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Open AccessArticle

Lattice Distortion and Phase Stability of Pd-Doped NiCoFeCr Solid-Solution Alloys

1
Materials Science and Technology Division, Oak Ridge National Laboratory, 1 Bethel Valley Rd, Oak Ridge, TN 37831, USA
2
Department of Materials Science and Engineering, University of Tennessee, Knoxville, TN 37996, USA
*
Author to whom correspondence should be addressed.
Entropy 2018, 20(12), 900; https://doi.org/10.3390/e20120900
Received: 12 November 2018 / Revised: 20 November 2018 / Accepted: 21 November 2018 / Published: 25 November 2018
(This article belongs to the Special Issue New Advances in High-Entropy Alloys)
In the present study, we have revealed that (NiCoFeCr)100−xPdx (x= 1, 3, 5, 20 atom%) high-entropy alloys (HEAs) have both local- and long-range lattice distortions by utilizing X-ray total scattering, X-ray diffraction, and extended X-ray absorption fine structure methods. The local lattice distortion determined by the lattice constant difference between the local and average structures was found to be proportional to the Pd content. A small amount of Pd-doping (1 atom%) yields long-range lattice distortion, which is demonstrated by a larger (200) lattice plane spacing than the expected value from an average structure, however, the degree of long-range lattice distortion is not sensitive to the Pd concentration. The structural stability of these distorted HEAs under high-pressure was also examined. The experimental results indicate that doping with a small amount of Pd significantly enhances the stability of the fcc phase by increasing the fcc-to-hcp transformation pressure from ~13.0 GPa in NiCoFeCr to 20–26 GPa in the Pd-doped HEAs and NiCoFeCrPd maintains its fcc lattice up to 74 GPa, the maximum pressure that the current experiments have reached. View Full-Text
Keywords: solid-solution alloys; lattice distortion; phase transformation solid-solution alloys; lattice distortion; phase transformation
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MDPI and ACS Style

Zhang, F.; Tong, Y.; Jin, K.; Bei, H.; Weber, W.J.; Zhang, Y. Lattice Distortion and Phase Stability of Pd-Doped NiCoFeCr Solid-Solution Alloys. Entropy 2018, 20, 900.

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