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Titanium alloys can be fabricated by additive manufacturing techniques, which makes it possible to
produce machine components of complex geometries that would be difficult to produce by standard
methods such as machining, forming, and casting. Although titanium alloys have a high strength-to-
weight ratio, their tribological characteristics are insufficient. For this reason, ceramic coatings with
high tribological properties, e.g., PVD coatings, are frequently deposited on titanium alloys. Still, the
surface layer properties of Ti6Al4V alloy produced by the direct metal laser sintering differ from those
exhibited by this alloy when produced by the standard means in terms of microstructure, internal
stresses, texture, and porosity. In light of the above, the objective of this study was to determine the
relationship between the surface layer microstructure, morphology, and mechanical properties of the
direct metal laser sintering produced Ti6Al4V alloy and the adhesion of PVD nitride coatings. The test
samples of Ti6Al4V alloy were fabricated by two different techniques, i.e., conventional manufacturing
from wrought material (in the annealed state) and direct metal laser sintering. Two different PVD
coatings, AlTiN and TiAlN, were deposited by magnetron sputtering on a titanium substrate. Internal
stresses were measured by the X-ray diffraction and sin2(ψ) method. The microstructure was examined
by optical microscopy. Coating thickness was measured by the ball crater test. After that, coating
nanohardness was measured by the Olivier–Pharr method, and coating/substrate adhesion was assessed
by the scratch test method. The results showed that the PVD coatings deposited on the direct metal laser
sintering substrate had considerably higher adhesive properties, which resulted primarily from the better
fit of the Ecoating/Esubstrate ratio and higher compressive stresses. Scratch test results demonstrated
that all coatings deposited on the direct metal laser sintering substrate had a nearly 25% higher critical
load Lcr (which was a measure of adhesion) than the same coatings deposited on the conventionally
manufactured substrate. In addition to that, the cohesive damage mechanism was observed for the
latter.
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