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Phase-Separations of Coherent Precipitates of Ordered Phases in Elastically Constrained Alloys

Published online by Cambridge University Press:  26 February 2011

Minoru Doi
Affiliation:
mindoi@nitech.ac.jp, Nagoya Institute of Technology, Department of Materials Science and Engineering, Gokiso-cho, Showa-ku, Nagoya, 466-8555, Japan
Hiroshi Kumagai
Affiliation:
17415055@stn.nitech.ac.jp, Nagoya Institute of Technology, Department of Materials Science and Engineering, Gokiso-cho, Showa-ku, Nagoya, 466-8555, Japan
Kanako Nakashima
Affiliation:
17415103@stn.nitech.ac.jp, Nagoya Institute of Technology, Department of Materials Science and Engineering, Gokiso-cho, Showa-ku, Nagoya, 466-8555, Japan
Takao Kozakai
Affiliation:
kozakai@nitech.ac.jp, Nagoya Institute of Technology, Department of Materials Science and Engineering, Gokiso-cho, Showa-ku, Nagoya, 466-8555, Japan
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Abstract

Phase-separations of coherent precipitates of ordered phases were investigated by means of transmission electron microscopy (TEM) and the theoretical analysis from a thermodynamic point of view. When the two-phase microstructures of A1+L12 in elastically constrained Ni-Al-Ti and Ni-Si-Fe alloys are isothermally heated inside the two-phase region of A1+L12 , coherent L12 precipitate particles sometimes exhibit a phase-separation and A1 phase newly appears and grows in L12 particles. Phase-separations of the same type as the above are also observed in coherent two-phase microstructures of A2+D03 and A2+B2 in elastically constrained Fe-Si-V and Fe-Al-Ni alloys respectively: coherent D03 or B2 precipitates exhibit a phase-separation and A2 phase newly appears and grows in both precipitates. Such phase-separation is realized under the influence of chemical free energy and elastic energies.

Type
Research Article
Copyright
Copyright © Materials Research Society 2007

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