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

Highlights: • Crystallization kinetics are studied by means of isothermal and non-isothermal heating. • The small additions of Si shifted the glass transition and crystallization events to higher temperatures. • The activation energy reached its maximum values at 0.5 at.% of Si and then tended to decrease. - Abstract: By means of differential scanning calorimetry the effects of minor additions of silicon on the crystallization kinetics of Cu_55-xHf₄₅Si_x (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 E_g, E_x and E_p experimental values were found at 0.5 at.% of silicon i.e. E_g = 897.20 kJ/mol, E_x = 516.41 kJ/mol and E_p = 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.