Abstract:Titanium nitride thin films deposited by reactive dc magnetron sputtering under various substrate bias voltages have been investigated by X-ray diffraction. TiN thin films exhibits lattice parameter anisotropy for all bias voltages. Preferential entrapment of argon atoms in TiN lattice has been identified as the major cause of lattice parameter anisotropy. Bombardment of argon ions during film growth has produced stacking faults on {111} planes of TiN crystal. Stacking fault probability increases with increasing substrate bias voltages. X-ray diffraction line profile analysis indicates strain anisotropy in TiN thin films. Diffraction stress analysis by d-sin 2 ψ method reveals pronounced curvature in the plot of interplanar spacing (d) (or corresponding lattice parameter (a)) versus sin 2 ψ. Direction dependent elastic grain interaction has been considered as possible source of the observed anisotropic line broadening. IntroductionTitanium nitride (TiN) thin films deposited by reactive magnetron sputtering is widely used for improving the hardness and wear resistance of materials surfaces [1]. Such functional properties critically depend on the microstructure of TiN thin films. It is well known that ion bombardment during thin film deposition can change the microstructure of such hard coating [2][3][4]. During the films deposition, the substrate is negatively biased (with respect to deposition chamber) so that the positively charged ions of the sputtering gas such as argon can be accelerated towards the substrate during the film growth. Negative bias voltage of the substrate can be varied in order to change the energy of the bombarding ions which is the key to change the film microstructure. In the present work, microstructure of TiN thin films deposited at various substrate bias voltages has been studied by X-ray diffraction. Intrinsic/growth stresses and crystallographic textures in TiN films have been studied as a function of substrate bias voltages (i.e. energies of the bombarding ions). Specimen preparation and characterizationPolycrystalline titanium nitride thin films (thickness ~ 2µm for all films) were deposited on silicon ({100} Si) substrate by planer reactive dc magnetron (magnetron power ~ 270W) sputtering under various substrate bias voltages (0kV to -5kV) using a high voltage pulsed DC power supply. The sputter target was 99.99% pure titanium and argon gas of high purity (99.99%) was used as the sputtering gas for the magnetron targets. For the reactive deposition of titanium nitride, the reactive gas nitrogen was introduced. Operating pressure of the sputtering chamber was 3x10

Despite numerous investigations in the past, mechanism of cementite dissolution has still remained a matter of debate. The present work investigates cementite dissolution during cold wire drawing of pearlitic steel (~ 0.8wt% carbon) at medium drawing strain (up to true strain 1.4) and the role of dislocations in the ferrite matrix on the dissolution process. Quantitative phase analysis using x-ray diffraction (XRD) confirms more than 50% dissolution of cementite phase at drawing strain ~ 1.4. Detail analysis of the broadening of ferrite diffraction lines confirms presence of strain anisotropy in ferrite due to high density of dislocations (~ 1015m-2) at drawing strain 1.4. The results of the analysis shows that the screw dislocations near the ferrite-cementite interface are predominantly responsible for pulling the carbon atoms out of the cementite phase leading to its dissolution.