# Publications

## Ab initio prediction of the critical thickness of a precipitate

S. Sampath, R. Janisch.

Journal of Physics: Condensed Matter, **25**, 355005, (2013)

Abstract

Segregation and precipitation of second phases in metals and metallic alloys is an important
phenomenon that has a strong influence on the mechanical properties of the material. Models
exist that describe the growth of coherent, semi-coherent and incoherent precipitates. One
important parameter of these models is the energy of the interface between matrix and
precipitate. In this work we apply ab initio density functional theory calculations to obtain this
parameter and to understand how it depends on chemical composition and mechanical strain at
the interface.
Our example is a metastable Mo–C phase, the body-centred tetragonal structure, which
exists as a semi-coherent precipitate in body-centred cubic molybdenum. The interface of this
precipitate is supposed to change from coherent to semi-coherent during the growth of the
precipitate. We predict the critical thickness of the precipitate by calculating the different
contributions to a semi-coherent interface energy by means of ab initio density functional
theory calculations. The parameters in our model include the elastic strain energy stored in the
precipitate, as well as a misfit dislocation energy that depends on the dislocation core width
and the dislocation spacing. Our predicted critical thickness agrees well with experimental
observations.

DOI: 10.1088/0953-8984/25/35/355005

Download BibT

_{E}X