Table-like magnetocaloric effect and enhanced refrigerant capacity of HPS La(Fe,Si)₁₃-based composites by Ce–Co grain boundary diffusion

The structure and magnetic properties of LaFe_11.6Si_1.4/Ce₄₀Co₆₀ bulk composites prepared by hot pressing sintering (HPS), followed by high-temperature diffusion annealing, were investigated. During the HPS process, the La(Fe,Si)₁₃ alloy powder particles combined with Ce₄₀Co₆₀ binder and a porous structure with high mechanical strength were obtained. The addition of Ce₄₀Co₆₀ can also promote the peritectic reaction. Annealing has important effects on the magnetocaloric properties due to the diffusion of Ce and Co into the La(Fe,Si)₁₃ phase during annealing. HPS samples were annealed at 1373 K for 24 h, and a table-like magnetocaloric effect, exhibiting a constant high magnetic entropy change (− ∆S_M) of ~ 4.0 J/(kg K) in a commercially useful temperature region of 28 K (236–264 K), was obtained for a field change of 2 T. The values of full width at half maximum of (− ∆S_M)–T plots (ΔT_FWHM) and enhanced refrigeration capacity for the composites are 55 K and 173 J/kg, respectively, for a field change of 2 T. The composites exhibit high compressive strength of up to 312 MPa. The present results indicate that LaFe_11.6Si_1.4/Ce₄₀Co₆₀ bulk composites can meet the requirement of near room temperature magnetic refrigeration based on the Ericsson cycle.