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Title: Phase transformations of Al-bearing high-entropy alloys Al xCoCrFeNi (x = 0, 0.1, 0.3, 0.75, 1.5) at high pressure

Pressure-induced structural modifications in high-entropy alloys with varying Al contents, Al xCoCrFeNi (x = 0, 0.1, 0.3, 0.75, 1.5), have been investigated at pressures up to ~50 GPa by synchrotron X-ray diffraction and, following depressurization, by transmission electron microscopy (TEM). In Al xCoCrFeNi compounds with x ≤ 0.3, all of which exhibit an initial single-phase face-centered cubic (fcc) structure, proportionality between the Al content and the critical pressure for transformation to hexagonal close-packed (hcp) phases, distinguished by a distinct planar stacking sequence, is observed. This is attributed to the structural distortion arising from the large size of Al atoms relative to those of the other constituent elements, which results in an increase in the formation energy of stacking faults and a decrease in compressibility. High-resolution TEM results demonstrate variation of the stacking sequence from ABCABC, typical of fcc materials, to ABABAB, typical of hcp materials, in CoCrFeNi following high pressure. In Al 0.75CoCrFeNi, which exhibits an initial dual-phase structure [fcc and body-centered cubic (bcc)], the result again shows the formation of a (hcp) phase despite its higher Al content, suggesting that the bcc phase may be more amenable to pressure-induced phase modification than is the fcc phase, which is absentmore » for lower Al contents. However, the trend of transformation inhibition by increasing the Al content is again observed, with Al 1.5CoCrFeNi retaining its initial structure up to the highest pressure achieved. Furthermore the determination of these compositional trends in the high-pressure phase response of these materials may enable the production of new phase mixtures with precisely tuned phase proportions and potentially desirable properties.« less
Authors:
 [1] ; ORCiD logo [2] ;  [1] ;  [1] ;  [1] ;  [3] ;  [4] ;  [5] ;  [4] ;  [5] ; ORCiD logo [6] ;  [7] ;  [1]
  1. Stanford Univ., Stanford, CA (United States)
  2. Stanford Univ., Stanford, CA (United States); Harvard Univ., Cambridge, MA (United States)
  3. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
  4. Univ. of Tennessee, Knoxville, TN (United States)
  5. Peking Univ., Beijing (China)
  6. Univ. of Science and Technology Beijing, Beijing (China)
  7. Stanford Univ., Stanford, CA (United States); SLAC National Accelerator Lab., Menlo Park, CA (United States)
Publication Date:
Grant/Contract Number:
AC02-76SF00515; 11675005; 51471025; 51671020
Type:
Accepted Manuscript
Journal Name:
Applied Physics Letters
Additional Journal Information:
Journal Volume: 114; Journal Issue: 9; Journal ID: ISSN 0003-6951
Publisher:
American Institute of Physics (AIP)
Research Org:
SLAC National Accelerator Lab., Menlo Park, CA (United States)
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE
OSTI Identifier:
1504572

Wang, Chenxu, Tracy, Cameron L., Park, Sulgiye, Liu, Jin, Ke, Feng, Zhang, Fuxiang, Yang, Tengfei, Xia, Songqin, Li, Congyi, Wang, Yugang, Zhang, Yong, Mao, Wendy L., and Ewing, Rodney C.. Phase transformations of Al-bearing high-entropy alloys AlxCoCrFeNi (x = 0, 0.1, 0.3, 0.75, 1.5) at high pressure. United States: N. p., Web. doi:10.1063/1.5079868.
Wang, Chenxu, Tracy, Cameron L., Park, Sulgiye, Liu, Jin, Ke, Feng, Zhang, Fuxiang, Yang, Tengfei, Xia, Songqin, Li, Congyi, Wang, Yugang, Zhang, Yong, Mao, Wendy L., & Ewing, Rodney C.. Phase transformations of Al-bearing high-entropy alloys AlxCoCrFeNi (x = 0, 0.1, 0.3, 0.75, 1.5) at high pressure. United States. doi:10.1063/1.5079868.
Wang, Chenxu, Tracy, Cameron L., Park, Sulgiye, Liu, Jin, Ke, Feng, Zhang, Fuxiang, Yang, Tengfei, Xia, Songqin, Li, Congyi, Wang, Yugang, Zhang, Yong, Mao, Wendy L., and Ewing, Rodney C.. 2019. "Phase transformations of Al-bearing high-entropy alloys AlxCoCrFeNi (x = 0, 0.1, 0.3, 0.75, 1.5) at high pressure". United States. doi:10.1063/1.5079868.
@article{osti_1504572,
title = {Phase transformations of Al-bearing high-entropy alloys AlxCoCrFeNi (x = 0, 0.1, 0.3, 0.75, 1.5) at high pressure},
author = {Wang, Chenxu and Tracy, Cameron L. and Park, Sulgiye and Liu, Jin and Ke, Feng and Zhang, Fuxiang and Yang, Tengfei and Xia, Songqin and Li, Congyi and Wang, Yugang and Zhang, Yong and Mao, Wendy L. and Ewing, Rodney C.},
abstractNote = {Pressure-induced structural modifications in high-entropy alloys with varying Al contents, AlxCoCrFeNi (x = 0, 0.1, 0.3, 0.75, 1.5), have been investigated at pressures up to ~50 GPa by synchrotron X-ray diffraction and, following depressurization, by transmission electron microscopy (TEM). In AlxCoCrFeNi compounds with x ≤ 0.3, all of which exhibit an initial single-phase face-centered cubic (fcc) structure, proportionality between the Al content and the critical pressure for transformation to hexagonal close-packed (hcp) phases, distinguished by a distinct planar stacking sequence, is observed. This is attributed to the structural distortion arising from the large size of Al atoms relative to those of the other constituent elements, which results in an increase in the formation energy of stacking faults and a decrease in compressibility. High-resolution TEM results demonstrate variation of the stacking sequence from ABCABC, typical of fcc materials, to ABABAB, typical of hcp materials, in CoCrFeNi following high pressure. In Al0.75CoCrFeNi, which exhibits an initial dual-phase structure [fcc and body-centered cubic (bcc)], the result again shows the formation of a (hcp) phase despite its higher Al content, suggesting that the bcc phase may be more amenable to pressure-induced phase modification than is the fcc phase, which is absent for lower Al contents. However, the trend of transformation inhibition by increasing the Al content is again observed, with Al1.5CoCrFeNi retaining its initial structure up to the highest pressure achieved. Furthermore the determination of these compositional trends in the high-pressure phase response of these materials may enable the production of new phase mixtures with precisely tuned phase proportions and potentially desirable properties.},
doi = {10.1063/1.5079868},
journal = {Applied Physics Letters},
number = 9,
volume = 114,
place = {United States},
year = {2019},
month = {3}
}

Works referenced in this record:

Nanostructured High-Entropy Alloys with Multiple Principal Elements: Novel Alloy Design Concepts and Outcomes
journal, May 2004
  • Yeh, J.-W.; Chen, S.-K.; Lin, S.-J.
  • Advanced Engineering Materials, Vol. 6, Issue 5, p. 299-303
  • DOI: 10.1002/adem.200300567