Formation of nano-scale ω-phase in arc-melted micron-scale dendrite reinforced Zr73.5Nb9Cu7Ni1Al9.5 ultrafine composite during heat treatment

K. B. Kim, J. Das, M. H. Lee, D. H. Kim, W. H. Lee, J. Eckert

Research output: Contribution to journalArticle

3 Citations (Scopus)

Abstract

An arc-melted Zr73.5Nb9Cu7Ni1Al9.5 alloy consists of dendritic body-centered cubic solid solution and a mixture of ultrafine body-centered tetragonal Zr2Cu-type and hexagonal close-packed MgZn2-type phases in the ultrafine matrix. This composite exhibits two exothermic reactions upon heating to 973 K with a heating rate of 40 K/min. After the first exothermic reaction nano-scale ω-phase particles have formed in the β-phase dendrites indicating a decomposition of the supersaturated solid solution upon heating. At the early stage during the decomposition of the β-phase the ω-phase is coherent with the parent phase without clear structural differences. However, semicoherency between the β- and the nano-scale ω-phase regions was observed during the growth of the ω-phase. This structural semicoherency causes nano-scale twinning in the β-phase dendrites around the ordered ω-phase in order to release the mismatch energy at the interfaces between the ordered ω- and β-phases.

Original languageEnglish
Pages (from-to)538-543
Number of pages6
JournalIntermetallics
Volume16
Issue number4
DOIs
Publication statusPublished - 2008 Apr

All Science Journal Classification (ASJC) codes

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

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