Early stages of interface reactions between AlN and Ti thin films

Abstract

The early stages of interface reactions between AlN and Ti thin films were investigated using x-ray diffractions, Auger electron spectroscopy, cross section transmission electron microscopy (XTEM), and high resolution XTEM. The AlN/Ti bilayers were deposited on a molybdenum substrate using reactive and nonreactive magnetron sputtering techniques. After deposition, the bilayers were heat treated for 1–10 h at 600 °C in a nitrogen atmosphere. Decomposition of the AlN layer took place at the AlN/Ti interface and its products, Al and N, reacted with Ti to produce a AlN/Al3Ti/Ti2N/Ti3Al/α-(Ti, Al)ss phase sequence. This phase sequence is not consistent with the Ti–Al–N phase diagram and is believed to be the outcome of the particular conditions that prevail in the thin film and correspond to a particular set of kinetic parameters. A model that explains the development of the phase sequence and predicts its evolution after prolonged heat treatments is put forward. The applicability of such a solid-state reaction technique for producing functionally graded coating for wear and corrosion resistance applications is discussed.