Assessing Mg₈₄Cu₁₆ as a novel PCM for high-temperature energy storage: Focus on thermal stability and material compatibility

¹ Laboratory of Sustainable Development, Faculty of Sciences and Technologies, Sultan Moulay Slimane University, Beni Mellal, 23000, Morocco
² Laboratory of Inorganic Materials for Sustainable Energy Technology (LIMSET), UM6P, Benguerir, 43150, Morocco.
³ Centre for Cooperative Research on Alternative Energies (CIC energiGUNE), Basque Research and Technology Alliance (BRTA), 01510 Alava, Spain.

^* Corresponding author: This email address is being protected from spambots. You need JavaScript enabled to view it.

Abstract

The development of efficient latent heat storage materials for high-temperature thermal energy systems is essential to improving the performance and reliability of concentrated solar power (CSP) plants. This study evaluates the thermal resilience and chemical compatibility of the Mg₈₄Cu₁₆ eutectic alloy, which has emerged as a promising phase change material (PCM) due to its high thermal conductivity and favorable melting properties. Accelerated cycling tests (30 cycles between 300–550 °C) were performed to assess the alloy's structural and thermophysical stability. Post-cycling characterization using SEM-EDS and DSC showed negligible degradation in microstructure and thermal performance, with melting point and latent heat remaining stable at ~488°C and ~232 J/g, respectively. Furthermore, static corrosion tests with stainless steels (SS304, SS316) and Inconel at 550 °C for 240 hours demonstrated moderate compatibility with stainless steels and excellent resistance in Inconel. To the best of our knowledge, this is the first study to evaluate the corrosion resistance of Mg₈₄Cu₁₆ under prolonged high-temperature exposure (550°C for 240 h), providing new insights into its long-term compatibility with containment materials. These findings confirm that Mg₈₄Cu₁₆ maintains structural and thermal stability under operational conditions, making it a strong candidate for high-temperature latent heat storage systems in industrial energy applications.