Formation and crystallization of Zr-Ni-Ti metallic glass

The metallic Zr65Ni25Ti10（mole fraction, %） glass has been fabricated by a single roller melt-spinning method. The glass forming ability（GFA） and thermal stability of the Zr65Ni25Ti10 melt-spun ribbons were investigated by using X-ray diffraction（XRD） and differential scanning calorimetry（DSC） in the mode of continuous heating. It is shown that the reduced glass transition temperature (Trg) is 0.506 and the supercooled liquid region （ΔTx） is 30 K. Two exothermic peaks were observed in the DSC curves of the as-quenched ribbon, which indicates that the crystallization process undergoes two different stages. The phase transformation during the isothermal annealing was investigated by X-ray diffraction（XRD） and transmission electronic microscope（TEM）. It is observed that the metastable FCC Zr2Ni（Fd3m, a=12.27 ） precipitated while annealing in the suppercooled region（615 K） and the stable BCT Zr2Ni（I4/mcm, a=6.499 , c=5.270 ） precipitated while annealing at higher temperature（673 K or 723 K）. The crystallines are on nanoscale, with grain size of 1530 nm. The reason for the precipitation of the different structural Zr2Ni from the glassy matrix under different annealing conditions was discussed based on the concept of multi-component chemical short range order（MCSRO）.