Abstract
The phase equilibria and ordering reactions in the b.c.c. aluminides of the Ni-Al-Ti-Fe system at 800-1300°C have been investigated mainly by the diffusion couple method. The compositions of the β (B2: (Ni,Fe)(Al,Ti)) and H (L21: (Ni5Fe)2AlTi) phases in equilibrium, the critical boundaries of the continuous ordering transition and the tricritical points have been determined. It is shown that the miscibility gap boundary between the β and H phases, tie line configurations and the β-H second order reaction can all be depicted inside a composition square whose corners are made up of NiAl-NiTi-FeAl-FeTi, respectively, i.e. (Ni,Fe)-50 at.% (Al,Ti). The stability region of the Heusler phase and the β + H immiscibility gap in the NiAl-NiTi pseudo-binary system are narrowed down by increasing the Fe content. The phase stability of these ordered b.c.c. aluminides is presented and discussed.
Original language | English |
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Pages (from-to) | 235-244 |
Number of pages | 10 |
Journal | Materials Science and Engineering A |
Volume | 239-240 |
Issue number | 1-2 |
DOIs | |
Publication status | Published - 1997 Dec |
Keywords
- B2 phase
- FeAlTi alloy
- L2 phase
- Miscibility gap
- NiAl
- Order-disorder transition
- Phase stability
- Ti alloy
- Tricritical point
- b.c.c. aluminides
ASJC Scopus subject areas
- Materials Science(all)
- Condensed Matter Physics
- Mechanics of Materials
- Mechanical Engineering