Abstract
A computer simulation study has been performed of the reaction paths for the precipitation of δ′ (Al3Li) ordered particles from a disordered matrix (α) in Al-Li alloys, using microscopic Langévin diffusion equations. It is found that the precipitation of δ′ 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.
Original language | English (US) |
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Pages (from-to) | 245-255 |
Number of pages | 11 |
Journal | Acta Materialia |
Volume | 45 |
Issue number | 1 |
DOIs | |
State | Published - Jan 1997 |
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Ceramics and Composites
- Polymers and Plastics
- Metals and Alloys