Investigation of the Solidification Pathways and Magnetic Properties of Pr 6 Fe 13 M (M = Cu, Ga, Ge) Compounds

Abstract

RE 6 Fe 13 M phases play an important role in enhancing coercivity of RE–Fe–B magnets, whereas their underlying mechanism remains unclear. Investigating the formation temperature, solidification path, and ground magnetic state of the Pr 6 Fe 13 M phase is essential for further clarifying their role in coercivity enhancement in RE 2 Fe 14 B‐based magnets. Here, Pr 6 Fe 13 M (M = Cu, Ga, Ge) alloy ingots were prepared via arc melting, and their solidification paths were determined by analyzing the as‐cast microstructures and thermal analysis. Single‐phase Pr 6 Fe 13 M samples were fabricated by melt spinning followed by rapid annealing, and their ground magnetic states were characterized. The results indicated that Pr 6 Fe 13 M (M = Cu, Ga, Ge) phases mainly form through the peritectic reaction Liquid + Fe 17 Pr 2 → Pr 6 Fe 13 M at 850, 1029, and 1188 K, respectively. Rietveld refinement confirmed that Pr 6 Fe 13 M crystallizes in the Nd 6 Fe 13 Si‐type tetragonal structure with the I 4 /mcm space group. Magnetic measurements reveal that Pr 6 Fe 13 Cu, Pr 6 Fe 13 Ga, and Pr 6 Fe 13 Ge all exhibit antiferromagnetic ordering, with Néel temperatures of 384, 391, and 383 K, respectively. Magnetic hysteresis loops measured at various temperatures consistently displayed antiferromagnetic behavior. At low temperatures, Pr 6 Fe 13 M exhibits magnetic hysteresis, which can be attributed to the magnetocrystalline anisotropy that freezes narrow domain walls and impedes magnetic moment reversal.