Influence of minor additions of Si on the crystallization kinetics of Cu55Hf45 metallic glasses

By means of differential scanning calorimetry the effects of minor additions of silicon on the crystallization kinetics of Cu55-xHf45Six (x = 0, 0.5, 1.0 and 2.0 at.%) alloys were studied. In the non-isothermal crystallization mode, the Kissinger method was used to obtaining the apparent activation energies of glass transition and crystallization. The highest Eg, Ex and Ep experimental values were found at 0.5 at.% of silicon i.e. Eg = 897.20 kJ/mol, Ex = 516.41 kJ/mol and Ep = 490.22 kJ/mol. In the isothermal mode, the Johnson-Mehl-Avrami model was employed in order to determine the crystallization kinetics, whilst the activation energies were analyzed with the Arrhenius equation. The results showed that addition of Si affect the relative amount of the crystallized phases. For the sample with 0.5 at.% Si content the ternary HfCuSi crystalline phase was predominant whilst for the samples with more Si, binary Cu10Hf7 and Hf Si phases were more abundant.