Microstructure evolution upon devitrification and crystallization studies of Ti-Hf-Zr-Cu-Ni-Sn-Si glassy alloy

The phase components and microstructure of as-cast Ti_41.5Cu_37.5Ni_7.5Zr_2.5Sn₅Hf₅Si₁ glass forming alloy was investigated by differential scanning calorimetry (DSC), scanning electron microscopy and in-situ neutron diffraction studies. For diameters above 3 mm the samples present small crystals identified as the Ti₅Sn₃Cu and cubic Ti(CuNi) phases. Crystallization studies in the DSC furnace and in-situ neutron diffraction reveal that the cubic titanium phase is TiNi(Cu) with the Pm-3m space group and not the β-Ti phase. The evolution of phases above T_γ show that the TiNi phase is metastable and decomposes at Tx=727 K to form the γ-TiCu phase. The Ti₅Sn₃Cu phase does not evolve in this temperature range. At room temperature by compression measurements, the alloy with 2 mm diameter shows a high failure limit of 2120 MPa with 2,1% of plasticity.