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

Authors

• Bhaskar Das, University of Nebraska-LincolnFollow
• Balamurugan Balasubramanian, University of Nebraska-LincolnFollow
• Pankaj Kumar, School of Basic Sciences, Indian Institute of Technology, Mandi 175 001, India
• Ralph A. Skomski, University of Nebraska-LincolnFollow
• Shah R. Valloppilly, University of Nebraska-LincolnFollow
• Jeffrey E. Shield, University of Nebraska-LincolnFollow
• Arti Kashyap, School of Basic Sciences, Indian Institute of Technology, Mandi 175 001, IndiaFollow
• David J. Sellmyer, University of Nebraska-LincolnFollow

Document Type

Article

Date of this Version

2013

Citation

IEEE TRANSACTIONS ON MAGNETICS, VOL. 49, NO. 7, JULY 2013

Comments

© 2013 IEEE

Abstract

This study presents the structural and magnetic properties of melt-spun HfCo₇, HfCo_7-xFe_x (0.25 < x < 1), and HfCo₇Si_x (0.2 < x < 1.2) alloys. Appreciable permanent-magnet properties with a magnetocrystalline anisotropy of about 9.6–16.5 Mergs/cm³, a magnetic polarization J_s = 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 A, b = 4.278 A, and c = 8.070 A. 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.