Thermal stability and nanocrystallization of Zr-Ti-Ni-Cu-Be bulk metallic glass

Abstract

The evolution of the microstructure of a Zr41.25Ti13.75Ni10Cu12.5Be22.5 (at.%) bulk metallic glass during isothermal annealing in the supercooled liquid region is studied by differential scanning calorimetry (DSC), X-ray diffraction (XRD) and transmission electron microscopy (TEM). At the annealing temperature of 383°C, the DSC trace of BMG exhibits three exothermic peaks indicating three crystallization stages. The crystallization activation energies on various crystallization stages are evaluated to be 148±10, 285±10 and 199±10 kJ/mol, respectively. The first stage crystallization of nanocrystals, recognised in DSC and TEM, probably involves icosahedral phase. In the second stage, the TEM and XRD data show the formation of Zr2Cu and ZrBe2 phases. The third stage is not yet fully characterized.