The rod-shaped Mn-Ni-Fe-Ge compounds are prepared by the copper mould spraying casting. These alloys reveal the coincident martensitic magnetostructural transformation with giant room temperature magnetocaloric effect from the high-temperature paramagnetic Ni2In-type austenite to low-temperature ferromagnetic TiNiSi-type martensite. Interestingly, when the rod increases in diameter, the magnetostructural transformation temperature decreases slightly, whereas the magnetization jump and magnetocaloric properties improve. In contrast, the time of heat treatment has almost no effect on crystallographic, magnetic and magnetocaloric properties, even with fourfold elongation of annealing time. This suggests that the synthesis of rod samples by spraying casting pave a pathway for the development of new rod-shaped magnetic refrigerant with desirable magnetocaloric properties and low preparation cost due to time- and energy-saving.
