Thermo-mechanical properties of fully metallic composite phase-change materials: predictive modeling and validation by dilatometry

This paper investigates the thermo-mechanical properties of fully metallic composite phase change materials (C-PCMs) designed for thermal energy storage through phase transformations. An Al–Sn system is considered, and its effective properties are evaluated over a wide temperature range, including temperatures below and above the melting point of tin. Material properties of the constituents are taken from the literature and used in unit cell finite element simulations to derive homogenized composite properties. These results are compared with simplified analytical estimates, demonstrating that selected rules provide accurate and efficient predictions of the effective behavior. The obtained properties are subsequently used to calibrate a coupled thermo-mechanical phase mixture model implemented in COMSOL Multiphysics, enabling the simulation of phase transition processes at the macroscopic scale. Experimental validation is performed using dilatometric tests on Al–Sn specimens. The comparison shows good agreement between simulations and experiments. While the model does not explicitly account for all microstructural effects associated with the melting of tin, it accurately captures the global thermo-mechanical response, in particular the thermal expansion behavior over a broad temperature range.