Microstructural and thermoanalytical investigations of nano-phase formation in Ti_(20)Zr_(20)Cu_(60) alloy

摘要

The kinetics of crystallization of Ti_(20)Zr_(20)Cu_(60) amorphous alloy has been investigated from room temperature to 773 K 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 314.7 kJ/mol respectively. On annealing the specimen to a temperature just before the glass transition temperature, primary crystallization is observed to occur with Cu_2Ti orthorhombic and CuZr cubic metastable phases. Further, annealing the specimen to a temperature just below the onset of crystallization obtained from DSC thermogram, tetragonal CuTi_3 and cubic Cu_5Zr 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 Zr_2TiCu_3.