Solid-state amorphization behaviour in Ni/Zr multilayers with oxygen contamination

The solid-state amorphization by the interdiffusion reaction in sputter-deposited Ni-Zr multilayer films with oxygen contamination has been investigated by differential scanning calorimetry and x-ray diffractometry. Through x-ray photoelectron spectroscopy analysis, it was found that the multilayer films were contaminated with oxygen during deposition in a low-vacuum system (10-5 torr), and the concentration was modulated having the maximum in zirconium-rich regions. The kinetics of amorphization reactions has been examined by non-isothermal and isothermal annealing. Oxygen introduced into the sample during sample preparation and annealing treatments appears to affect the kinetics of the amorphization reaction associated with variation of the activation energy for interdiffusion in the amorphous layer and a critical thickness of the amorphous layer. The origins of abnormal behaviour in forming intermetallic compound as well as amorphous phase, are discussed in the context of the oxygen incorporation.