Nanostructural studies of PVD TiAlB coatings

Abstract

TiAlB coatings with different compositions were deposited by co-sputtering from TiAl and TiB2 targets onto AISI316 stainless steel substrates at a temperature of 170 °C. The stoichiometry and nanostructure have been studied by X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and transmission electron microscopy (TEM). Analysis of the XPS spectra suggests the presence of phases in agreement with the equilibrium Ti-Al-B phase diagram. Diffraction studies (XRD and TEM) indicate that coatings with B/Al ratios <6 are amorphous, while coatings with B/Al ratios >6 exhibit a nanocomposite structure with average TiB2 grain sizes of ∼2-3 nm for the highest B/Al ratio of 16. Nanocomposite coatings show significantly improved H/E ratios that are beneficial for protecting soft steels and light alloys. Copyright © 2006 John Wiley & Sons, Ltd.