Comparative insights into microstructure and magnetism of Ni-Mn-Sn Heusler alloys manufactured by electron beam and laser beam powder bed fusion
Silja‐Katharina Rittinghaus, Hamed Shokri, Н. Ф. Шкодич, Enrico Bruder, Michael Farle, Bilal Gökce
Abstract
Powder bed fusion (PBF) is a promising but challenging method for additive manufacturing of magnetocaloric Ni-Mn-Sn Heusler alloys, due to the material's inherent brittleness. To produce crack-free near-net-shape parts from prealloyed gas atomized 47.2Ni-39.2Mn-13.0Sn powder, electron beam powder bed fusion (PBF-EB/M) with a stress-reducing spot melting scanning strategy was successfully employed. The same identical-sized powder was also processed using laser beam powder bed fusion (PBF-LB/M) for comparison. Notably different evaporation, microstructure, and magnetic characteristics were observed in the as-built conditions. Heat treatment at 900 °C resulted in almost fully martensitic phase structures, improved homogeneity, and increased the magnetocaloric effect, indicated by a magnetic entropy change up to 3.95 J/kg K and 2.07 J/kg K in 5 T for PBF-LB/M and PBF-EB/M processing of the alloy, respectively. These findings not only shed new light on the characteristics of PBF-processed Ni-Mn-Sn but also offer a promising approach to overcome the material's brittleness during manufacturing, enabling the production of mechanically stable magnets with improved magnetic properties.