The Nd-Fe-Rh system: Phase relations determination at 600 ℃ and magnetic property measurement of related compounds

The isothermal section of the Nd-Fe-Rh system at 600 ℃ was constructed based on the phase identification and analysis results from annealed alloys using X-ray diffraction and Scanning electron microscopy equipped with Energy dispersive spectroscopy. Two previously reported binary compounds, Nd4Rh and Fe2Nd, could not be confirmed. No new ternary compounds were found in the isothermal section. In the present work, the homogeneity ranges of the Fe-Rh binary system were redefined using phase disappear method, which were determined to be about 70–100 Fe at%, 51–69 Fe at%, 0–45 Fe at% for the single-phase region α-Fe, FeRh and γ-(Rh, Fe), respectively. It was confirmed that the maximum solid solubility of Fe in NdRh2, Nd3Rh and Nd7Rh3 is about 15.6 at% Fe, 4.0 at% Fe and 3.1 at% Fe, respectively, while no appreciable solubility was observed for the other binary compounds in the Nd-Fe-Rh system. The isothermal section of the Nd-Fe-Rh ternary system at 600 ℃ consists of 13 single-phase regions, 23 two-phase regions, and 11 three-phase regions. It suggests the presence of predominant antiferromagnetic exchange interaction in the NdRh compound. For the 38Nd-8Fe-54Rh sample, two magnetic entropy change peaks originate from the combined contribution from two magnetic phase transitions, an antiferromagnetic-paramagnetic transition and a ferromagnetic-paramagnetic transition for NdRh and NdRh2 phase, respectively. •The isothermal section of the Nd-Fe-Rh system at 600 ℃ was constructed.•The effect of Fe-solution on magnetic properties of Nd33.3Rh66.7-xFex (x=0, 6, 12, 18) was investigated.•The magnetic ground state and magnetic phase transition of NdRh were obtained.•A wide temperature span (about 94 K) for magnetic refrigeration in 38Nd-8Fe-54Rh alloy were observed that greatly enlarges the RC value.