Effects of W substitution on the magnetic properties, phase evolution and microstructure of rapidly quenched Co80Zr18B2 alloy

Abstract The effects of a partial substitution of W for Zr on the magnetic properties, phase evolution, and microstructure of Co 80 Zr 18− x W x B 2 ( x =0, 1, 2 and 3) melt-spun ribbons are investigated in this paper. For the as-spun samples, the optimal magnetic properties of i H c =6.6 kOe and ( BH ) max =4.5 MGOe are achieved in the Co 80 Zr 16 W 2 B 2 . Thermomagnetic analysis (TMA) and x-ray diffraction (XRD) results suggest that the as-spun Co 80 Zr 16 W 2 B 2 mainly comprises of hard magnetic phase. Scanning electron microscope (SEM) results indicate that W addition refines the microstructure, which results in an increase in the intergrain exchange interaction. The effects of heat treatment on the magnetic properties of as-spun Co 80 Zr 18− x W x B 2 ( x =0, 1, 2 and 3) are also studied. The maximum i H c of 7.3 kOe with a ( BH ) max of 3.8 MGOe is obtained in the Co 80 Zr 16 W 2 B 2 after a heat treatment at 550 °C. The origin of coercivity enhancement in Co 80 Zr 16 W 2 B 2 is ascribed to the increase in magnetocrystalline anisotropy field ( H a ) of hard magnetic phase.