Title :
High coercivity Zr and Co substituted (Nd-Pr)-Fe-B nanophase hard magnetic alloys
Author :
Betancourt R., J.I. ; Davies, H.A.
Author_Institution :
Dept. of Eng. Mater., Sheffield Univ., UK
fDate :
7/1/2001 12:00:00 AM
Abstract :
The effects of Zr and Co substitutions for Fe on the magnetic properties of nanocrystalline near-stoichiometric (Nd0.75Pr 0.25)12(Fe1-xCox)82-z ZrzB6 (x=0,0.1,0.2 and z=0-4) alloy ribbons are reported. The nanoscale structures were derived by devitrification annealing of amorphous as-cast ribbon. Very good combinations of energy product, (BH)max (~160 kJ/m3) and intrinsic coercivities, iHc (within the range 800-1400 kA/m for various Zr concentrations) were achieved for the Co-free alloys although the Zr addition resulted in some reduction in Tc. For alloys in which, also, 10 and 20% of the Fe was substituted by Co, excellent remanence enhancement, Jr (to >1 T) were achieved with 1 at% Zr addition. Combined with excellent squareness of the J-H second quadrant, this gave (BH)max up to 175 kJ/m3, together with Curie temperatures, Tc of >375°C and >460°C for 10 and 20% Co, respectively, and with only minor reductions in iHc. The role of Zr in promoting uniform and refined grain structures and enhancing the magnetic properties will be discussed
Keywords :
Curie temperature; annealing; boron alloys; cobalt alloys; coercive force; ferromagnetic materials; iron alloys; nanostructured materials; neodymium alloys; permanent magnets; praseodymium alloys; remanence; zirconium alloys; (Nd-Pr)-Fe-B nanophase hard magnetic alloy; (Nd0.75Pr0.25)12(Fe1-xCox)82-zZrzB6; (Nd0.75Pr0.25)12(FeCoZr)82B6; Co substitution; Curie temperature; Zr substitution; devitrification annealing; energy product; grain structure; intrinsic coercivity; magnetic properties; nanocrystalline ribbon; remanence; Amorphous materials; Annealing; Cobalt alloys; Coercive force; Iron alloys; Magnetic properties; Nanostructures; Neodymium; Remanence; Zirconium;
Journal_Title :
Magnetics, IEEE Transactions on
