Study on microstructure and crystallization kinetics of Zr₄₆Cu₄₆Al₈ amorphous alloys prepared by copper mold absorption casting and high energy ball milling

The Zr₄₆Cu₄₆Al₈ bulk amorphous alloys in the diameter of 3 mm were prepared by copper mold absorption casting, and a series of alloy powders in different particle sizes were obtained by high-energy ball milling. The effects of preparation methods on the microstructure and crystallization kinetics of amorphous alloys were studied by X-ray diffraction, differential scanning calorimeter, scanning electron microscope, and typical thermodynamic calculation methods. The results show that, the complete amorphous structure can be obtained in bulk alloys and alloy powders. The glass transition and crystallization of bulk amorphous alloys show the obvious dynamic effects. The best parameters for the preparation of amorphous powders by single factor variable method are the milling speed as 300 r·min^-1, the ball-to-powder weight ratio as 30:1, and the ball milling time as 15 h. In the same conditions, except for the supercooled liquid region, the thermodynamic parameters of bulk amorphous alloys are generally higher than those of the amorphous powders, and the crystallization heat in bulk amorphous alloys is more intense. With the increase of heating rate, the thermodynamic parameters of these two alloys move to the high temperature region, and at the same time, the width of supercooled liquid region increases gradually. The apparent activation energy values at the characteristic temperatures of these two alloys are similar, and the bulk alloys show the higher apparent activation energy values and the better thermal stability.