The mechanical properties, structure, and morphology of milled and 3D-printed Ti-6Al-4V alloys produced by selective laser melting were investigated in this study. The mechanical properties were investigated by means of nanoindentation, a tensile test, and a three-point bending test. An Atomic Force Microscope (AFM) was used to study the surface topography and roughness of both titanium alloys. The surface structure and phase analyses were studied by a scanning electron microscope (SEM) and through powder X-ray diffraction (XRD). The results from the nanoindentation experiments showed that the 3D-printed sample has higher indentation hardness and modulus than the milled one. The AFM observation of the surface topography of the samples showed that the milled sample has a higher roughness than the 3D-printed one. The tensile test results showed that the 3D-printed sample by means of Selective Laser Melting (SLM) technology has about 26% higher tensile strength and smaller elongation than the milled one. The three-point bending test revealed that the 3D-printed Ti-6Al-4V sample has higher flexural strength than the milled one. It was found that the 3D-printed sample has a smaller crystal size than the milled one, which, according to the Hall–Petch relationship, leads to its higher indentation hardness.

Important from exploitation point of view mechanical properties of single-layer, double-layer, and mixed alumina and ceria films and their stainless steel (SS) substrate were investigated by means of nanoindentation experiments. As a result, we obtained the experimental load–displacement curves and calculated the indentation hardness (H_IT) and indentation modulus (E_IT), by means of Oliver and Pharr approximation method. Numerical simulations of the process of nanoindentation by means of finite element method were performed as well, in order to obtain more information about the plastic properties of the investigated films. The obtained results show that the mixed Al₂O₃+Ce₂O₃ film, obtained at dominant concentration of cerium ions in the working electrolyte, has the highest indentation hardness and modulus, followed by the single Ce₂O₃-CeO₂ film, the mixed Al₂O₃+Ce₂O₃ film, obtained at dominant concentration of aluminum ions in the working electrolyte, the double Ce₂O₃-CeO₂/Al₂O₃ layer, and single Al₂O₃ layer.