A new model for grain boundary diffusion and nucleation in thin film reactions

Journal Article · Mon Aug 01 00:00:00 EDT 1994 · Acta Metallurgica et Materialia; (United States)

DOI:https://doi.org/10.1016/0956-7151(94)90232-1· OSTI ID:7019638

Coffey, K R ^[1]; Barmak, K ^[2]

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1. IBM, San Jose, CA (United States). Storage Systems Div.
2. Lehigh Univ., Bethlehem, PA (United States). Dept. of Materials Science and Engineering

The authors have used non-equilibrium thermodynamics to define the chemical potential, [mu][sub i][sup I], for each species in the grain and interphase boundaries of a polycrystalline diffusion couple. The equation for [mu][sub i][sup I] thus derived leads to a characteristic decay length, L[sub i], that describes the spatial variation of [mu][sub i][sup I]. From the values of [mu][sub i][sup I], a time dependent free energy curve of the interface,'' G[sup I], was calculated and used to define the effective driving force, [Delta]g[sup eff], for product phase nucleation as a function of time. Using this approach, product nucleation in thin film reactions is seen to be similar to precipitation from a bulk homogeneous solid solution. However, the early values for [Delta]g[sup eff] were found to be considerably lower than if the interfaces were at local equilibrium resulting in the possibility of heterogeneous nucleation of even the first phase and a new approach to phase selection.

• OSTI ID: 7019638
• Journal Information: Acta Metallurgica et Materialia; (United States), Vol. 42:8; ISSN 0956-7151
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
POLYCRYSTALS
GRAIN BOUNDARIES
NUCLEATION
MATHEMATICAL MODELS
PHASE STUDIES
THIN FILMS
CRYSTALS
FILMS
MICROSTRUCTURE
360102* - Metals & Alloys- Structure & Phase Studies
360202 - Ceramics
Cermets
& Refractories- Structure & Phase Studies
360602 - Other Materials- Structure & Phase Studies