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Title: Hard magnetic property enhancement of Co{sub 7}Hf-based ribbons by boron doping

Hard magnetic property enhancement of melt spun Co{sub 88}Hf{sub 12} ribbons by boron doping is demonstrated. B-doping could not only remarkably enhance the magnetic properties from energy product ((BH){sub max}) of 2.6 MGOe and intrinsic coercivity ({sub i}H{sub c}) of 1.5 kOe for B-free Co{sub 88}Hf{sub 12} ribbons to (BH){sub max} = 7.7 MGOe and {sub i}H{sub c} = 3.1 kOe for Co{sub 85}Hf{sub 12}B{sub 3} ribbons but also improve the Curie temperature (T{sub C}) of 7:1 phase. The (BH){sub max} value achieved in Co{sub 85}Hf{sub 12}B{sub 3} ribbons is the highest in Co-Hf alloy ribbons ever reported, which is about 15% higher than that of Co{sub 11}Hf{sub 2}B ribbons spun at 16 m/s [M. A. McGuire, O. Rios, N. J. Ghimire, and M. Koehler, Appl. Phys. Lett. 101, 202401 (2012)]. The structural analysis confirms that B enters the orthorhombic Co{sub 7}Hf (7:1) crystal structure as interstitial atoms, forming Co{sub 7}HfB{sub x}, in the as-spun state. Yet B may diffuse out from the 7:1 phase after post-annealing, leading to the reduction of Curie temperature and the magnetic properties. The uniformly refined microstructure with B-doping results in high remanence (B{sub r}) and improves the squareness of demagnetization curve. The formation of interstitial-atom-modified Co{sub 7}HfB{sub x} phasemore » and the microstructure refinement are the main reasons to give rise to the enhancement of hard magnetic properties in the B-containing Co{sub 7}Hf-based ribbons.« less
Authors:
 [1] ; ; ;  [2] ;  [3] ; ;  [4]
  1. Department of Applied Physics, Tunghai University, Taichung 407, Taiwan (China)
  2. Department of Physics, National Chung Cheng University, Chia-Yi 621, Taiwan (China)
  3. Department of Physics, Chung-Yuan Christian University, Chungli 320, Taiwan (China)
  4. Department of Materials Science and Engineering, National Tsing Hua University, Hsinchu 300, Taiwan (China)
Publication Date:
OSTI Identifier:
22391954
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Physics Letters; Journal Volume: 105; Journal Issue: 19; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; ANNEALING; BORON; COBALT ALLOYS; COERCIVE FORCE; CRYSTAL STRUCTURE; CURIE POINT; DEMAGNETIZATION; DOPED MATERIALS; HAFNIUM ALLOYS; MAGNETIC PROPERTIES; MICROSTRUCTURE; ORTHORHOMBIC LATTICES