HfCo7-Based Rare-Earth-Free Permanent-Magnet Alloys

• Published in: IEEE transactions on magnetics Vol. 49; no. 7; pp. 3330 - 3333
• Main Authors: DAS, B, BALAMURUGAN, B, KUMAR, Pankaj, SKOMSKI, R, SHAH, V. R, SHIELD, J. E, KASHYAP, A, SELLMYER, D. J
• Format: Conference Proceeding Journal Article
• Language: English
• Published: New York, NY Institute of Electrical and Electronics Engineers 01-07-2013
• Subjects: Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; Materials science; Other topics in materials science; Physics; Magnetic anisotropy; Doping; Rare earth alloys; Permanent magnets; magnetocrystalline anisotropy; rare-earth-free alloys; Magnetic properties
• ISSN: 0018-9464; 1941-0069
• DOI: 10.1109/TMAG.2013.2242856

This study presents the structural and magnetic properties of melt-spun HfCo7, HfCo7-xFex (0.25 <= x <=), and HfCo7Six (0.2 <= x <= 1.2) alloys. Appreciable permanent-magnet properties with a magnetocrystalline anisotropy of about 9.6-16.5, Mergs/cm(3), a magnetic polarization J(s) approximate to 7.2-10.6 kG, and coercivities H-c = 0.5-3.0 kOe were obtained by varying the composition of these alloys. Structural analysis reveals that the positions of x-ray diffraction peaks of HfCo7 show good agreement with those corresponding to an orthorhombic structure having lattice parameters of about a = 4.719 angstrom, b = 4.278 angstrom, and c = 8.070 angstrom. Based on these results, a model crystal structure for HfCo7 is developed and used to estimate the magnetic properties of HfCo7 using density-functional calculations, which agree with the experimental results.