Microstructure and magnetic properties of nanocrystalline cobalt-zirconium boride alloy prepared by melt spinning and subsequent annealing

The structural, thermal and magnetic characteristics of cobalt-zirconium boride (Co80Zr18B2) alloy were investigated in this work. In this regards, cobalt-zirconium boride samples with different structures and crystallite sizes were prepared using a copper boat vacuum induction melting plus melt-spinning and subsequent annealing processes. Prepared samples were characterized using X-ray diffraction, field emission scanning electron microscopy, differential scanning calorimetry and vibrating sample magnetometer. According to X-ray diffraction results, cobalt--zirconium (Zr2Co11) single phase can successfully form by means of a melt-spinning process at a wheel speed of 40ms(-1). The saturation magnetization and coercivity of this sample are 58emu/g and 3 kOe, respectively, which exhibit a hard magnetic property. Cobalt-zirconium compound which formed during melt-spinning process was not stable and transformed to Co23Zr6 during annealing process up to 500 degrees C. The maximum value of coercivity (H-c=3.4 kOe vs. 3 kOe for single Zr2Co11 phase) is related to cobalt-zirconium boride alloy after annealing at 500 degrees C for 1h.