Microstructural and thermoanalytical investigations of nano-phase formation in Ti20Zr20Cu60 alloy

The kinetics of crystallization of Ti20Zr20Cu60 amorphous alloy has been investigated from room temperature to 773K using differential scanning calorimetry (DSC). The thermogram exhibits two-stage crystallization in this alloy. The values of activation energy of crystallization for the two steps using Kissinger equation are 423.8 and 314.7kJ/mol respectively. On annealing the specimen to a temperature just before the glass transition temperature, primary crystallization is observed to occur with Cu2Ti orthorhombic and CuZr cubic metastable phases. Further, annealing the specimen to a temperature just below the onset of crystallization obtained from DSC thermogram, tetragonal CuTi3 and cubic Cu5Zr equilibrium phases were found to form as observed from the selected area electron diffraction (SAED) pattern in TEM. Presence of some unidentified d-lines indicated the formation of a metastable Laves phase namely Zr2TiCu3.