Fast synthesis of LaFe13-xSix magnetocaloric compounds by reactive Spark Plasma Sintering

The structural, microstructural and magnetocaloric properties of LaFe13-xSix compounds synthesized by high energy ball milling (BM) and Spark Plasma Sintering (SPS) have been investigated. The NaZn13 type phase can be directly obtained by reactive sintering at 1273 K and 50 MPa starting from a BM but not annealed sample. After sintering at 1273 K, 89 wt% of the NaZn13 phase was obtained. Its microstructure is closer to that of a sample prepared by induction melting and annealed 4 weeks at 1473 K than to a sample ball milled, annealed 30 min at 1473 K and sintered by SPS. The samples sintered by SPS present higher Curie temperatures than the reference samples, probably due to some carbon diffusion from the graphite dies occurring upon heating. Combining BM with reactive SPS allows shortening significantly the synthesis process of LaFe13-xSix compounds and shaping the material at the same time. (C) 2015 Elsevier B.V. All rights reserved.