Computer simulation of the kinetics of order-disorder and phase separation during precipitation of {delta}{prime} (Al{sub 3}Li) in Al-Li alloys
- Pennsylvania State Univ., University Park, PA (United States). Dept. of Materials Science and Engineering
A computer simulation study has been performed of the reaction paths for the precipitation of {delta}{prime} (Al{sub 3}Li) ordered particles from a disordered matrix ({alpha}) in Al-Li alloys, using microscopic Langevin diffusion equations. It is found that the precipitation of {delta}{prime} occurs either by a congruent ordering process followed by decomposition, or by a non-classical nucleation mechanism which requires critical fluctuations of both composition and order parameter, except in a narrow range of compositions near the equilibrium phase boundary of the disordered phase, where classical nucleation theory seems to be applicable. Composition and order parameter profiles across a critical nucleus were obtained for different compositions in the nucleation and growth regime, and compared with those obtained from the continuum non-classical nucleation theory. Possible origins for the discrepancies in the precipitation mechanism, obtained from different theoretical and experimental studies, are suggested.
- OSTI ID:
- 445339
- Journal Information:
- Acta Materialia, Journal Name: Acta Materialia Journal Issue: 1 Vol. 45; ISSN 1359-6454; ISSN ACMAFD
- Country of Publication:
- United States
- Language:
- English
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