Competition between continuous and discontinuous precipitation in L12-strengthened high-entropy alloys

J. Y.C. Fang, W. H. Liu, J. H. Luan, T. Yang, Y. Wu, M. W. Fu, Z. B. Jiao

Research output: Journal article publicationJournal articleAcademic researchpeer-review

Abstract

Understanding of the competition between continuous precipitation (CP) and discontinuous precipitation (DP) is crucial for tailoring the microstructure and mechanical properties of precipitation-strengthened high-entropy alloys (HEAs). In this study, the effects of aging temperature, aging time, and grain size on the CP and DP behaviors of L12-strengthened HEAs were systematically investigated. Our results reveal that low temperatures favor the DP reaction while high temperatures facilitate the CP reaction, which is related to the nucleation site and diffusion path of the two precipitation modes. At intermediate temperatures, both the CP and DP occur simultaneously and compete with each other, and the solute concentration difference across the boundaries between the two precipitation regions serves as the driving force for the sweeping of the CP regions by the DP reaction. In addition, grain size refinement can promote the DP reaction by providing more nucleation sites and more fast diffusion paths, leading to the formation of the DP-dominant microstructure. This study not only sheds light on the fundamental understanding of the CP and DP mechanisms but also provides useful guidelines for the microstructure design of advanced L12-strengthened HEAs.

Original languageEnglish
Article number107655
JournalIntermetallics
Volume149
DOIs
Publication statusPublished - Oct 2022

Keywords

  • Continuous precipitation
  • Discontinuous precipitation
  • High-entropy alloy
  • L1 precipitate
  • Temperature effect

ASJC Scopus subject areas

  • Chemistry(all)
  • Mechanics of Materials
  • Mechanical Engineering
  • Metals and Alloys
  • Materials Chemistry

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