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Open AccessArticle

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

Materials Science and Technology Division, Oak Ridge National Laboratory, 1 Bethel Valley Rd, Oak Ridge, TN 37831, USA
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;
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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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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