摘要
Bulk metallic glass composites (BMGCs) reinforced by micro- (spherical size of about 10 gin) and nano-sized (20-50 nm) A13Zr crystals were synthesized by copper mold suction casting method. The isothermal crystallization of Cu4oZr44AgsAls BMGCs in the super- cooled liquid region was studied by differential scanning calorimeter (DSC), X-ray diffractometer (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The mechanisms for nucleation and growth of the crystalline phases precipitated in two-stage crystallization process and the effect of the isothermal treatment on the in situ crystalline phases were discussed. Results show that the BMGCs experience a primary crys- tallization process. Nano-sized A13Zr and Cul0Zr7 phases precipitate from the amorphous matrix successively. Fur- thermore, isothermal annealing has no effect on the pre- existing particles in the as-cast sample, which creates a new method to synthesize BMGCs strengthened by duplex crystalline phases with a large size difference. And the reinforced phase could also be dominated with intention if the as-cast BMGCs preparation and isothermal treatment process can be controlled more accurately.
Bulk metallic glass composites (BMGCs) reinforced by micro- (spherical size of about 10 gin) and nano-sized (20-50 nm) A13Zr crystals were synthesized by copper mold suction casting method. The isothermal crystallization of Cu4oZr44AgsAls BMGCs in the super- cooled liquid region was studied by differential scanning calorimeter (DSC), X-ray diffractometer (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The mechanisms for nucleation and growth of the crystalline phases precipitated in two-stage crystallization process and the effect of the isothermal treatment on the in situ crystalline phases were discussed. Results show that the BMGCs experience a primary crys- tallization process. Nano-sized A13Zr and Cul0Zr7 phases precipitate from the amorphous matrix successively. Fur- thermore, isothermal annealing has no effect on the pre- existing particles in the as-cast sample, which creates a new method to synthesize BMGCs strengthened by duplex crystalline phases with a large size difference. And the reinforced phase could also be dominated with intention if the as-cast BMGCs preparation and isothermal treatment process can be controlled more accurately.
基金
financially supported by the National Natural Science Foundation of China (Nos.51061008 and 50961008)