Laser powder bed fusion of the Ni-Mn-Sn Heusler alloy for magnetic refrigeration applications

This study aims to develop a manufacturing route for a low-cost dense magnetocaloric Ni-Mn-Sn Heusler alloy (HA) using laser powder bed fusion (LPBF) additive manufacturing technique by in-situ alloying from its elemental constituents. LPBF enables the production of high surface-area-to-volume 3D-printed components to increase heat transfer efficiency in magnetic refrigerators. A laser parametric study was performed on blocks, lattices and microchanneled cylinders for maximum densification, the highest density was observed at the samples with laser energy density (EV) of 18.52 J/mm3, 53.33 J/mm3 and 89.89 J/mm3, where they achieved a density of 6.8 g/cm3, 8.2 g/cm3 and 8.3 g/cm3, respectively. After heat treatment, the three samples show the L21 phase with a minor 4 O orthorhombic phase and double magnetic transitions, martensitie-austenite transition (TM) and curie temperature ( T C A ). The maximum magnetic entropy change ( Δ S max ) values of the three samples around TM are 0.53 Jkg-1 K-1 at 160 K, 0.5 Jkg-1 K-1 at 130 K, and 0.3 Jkg-1 K-1 at 170 K, respectively. And Δ S max of almost 1.0 Jkg-1 K-1 at T C A (∼320 K) for these samples with a field change of 1 T.