Crystallization behavior and kinetics of Cu-Zr-Al-Be bulk metallic glass

The crystallization kinetics of the Cu₄₃Zr₄₃ Al₇Be₇ bulk metallic glass were studied by differential scanning calorimetry(DSC) in the continuous heating and isothermal annealing modes. Only one major peak could be detected on the DSC traces of Cu₄₃Zr₄₃ Al₇Be₇ bulk amorphous alloy, and the activation energy for crystallization corresponding to the peak determined by the Kissinger method was resulted of 239 kJ/mol. The isothermal kinetic, analyzed by the Johnson-Mehl-Avrami equation yielded values for the Avrami exponents in the range 1.69 to 2.37, which implied a crystallization governed by a three-dimensioned growth. Primary phases were essentially the cubic structure CuZr together with the Cu₁₀Zr₇ phase. At higher temperature, the CuZr disappeared while the Cu₁₀Zr₇ became predominant. After long term annealing at 731 K, the phases were Cu₁₀Zr₇, Cu₂ZrAl and Al₃Zr₅.