On the simulation of the spinodal decomposition process and phase growth in a leadfree brazing material

Abstract

Starting from the seminal investigations made by Cahn and Hilliard in the 1950s and 1960s, Dreyer and Müller recently developed an extended diffusional equation based on the principles of Rational Thermodynamics. This equation allows for the description of nucleation and spinodal decomposition as well as subsequent phase growth observed in several alloys below a critical temperature. The intrinsic material parameters can be obtained either from literature or from calculations based on atomic interaction models (Embedded Atom Method, EAM). Starting with a setup of all relevant equations including the one for extended diffusion we then determine all material parameters required for the simulation. Furthermore we concentrate on the one-dimensional and strain-free case and explain the solution by means of Discrete Fourier Transforms (DFT) for spatial and semi-implicit Euler schemes for time discretization. Exemplary results are presented for the eutectic binary alloy AgCu which serves for brazing connections.