Copper-magnesium eutectic as phase change material for thermal storage applications: Thermophysical properties and compatibility

Metallic phase change materials enable energy storage at higher temperatures than sensible-molten nitrate salt energy storage concepts. The eutectic copper‑magnesium alloy, Cu-67 wt% Mg, is an attractive phase change material due to its high thermal conductivity and melting temperature of approximately 490 °C, relevant for conventional power generation and many industrial processes. Thermophysical properties such as melting temperature, enthalpy of fusion, heat capacity in solid and liquid state and thermal conductivity has been carried out. The obtained results demonstrated a melting temperature in agreement with the calculated phase diagram as well as a high heat capacity and excellent thermal conductivity. Additionally, this work provides results of static reaction experiments of Cu-67 wt% Mg with the potential housing materials stainless steel SS304 and SS314, iron, alumina and graphite. The experimental results support the use of the Cu-67 wt% Mg alloy as phase change material in iron and graphite housings for thermal storage applications.