Numerical and experimental analysis of diffusioninduced aging in engineering solid mixture components

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The overall goal of the advised research project is to provide a simulation tool for studying and analysing diffusion controlled aging in realistic multicomponent structures. In order to simulate the microstructural evolution an extended Cahn-Hilliard phase-field model will be employed. The spatial approximation of the fourth-order differential equations in its weak form is based on spline functions, i.e., in the sense of isogeometric analysis we employ non-uniform rational B-splines as finite element basis functions. The major difference to existing numerical tools will be the ability of the approach to account for a realistic geometries, material compositions and loading regimes of engineering solid mixture components. Additionally to diffusion induced phase decomposition and coarsening engineering structures are typically subjected to external fields which, in turn, affect diffusion and decomposition. Exemplarily we plan to study brazing solder components. Here, a temperature gradient induced, e.g. by joule heating, together with ion migration due to current flow lead to electro-thermal diffusion. For numerical simulation of such problems a phase-field model subjected to multi-field loading needs to be solved. This requires the development of an advanced spatial and temporal discretization strategy, in particular, stabilized finite element schemes, and both, the constitutive relation as well as the numerical solution scheme have to be adapted to the coupled problem. In order to verify the numerical results experimental investigations on brazing solder are planned. In particular, temperature loading and electro-thermal diffusion induced by currency flow and joule heating will be studied experimentally and compared to simulation results.