Microstructure and Magnetocaloric Effect of Spark Plasma Sintered LaFeSi Magnets with LaAI Addition

摘要

Using LaFe11.3Si1.7 and La0.77Al0.23 alloys as precursors, the bulk LaFeSi samples with excellent magnetocaloric performance were synthesized through the spark plasma sintering (SPS) technology. The results show that the La0.77Al0.23 compound with a low melting point is helpful in facilitating peritectic reaction, and NaZn13-type phase with high content can be achieved. A slight itinerantelectron-metamagnetic transition is observed. The increased thermal annealing time facilitates magnetic transition from the first order to the second order, which is ascribed to the excessive Al diffusion into the 1: 13 phase. Under the thermal treatment condition of 1000 degrees C/6 h, the maximum entropy change (-Delta S-M)(max) of 12.40 J.kg(-1.)k(-1) can be obtained, and the highest refrigerating capacity, up to 318.40 J.kg(-1), is achieved under thermal annealing condition of 1000 degrees C/10 h.

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