In this paper, the formation mechanism of amorphous phase in the Ni-Ti system was studied by means of differential scanning calorimeter (DSC), X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and magnetic analysis, etc.. The Ni/Ti coated powders were chosen to be original materials. The multi-layer metals with different original status were produced by cold rolling (CR), mechanical alloying (MA), and MA + CR. The amorphous phase transformation features were investigated during the heat treatment of these multi-layers. For the growth of amorphous layer during isothermal annealing treatment, a transient nucleation theory was utilized to deduce the relationships between the critical thickness and temperature, the critical time and temperature, the temperature-time-transformation relationship for the growth of amorphous layer during isothermal annealing treatment was also given. These relationships deduced from the above-mentioned theories were in agreement with the experiment results. The volume fraction of amorphous phase formed during isothermal annealing treatment was also calculated by means numerical value analysis method, the result was also agreeable to the experiment one. A reasonable path was proposed for the production of Ni-Ti bulk amorphous materials according to the experiment results and corresponding theoretical analyses.
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