A rotary active magnetic regeneration refrigerator prototype named FAME Cooler was developed for studying the performance of different magnetocaloric materials in a realistic practical environment. The rotary magnetic field source generates an average magnetic field of 0.875 T within a volume of 0.71 l The regenerator is designed asymmetrically and holds in total 1.18 kg of gadolinium spheres for a first performance test. Combined with a real-time controlled programmable solenoid-valves system, different working parameters or thermodynamic cycles can be applied. In the performance test, while the temperature of system hot side was fixed at 295 K, under a utilization condition of 0.25, this prototype achieved a maximum zero-span cooling power of 162.4 W, and a zero-power temperature span of 11.6 K. Under a utilization condition of 0.15, a maximum COP of 1.85 was reached. These performance metrics are comparable with existing magnetic heat pump devices of the same scale.

The relation between the microstructure and the magnetic properties of Fe₂P-type (Mn,Fe)₂(P,Si,B) based materials has been systematically investigated by changing the annealing temperature and time. X-ray diffraction, Scanning Electron Microscopy and Energy Dispersive X-ray Spectroscopy measurements show that the alloys contain the main Fe₂P-type phase and two impurity phases of (Fe,Mn)₅Si₃-type and Fe₂MnSi-type. Boron appears to facilitate the formation of the Fe₂P-type phase during the arc-melting progress. Upon increasing the annealing temperatures from 1123 to 1423 K, the Curie temperature (T_C) decreases from 302.0 to 270.5 K in the Mn_1.15Fe_0.85P_0.55Si_0.45 alloys and the magnetic-entropy change (ΔS_M) increases linearly with annealing temperature. For the Mn_1.15Fe_0.85P_0.52Si_0.45B_0.03 alloys annealed at 1423 K for different times, T_C decreases from 263.8 and 232.8 K with increasing annealing time and ΔS_M reaches a maximum value after annealing for 48 h. The differences in the annealing temperature and time influence the Si content in the Fe₂P-type phase of the alloys and determine T_C, the thermal hysteresis and the magneto-elastic transition.