HRTEM Analysis of Magnetron Sputtered Ni₄Al Thin Films

Abstract

The nanostructural characteristics of direct-current magnetron sputter-deposited Ni4Al alloy films were studied during in situ isothermal annealing in a transmission electron microscope (TEM). An expansion of the lattice by nearly 5% was observed for the synthesized films in their low-thickness and as-deposited state. The lattice size approaches the bulk value when the film thickness increases or after vacuum annealing heat-treatment. The Ni4Al films have a nanocrystalline structure in which the ordered L12 phase appears upon annealing at above 500°C. A grain coalescence trend was found for the Ni4Al films during the in situ annealing above 500°C. This can be the main reason for the abnormal grain growth of these films at these high temperatures.