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 LaFe11.6Si1.4/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 (- increment 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 (- increment S-M)-T plots (Delta T-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 LaFe11.6Si1.4/Ce40Co60 bulk composites can meet the requirement of near room temperature magnetic refrigeration based on the Ericsson cycle.