Effects of CE Addition and Annealing on Microstructure, Magnetocaloric Properties and Phase Formation Kinetics of Lacexfe11co0.8si1.2 Alloys

Abstract

High-performance magnetocaloric materials are urgently required for near-room-temperature solid-state magnetocaloric refrigeration systems, which offer an attractive energy-efficient alternative to conventional gas-based technologies. However, the potential practical application of La-Fe-Co-Si based alloys is severely hindered by their low Curie temperature and prolonged annealing times required to form the desired NaZn13-type (1:13) magnetocaloric phase. In this work, we investigate the effects of Ce addition and annealing temperature on the microstructure evolution and magnetocaloric properties of LaCexFe11Co0.8Si1.2 alloys. The results demonstrates that increasing the Ce content leads to the refinement of the microstructure and significantly reduces the annealing time required to obtain a high fraction of the 1:13 phase. Furthermore, hybridization between Ce and Fe enhances the itinerant-electron metamagnetic (IEM) transition, resulting in a larger magnetic entropy change compared to La-Fe based systems. The combined effects of Ce addition and optimized annealing conditions offer a viable strategy to produce cost-effective magnetocaloric materials with improved performance near-room temperature, advancing the development of solid-state refrigeration applications.

Keywords: La-Ce-Fe-Co-Si alloy, Annealing, Phase Transformation, microstructure evolution, Magnetocaloric effect