Solid state amorphization reactions in Ni/Ti multilayer composites prepared by cold rolling

Solid state amorphizations in mechanically deformed Ni/Ti multilayer composites have been investigated by differential scanning calorimetry and X-ray diffraction. The growth of amorphous alloy in our Ni/Ti composites was facilitated by the large number of grain boundaries and relatively large degree of disorder induced in the metal layers by the cold rolling. The formation of different products of solid-state reaction in the Ni/Ti composites has been elucidated in terms of magnetic and enthalpy analysis. It is thought that the solid state amorphization occurs first during heating, followed by the formation of intermetallic compounds through direct solid-state reaction of elemental nickel and titanium and by the crystallization of the amorphous alloy already formed by the solid state amorphization reaction. The values of the activation energy for interdiffusion and interdiffusion coefficient for the formation of amorphous alloy in the Ni/Ti composites have also been calculated.