A bimodal particle size distribution enhances mechanical and magnetocaloric properties of low-temperature hot pressed Sn-bonded La0.8Ce0.2(Fe0.95Co0.05)11.8Si1.2 bulk composites

Abstract

We report a Sn-bonded La0.8Ce0.2(Fe0.95Co0.05)11.8Si1.2 bulk composite with improved mechanical and magnetocaloric properties. La0.8Ce0.2(Fe0.95Co0.05)11.8Si1.2 powders with a bimodal particle size distribution were mixed with a binder of Sn powder and hot pressed at a relatively low temperature of 423 K (150 °C). The use of bimodal size-distributed powder can reduce the non-magnetic Sn content. A bimodal particle size distribution of coarse particles (180–250 μm) and fine powders (<45 μm) resulted in particle integrity even after hot pressing. The maximum values of magnetic entropy change (−ΔSM) and adiabatic temperature change (ΔTad) increased from 7.96 J/(kg·K) (2 T), and 2.05 K (1.4 T) to 8.71 J/kg and 2.14 K, respectively, due to this microstructure. The optimized composite exhibited an enhanced compressive strength of 224 MPa and a large (−ΔSM)max of 8.71 J/(kg·K) as well as an excellent thermal conductivity of about 8.05 W/(m·K).