Substantial diffusion of Zr during solid-state amorphization in Ni/Zr multilayers

Abstract

To examine the proposed model that amorphization is achieved by the motion of one species only, Ni/Zr multilayers have been prepared by sputter deposition at a pressure of 1 Pa. The as-deposited specimen shows the planar and sharp interface between Ni and Zr layers. The amorphous phase is clearly observed at the residual Ni layers and around the void edge in the Zr layer from the cross-sectional TEM images of the samples annealed at 300 ‡C for 1 h. Composition analysis verifies that considerable Zr diffusion occurs through the grain boundary in the Ni layer during the annealing. The activation energy for amorphization is determined to be 1.17 eV per atom through a Kissinger-type analysis. This paper clearly shows the formation of amorphous NiZr alloys when Zr diffusion is comparable to Ni diffusion.