標題: Phase transformation assisted twinning in a face-centered-cubic FeCrNiCoAl0.36 high entropy alloy
作者: Yu, Peijun
Feng, Rui
Du, Junping
Shinzato, Shuhei
Chou, Jyh-Pin
Chen, Bilin
Lo, Yu-Chieh
Liaw, Peter K.
Ogata, Shigenobu
Hu, Alice
材料科學與工程學系
Department of Materials Science and Engineering
關鍵字: High entropy alloy;Twinning;Phase transformation;First principles;Kinetic Monte Carlo
公開日期: 1-Dec-2019
摘要: The FeNiCoCr-based high entropy alloys (HEAs) exhibit excellent mechanical properties, such as twin-induced plasticity (TWIP) and phase transformation plasticity (TRIP) that can reach a remarkable combination of strength and ductility. In the present work, the face-centered-cubic (FCC) single-crystal FeNiCoCrAl0.36 HEAs were studied, using the density functional theory (DFT) combined with the phonon calculation to estimate the stacking fault energies, temperature-dependent phase stabilities of different structures. And the kinetic Monte Carlo (kMC) was used to predict the substructures evolution based on the transition state energies obtained from DFT calculations. We proposed two different formation paths of nano-twins in this Al-composited HEA and found that short-range hexagonal-close-packed (HCP)-stacking could occur in this HEA. The DFT calculations suggest that this HEA has negative stacking fault energy (SFE), HCP formation energy, and twin-formation energy at OK. Phonon calculations indicate that at the finite temperature, the competing FCC/HCP phase stability and propensity for twinning make it possible to form HCP-like twin boundaries. The kMC simulations suggest that under deformation, TWINs could form within the HCP laths which differs from the study of others. With the great agreement of results from kMC simulations and experiments, this twin-hcp laminated substructure formation path offers a new concept of designing TWIP HEAs containing tunable twin structures with HCP and TWIN lamellae structures, which could result in better mechanical properties of HEAs. (C) 2019 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
URI: http://dx.doi.org/10.1016/j.actamat.2019.10.012
http://hdl.handle.net/11536/153413
ISSN: 1359-6454
DOI: 10.1016/j.actamat.2019.10.012
期刊: ACTA MATERIALIA
Volume: 181
起始頁: 491
結束頁: 500
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