear strain of about 20, a steady state grain size of 24 nm, and a dislocation density of the order of 1016 m−2 is reached. The dislocations are mainly screw-type with low dipole character. Mechanical twinning at room temperature is replaced by a martensitic phase transformation at 77 K. The texture developed at room temperature is typical for sheared face-centered cubic nanocrystalline metals, but it is extremely weak and becomes almost random after high-pressure torsion at 77 K. The strength of the nanocrystalline material produced by high-pressure torsion at 77 K is lower than that produced at room temperature. The results are discussed in terms of different mechanisms of deformation, including dislocation generation and propagation, twinning, grain boundary sliding, and phase transformation.
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Keywords:
high-entropy alloy; high-pressure torsion; microstructure; texture; phase transformation; strength
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MDPI and ACS Style
Skrotzki, W.; Pukenas, A.; Odor, E.; Joni, B.; Ungar, T.; Völker, B.; Hohenwarter, A.; Pippan, R.; George, E.P. Microstructure, Texture, and Strength Development during High-Pressure Torsion of CrMnFeCoNi High-Entropy Alloy. Crystals 2020, 10, 336.
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