SCALE BRIDGING IN DIFFUSIVE PHASE TRANSFORMATION
Ri Vala · 2009
The physical micro- and nano-scale analysis of phase transformation of materials consisting of a finite number of substitutional and interstitial components, based on the Onsager extremal thermodynamic principle, leads to a system of partial differential equations of evolution type containing certain integral term, whose form differs substantially in both phases and in the moving phase interface of finite thickness, in whose center the ideal liquid material behaviour can be detected. Even in the case of a model one-dimensional problem at certain fixed temperature, unlike e.g. the classical problems of thermal transfer, no reasonable macro-scale equations, working with material characteristics as results of some formal homogenization procedure, are available. However, the reliable evaluation both of the velocity of phase transformation and of all distributions of concentrations (or molar fractions) of particular components is needed. This paper offers a possibility of an indirect effective computational prediction of such process of diffusive and massive transformation, making use of the large database of micro-scale material properties and of the MATLAB-supported simulations, applicable even for very complicated evaluations of chemical potentials and diffusion factors.