Research Of Co-Cu-B Amorphous Alloys Powder Preparation And Crystallization

In this paper, the Co-Cu-B nano-amorphous alloy powders were obtained by the way that the aqueous solution of NaBH₄ was added in the mixing aqueous solution CoCl₂·6H₂O and CuCl₂·2H₂O, made use of BH₄^-restore out Co²⁺ and Cu²⁺ from CoCl₂·6H₂O and CuCl₂·2H₂O aqueous blending solution. The compositions, constructions, magnetic properties and crystallization kinetics of the powders were analyzed by X-ray diffraction(XRD), inductively coupled plasma-atomic emission spectroscopy(ICP), X-ray Photoelectron Spectroscopy(XPS), transmission electron microscope(TEM), selective area electronic diffraction (SAED), differential scanning calorimetry (DSC), and vibrating sample magnetometer(VSM), and researched the crystallization mechanism of amorphous powderWhen compare mole outcome between Co and Cu is greater than 9.08, amorphous form Co-Cu-B nanometer alloy powder is obtained. Co-Cu-B nano-amorphous alloy powder pellet assumes sphere, grain diameter between 20 - 50 nm.DSC curves of amorphous form Co-Cu-B nanometer alloy powder only have one exothermal peak, and it is confirmed that crystallization happened in single-step. The phase component is different between Co_65.65Cu_7.23B_27.12 and Co_64.27Cu_6.37B_29.36 after non-isothermal crystallization.The vibrating sample magnetometer study of Co-Cu-B nano-amorphous alloy powders showed that the saturation magnetization and coercivity increased with greater Co/Cu compare mole. After crystallization, the saturation magnetization and coercivity of Co_65.65Cu_7.23B_27.12 increased. The saturation magnetization of Co_64.27Cu_6.37B_29.36 increased and the coercivity of it decreased. The coercivity between 125.6 Oe and 164.4Oe, it was different from normal Co-based amorphous alloy which always have excellent soft magnetic properties.It can be conclude from Surinach fitting that the non-isothermal mechanism of Co-Cu-B nano-amorphous alloy powder is JMA model, which is different from block shape amorphous alloy. Avrami index n decrease from 1.3 to 0.8, nucleation ratio is zero in entire process, may be the reason is that there are plenty of aggregate atom cluster in prepared amorphous sample, which compose the base of crystal growth, crystal growth on the base of it, surpass nucleation process. Crystal growth mechanism is mainly prestore nucleation growth way that controlled by diffuse.