Paper Title:

The Stability of γ ’-Co3(Al,W) Phase in Co-Al-W Ternary System

Periodical Materials Science Forum (Volumes 654 - 656)
Main Theme PRICM7
Edited by Jian-Feng Nie and Allan Morton
Pages 448-451
DOI 10.4028/www.scientific.net/MSF.654-656.448
Citation Yuki Tsukamoto et al., 2010, Materials Science Forum, 654-656, 448
Online since June, 2010
Authors Yuki Tsukamoto, Satoru Kobayashi, Takayuki Takasugi
Keywords Co-Al-Wternary System, Diffusion Couple, Phase Diagram
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Abstract

The thermodynamic stability ’- Co3(Al,W) phase (L12) in the Co-Al-W ternary system at 900 ºC was investigated through microstructure and EPMA analysis on a heat-treated bulk alloy. To promote microstructural evolution, the bulk alloy was cold rolled before heat treatment. By heating at 900 ºC, the ’ phase was formed discontinuously in contact with the -Co (A1) phase. With increasing heat treatment time, however, the fraction of ’ phase decreased while that of , CoAl (B2) and Co3W (D019) phases increased. These results are consistent with our previous work with a diffusion-couple method, indicating that the ’ phase is metastable, and the three phases of, CoAl and Co3W are thermodynamically stable at 900 ºC.