Phase Transformation Induced by High Pressure Torsion in the High-Entropy Alloy CrMnFeCoNi
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In: Materials, Vol. 2022, No. 15, 8407, 25.11.2022.
Research output: Contribution to journal › Article › Research › peer-review
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TY - JOUR
T1 - Phase Transformation Induced by High Pressure Torsion in the High-Entropy Alloy CrMnFeCoNi
AU - Chulist, Robert
AU - Pukenas, Aurimas
AU - Chekhonin, Paul
AU - Hohenwarter, Anton
AU - Pippan, Reinhard
AU - Schell, Norbert
AU - Skrotzki, Werner
N1 - Publisher Copyright: © 2022 by the authors.
PY - 2022/11/25
Y1 - 2022/11/25
N2 - The forward and reverse phase transformation from face-centered cubic (fcc) to hexagonal close-packed (hcp) in the equiatomic high-entropy alloy (HEA) CrMnFeCoNi has been investigated with diffraction of high-energy synchrotron radiation. The forward transformation has been induced by high pressure torsion at room and liquid nitrogen temperature by applying different hydrostatic pressures and large shear strains. The volume fraction of hcp phase has been determined by Rietveld analysis after pressure release and heating-up to room temperature as a function of hydrostatic pressure. It increases with pressure and decreasing temperature. Depending on temperature, a certain pressure is necessary to induce the phase transformation. In addition, the onset pressure depends on hydrostaticity; it is lowered by shear stresses. The reverse transformation evolves over a long period of time at ambient conditions due to the destabilization of the hcp phase. The effect of the phase transformation on the microstructure and texture development and corresponding microhardness of the HEA at room temperature is demonstrated. The phase transformation leads to an inhomogeneous microstructure, weakening of the shear texture, and a surprising hardness anomaly. Reasons for the hardness anomaly are discussed in detail.
AB - The forward and reverse phase transformation from face-centered cubic (fcc) to hexagonal close-packed (hcp) in the equiatomic high-entropy alloy (HEA) CrMnFeCoNi has been investigated with diffraction of high-energy synchrotron radiation. The forward transformation has been induced by high pressure torsion at room and liquid nitrogen temperature by applying different hydrostatic pressures and large shear strains. The volume fraction of hcp phase has been determined by Rietveld analysis after pressure release and heating-up to room temperature as a function of hydrostatic pressure. It increases with pressure and decreasing temperature. Depending on temperature, a certain pressure is necessary to induce the phase transformation. In addition, the onset pressure depends on hydrostaticity; it is lowered by shear stresses. The reverse transformation evolves over a long period of time at ambient conditions due to the destabilization of the hcp phase. The effect of the phase transformation on the microstructure and texture development and corresponding microhardness of the HEA at room temperature is demonstrated. The phase transformation leads to an inhomogeneous microstructure, weakening of the shear texture, and a surprising hardness anomaly. Reasons for the hardness anomaly are discussed in detail.
KW - high pressure torsion
KW - high-entropy alloy
KW - microstructure
KW - phase transformation
KW - strength
KW - texture
UR - http://www.scopus.com/inward/record.url?scp=85143810866&partnerID=8YFLogxK
U2 - 10.3390/ma15238407
DO - 10.3390/ma15238407
M3 - Article
AN - SCOPUS:85143810866
VL - 2022
JO - Materials
JF - Materials
SN - 1996-1944
IS - 15
M1 - 8407
ER -
