In a PACVD system, titanium alloys were exposed to inductive radio-frequency (RF) plasmas of H-2+N-2 and Ar+BCl3+H-2+N-2 gas mixtures for their nitriding and boron nitride respectively. Hard nanocomposite thin films of RAIN and TiAlBN were formed on Ti-6Al-4V alloys in an inductive RE plasma of Ar+H-2+N-2 and Ar+3.5 vol.% of BCl3+H-2+N-2, respectively. The substrates were grounded, i.e., self-biased, during plasma thin film formation for 30 min each. TiAlBN was deposited by sputtering in a reactive PVD system. A quadrupole mass spectrometer (QMS) sampled the plasma at a constant distance of 0.5 cm from the sample surface in real time. The mass species (m/e) at 0.5 cm were recorded during the deposition process. To separate the particles reaching the substrate surface from those leaving it, the narrocomposite thin films coated samples of Ti alloys were introduced in an RF plasma of Ar+H-2 mixture without the presence of N-2 and BCl3 and negatively biased up to V-b = -350 V The QMS at 0.5 cm measures the etched and sputtered species from the surface of the coated samples. Comparing the QMS results between the grounded samples with the monomers in the RF plasma and the negatively biased voltage samples without monomers in the Ar+H-2 plasma the net plasma surface interactions (PSI) were evaluated. The behavior of the coating process of nanocomposite thin films of TiAlN and TiAlBN on the Ti alloy samples is strongly dependent on the plasma surface phenomena. (C) 2007 Elsevier B.V. All rights reserved.