Microstructure evolution upon devitrification and crystallization studies of Ti-Hf-Zr-Cu-Ni-Sn-Si glassy alloy
Résumé
The phase components and microstructure of as-cast Ti41.5Cu37.5Ni7.5Zr2.5Sn5Hf5Si1 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 beta-Ti phase. The evolution of phases above T, show that the TiNi phase is metastable and decomposes at Tx=727 K to form the gamma-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.