High performance Co80Zr15Ti3B2 melt-spun ribbons

The small substitution of Ti for Zr in the Co80Zr18B2 melt-spun ribbons resulted in a significant improvement of magnetic properties. The optimal magnetic properties of coercivity Hc = 4.5 kOe, and maximum energy product (BH)max = 5.0 MGOe were obtained in the Co80Zr15Ti3B2 ribbons produced at a wheel speed of 30 m/s. X-ray diffraction (XRD) and thermomagnetic analysis (TMA) revealed that the Co–Zr–Ti–B ribbons mainly consisted of Co11Zr2 phase and Ti substitution made the phase more unstable. The investigation of microstructure indicated that the grain size decreased significantly with the increase of Ti content. A suitable grain size of Co11Zr2 phase was believed to be the main reason for the drastic increase in coercivity. On the other hand, the appropriate refinement of grain led to a significant enhancement of intergrain exchange interaction in the Co80Zr15Ti3B2.

► The addition of Ti improved the magnetic properties of Co–Zr–B alloy significantly.
► We proved the hard magnetic phase was Co11Zr2 phase.
► The grain size decreased with the increase of Ti content.
► The refinement of grain led to the enhancement of intergrain exchange interaction.