Direct ink writing of Nickel–Manganese–Gallium-based Heusler alloys for porous magnetic regenerator

Journal article, 2026

Nickel-Manganese-Gallium (Ni-Mn-Ga) based Heusler alloys shows enhanced magnetocaloric properties for solid-state refrigeration. However, their practical implementation required optimization of both microstructure and architecture to improved heat transfer and refrigerant performance. In this work, additive manufacturing (AM) is employed as a processing tool to systematically investigate how architectural control and processing-induced microstructural modifications influence the magnetocaloric response. Solid and hollow cylindrical structures were fabricated via Direct Ink Writing (DIW) using Ni-Mn-Ga powder. Structural characterization confirmed the formation of predominantly cubic phases, while scanning electron microscopy (SEM) revealed porous structure. Magnetization and calorimetry studies showed that the printed samples exhibited a broadened magnetocaloric transition near room temperature, minimal hysteresis, and refrigerant capacity (RC) around 118 J/kg. Comparative thermal imaging under an applied magnetic field demonstrated a stronger magnetocaloric response in the AM samples relative to their bulk counterparts. Density Functional Theory (DFT) simulations further confirmed the ferrimagnetic nature of the Mn-rich phases and explained the magnetic response in both bulk and layered configurations. These findings establish a processing-structure-property correlation and highlight the role of architectural design in tailoring magnetocaloric performance for practical cooling applications.