Microsegregation in and Phase Stability of As-Cast Ti-Zr-Hf-Ni-Pd-Pt High-Entropy Alloys

Yoshihiko Yokoyama, Shun Itoh, Yoshihiro Murakami, Issei Narita, Gongyao Wang, Peter K. Liaw

Research output: Contribution to journalArticle

4 Citations (Scopus)

Abstract

Microsegregation in as-cast Ti-Zr-Hf-Ni-Pd-Pt high-entropy alloys (HEAs) was examined by scanning electron microscopy and transmission electron microscopy. The structure of the microsegregated HEAs was composed of dendrite grains and grain boundaries. Since Hf, Zr, and Pt show both high melting temperatures and large negative mixing enthalpy, microsegregation on a micrometer scale occurred easily, similar to the spontaneous inoculation during solidification of copper-mold casts. In contrast, the grain boundaries were identified as being Ti- and Ni-enriched regions. Macroscopic X-ray data showed the combination of a distinct body-centered-cubic structure and broad halo peaks (amorphous structure). Microstructure analysis revealed that heteroamorphous and nanocrystalline regions are observed when the Ti group:Ni group molar ratio was 50/50. This unique microsegregated structure resulted in an ultimate compression strength of more than 2 GPa.

Original languageEnglish
Pages (from-to)1474-1480
Number of pages7
JournalMetallurgical and Materials Transactions A: Physical Metallurgy and Materials Science
Volume46
Issue number4
DOIs
Publication statusPublished - 2015 Jan 1

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Mechanics of Materials
  • Metals and Alloys

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