Heusler alloys, such as Ni–Mn–Sn and Ni–Co–Mn–Ti, exhibit first-order magnetostructural transitions (FOMST), making them promising candidates for multicaloric cooling technologies [1-2]. Their functional performance, however, is highly sensitive to transition temperatures, thermal hysteresis and chemical composition [3-4], which are strongly affected by microstructure and processing technique. In this work, we use gas-atomized powders and Laser Powder Bed Fusion (PBF-LB/M) to process bulk samples of Ni–Mn–Sn and Ni–Co–Mn–Ti and investigate the tunability of their microstructure, FOMST, and caloric properties through process parameter control. By systematically varying laser power, scan speed, and scan strategy, we obtain tailored microstructures that enable precise adjustment of the martensitic (Ms, Mf), austenitic (As, Af), and Curie temperatures (Tc), as well as the thermal hysteresis (Thyst). Structural compositional, and magnetic characterization performed reveals clear correlations between microstructures formed under fast solidification in AM and the sharpness and reversibility of the FOMST.

We demonstrate that additive manufacturing not only preserves the functional properties of these alloys but also provides a means to actively enhance the tunability of their transition behavior compared to conventionally processed samples. These findings establish additive manufacturing as a versatile tool for engineering caloric materials transition temperatures tailored for specific applications. We gratefully acknowledge Deutsche Forschungsgemeinschaft’s (DFG) support through the CRC/TRR 270 (Project ID 405553726)

References
[1] B. Beckmann, et al, Acta Mater. (2025) 282, 120460.
[2] F. Scheibel, et al, J. Appl. Phys. (2025) 137, 014901.
[3] F. Scheibel, et al, Energy Technol. (2018) 6, 1397.
[4] F. Scheibel, et al, Acta Mater. (2023) 29, 101783