A study on the magnetic properties of melt spun Co-Hf-Zr-B nanocomposite ribbons

Magnetic properties of melt spun Co86.5Hf11.5-xZrxB2 (x = 0-5) ribbons have been investigated. For the ribbons spun at the wheel speed of 40 m/s, hard magnetic properties with high energy product ((BH)(max)) of 34.4-52.8 kJ/m(3) and intrinsic coercivity (H-i(c)) of 176-216 kA/m were obtained for x = 0-2, but soft magnetic behavior was observed for x = 3-5 due to the appearance of the amorphous phase. By annealing the ribbons with x = 3-5, hard magnetic properties were improved arisen from the formation of magnetically hard phase. The variation of magnetic properties for Co86.5Hf11.5-xZrxB2 ribbons was correlated to microstructure change. Proper Zr substitution for Hf was helpful in refining the grain size from 10-35 nm for x = 0 to 5-15 nm for x = 1, and thus improving the magnetic properties effectively. The optimal hard magnetic properties of Co86.5Hf10.5Zr1B2 ribbons might be originated from the fine magnetically hard Co-11(Hf, Zr)(2) phase, and the exchange coupling effect among grains and/or with the face-center-cubic Co phase. (C) 2014 AIP Publishing LLC.