Quantitative Inspection of Grain-Scale Chemical Inhomogeneities in High-Entropy AlB₂-Type Transition Metal Diborides

Abstract

The chemical homogeneity of single phase high-entropy AlB2-type Ti-Zr-Hf-Ta-TM diboride (TM = Cr, V, W, Mo), as well as Ti-Zr-Hf-Mo-W solid solutions was investigated using a new method based on the comparative examination of information provided by electron microscopy and structural parameters. The study of the densification behavior was accomplished, and strong correlations among densification rate-grain coarsening-long range chemical randomization were found. High-resolution synchrotron radiation X-ray diffraction supported by grain-scale chemical analyses by energy dispersive spectroscopy indicated that homogenization of the metals was incomplete, with direct impact on the refined lattice μ-strain. The chemical inhomogeneity was on the same length scale as the grain size, which makes it hardly detectable by typical chemical mapping using energy dispersive spectroscopy. Based on this analysis, the resulting μ-strain broadening is not an intrinsic property of the material, but strongly depends on its processing history.

Department(s)

Materials Science and Engineering

Comments

The authors are grateful to Elettra-Sincrotrone Trieste for providing beamtime and financial support for the SR-XRPD experiment (proposal number 20200101). The effort of L. Feng, W. Fahrenholtz, and G. Hilmas was supported by the U.S. National Science Foundation through grant CMMI-1902069. Open Access Funding provided by Consiglio Nazionale delle Ricerche within the CRUI-CARE Agreement.

Keywords and Phrases

EDS; High-Entropy Ceramics; Lattice Μ-Strain; Rietveld Refinement; SEM; Synchrotron Radiation XRD

International Standard Serial Number (ISSN)

1551-2916; 0002-7820

Document Type

Article - Journal

Document Version

Citation

File Type

text

Language(s)

English

Rights

© 2022 The American Ceramic Society, All rights reserved.

Publication Date

01 Jan 2022

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