Effect of yttrium addition on the non-isothermal crystallization kinetics and fragility of Cu-Zr-Al bulk metallic glass

Bulk metallic glasses with the composition of Cu43Zr48Al9 and (Cu43Zr48Al9)98Y2 were prepared by copper mold casting technique in this paper. X-ray diffraction (XRD) and differential scanning calorimetry (DSC) were used to investigate their structure and non-isothermal crystallization kinetics. The results show that the influence of heating rate on crystallization is larger than that on glass transition. The crystallization process of (Cu43Zr48Al9)98Y2 is more sensitive to heating rate than that of Cu43Zr48Al9. Due to Yttrium addition, the glass transition and nucleation process for crystallization become easier, while the grain growth process for crystallization become more difficult based on the activation energies. The Avrami exponents of (Cu43Zr48Al9)98Y2 decrease at low heating rates, which is totally different from that of Cu43Zr48Al9. These two bulk metallic glasses should be considered as “Intermediately fragile glass formers” according to their fragility indices.