High entropy alloys with hexagonal close-packed structure derived from thin film combinatorial approach

Artashes Ter-Isahakyan, Julia S. Rau, Thomas John Balk

Research output: Contribution to journalArticlepeer-review

5 Scopus citations

Abstract

A thin film combinatorial synthesis approach was utilized to develop a compositional and structural library for the OsRuWCo alloy system. The survey of this alloy space produced 24 unique compositions and their corresponding crystal structures, which represent a phase map where amorphous and single-phase hexagonal close-packed alloys were identified. Based on the identification of a promising candidate film region, a new high entropy alloy based on OsRuWCo, but with non-equiatomic composition, was synthesized in bulk form. The alloy exhibited a single-phase hexagonal close-packed structure in the as-cast state. Three derivatives from this system were also developed by considering the heat of mixing, atomic size, and binary solubility. These new alloys are based on OsRuWCoIr and OsRuWCoFe, both of which exhibit single-phase hexagonal close-packed as-cast structures, as determined by X-ray diffraction and electron microscopy. Additionally, this large compositional space was utilized to evaluate conventional parameters that describe high entropy alloys (∆Smix, ∆Hmix, Ω, δ, and VEC), and these were found to elucidate the criteria for solid solution formation in this system. Trends illustrating the evolution from amorphous to crystalline phases are demonstrated and discussed. It is concluded that in this particular case, the dominant factors promoting crystallinity are thermodynamic or electronic, rather than geometric.

Original languageEnglish
Article number162293
JournalJournal of Alloys and Compounds
Volume893
DOIs
StatePublished - Feb 10 2022

Bibliographical note

Funding Information:
This work was supported by the U.S. Department of Energy, Office of Science, Basic Energy Sciences , under Award # DE-SC0019402 . Access to electron microscopy and related equipment was provided by the Electron Microscopy Center at the University of Kentucky, member of the National Nanotechnology Coordinated Infrastructure (NNCI), which is supported by the National Science Foundation ( ECCS-1542164 ).

Publisher Copyright:
© 2021 Elsevier B.V.

Keywords

  • High entropy alloy
  • Microstructure
  • Multi-principal element alloy
  • Order-disorder effects
  • Thin films
  • Transition metal alloys and compounds

ASJC Scopus subject areas

  • Mechanics of Materials
  • Mechanical Engineering
  • Metals and Alloys
  • Materials Chemistry

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