The growth of amorphous phase and the formation of competing intermetallic compounds in mechanically deformed Ni/Ti multilayered composites have been investigated by X-ray diffraction, scanning electron microscopy, transmission electron micrography, and magnetic measurement. Experimental observations in the Ni/Ti system have been performed, supporting a transient nucleation model for solid-state amorphization. The amorphous layers in the Ni/Ti multilayered composites continue to grow until they have attained a temperature-dependent critical thickness or a temperature-dependent critical annealing time. The relationships between the critical amorphous layer thickness and temperature, between the critical annealing time and temperature, and between the annealing conditions (temperature, time) and amorphization transformation, have been deduced and compared with the experimental results. The quantitative relationships can give a direction for the bulk amorphization in the Ni/Ti multilayered composites.