In this study, corrosion and wear behavior of three kinds of coatings by two processes, namely, plasma electrolytic oxidation (PEO) coatings (Ti/TiO₂), gas nitriding coating (Ti/TiN), and the duplex coating (Ti/TiO₂-N) by combination of PEO and gas nitriding methods were systematically investigated. X-ray diffraction tests, field-emission scanning electron microscopy, and adhesion tests are employed for the coating characterization, along with the wear and electrochemical test for evaluating the corrosion and tribological properties. The morphology and structure of the coating consist of micro-cavities known as the pancake structure on the surface. The electrolytic plasma oxidation process produces a typical annealing behavior with a low friction coefficient based on the wear test. The coating consists of nitride and nitrate/oxides titanium for nitrided samples. The surface morphology of nitrided oxide titanium coating shows a slight change in the size of the crystals and the diameter of the cavities due to the influence of nitrogen in the titanium oxide coating. The tribological behavior of the coatings showed that the wear resistance of the duplex coating (Ti/TiO₂-N) and Ti/TiO₂ coatings is significantly higher compared to Ti/TiN coatings and uncoated Ti samples. The polarization resistance of the Ti/TiO₂-N and Ti/TiO₂ coatings was 632.2 and 1451.9 kΩ cm², respectively. These values are considerably greater than that of the uncoated Ti (135.9 kΩ cm²). Likewise, impedance showed that the Ti/TiO₂-N and Ti/TiO₂ coatings demonstrate higher charge transfer resistance than that of other samples due to better insulating behavior and denser structure.

A new generation of Oxide Dispersion Strengthened (ODS) alloys called Oxide Precipitation Hardened (OPH) alloys, has recently been developed by the authors. The excellent mechanical properties can be improved by optimizing the chemical composition in combination with heat treatment. However, the behavior of such materials requires the consideration of a large number of variables, nonlinearities, and uncertainties in the analyses, and the modeling of such alloys by analytical methods is not accurate enough. Therefore, artificial intelligence (AI) methods, such as machine learning (ML), can be beneficial to alleviate the problems associated with the complexity of these alloys. In this work, three different hybrid ML techniques have been employed to estimate the ultimate tensile strength (UTS) and elongation in these special alloys. The proposed methods include a feedforward artificial neural network (FF-ANN) trained using particle swarm optimization (PSO) and two adaptive neuro-fuzzy inference system (ANFIS) methods trained using both fuzzy C-means (FCM) clustering and subtractive clustering (SC). Since OPH alloys are mainly produced via mechanical alloying (MA) of a mixture of powder components followed by consolidation and hot rolling, a series of standard tensile tests were performed on the different variants of the OPH alloy. In this way, some critical parameters such as UTS and elongation could be extracted from the experimental results. The main contribution of the present study is to estimate these important parameters based on some material properties including Aluminum (Al), Molybdenum (Mo), Iron (Fe), Chromium (Cr), Tantalum (Ta), Yttrium (Y) and Oxygen (O), MA and the heat treatment conditions. The results show that the proposed strategies are not only able to accurately determine the complex behavior of OPH alloy with an accuracy of about 95%, but they can also help the designer to benefit from these powerful tools to design new versions of such materials without analytical calculations.

Thin nanocrystalline amorphous NiTi film was deposited on Si substrate using DC magnetron sputtering. The as-deposited NiTi thin film was crystallized by heat treatment at 500 °C for 1 h. The crystal structure, surface morphology, microstructure and surface chemistry of the deposited films were studied using X-ray diffraction, atomic force microscopy, scanning electron microscopy and X-ray photoelectron spectroscopy (XPS), respectively. Corrosion behaviour was assessed in Ringer’s solution at 37 °C by open circuit potential (OCP), potentiodynamic polarization and electrochemical impedance spectroscopy as a function of exposure time. OCP values indicate that the tendency for the formation of a spontaneous oxide film is greater for the NiTi thin films than the bulk NiTi. Long time exposure to Ringer’s solution was found to have a great effect on the corrosion behaviour of the samples. Significantly low corrosion current density was obtained for the annealed NiTi film from the potentiodynamic polarization curves indicating a typical passive behaviour, but as-deposited film and bulk NiTi alloy exhibited breakdown of passivity at potentials approximately +1.4 V (vs. SCE). XPS showed that the oxide film formed on the annealed NiTi thin film mainly composed of Ti oxides, and no evidence of Ni was found up to 8.2 nm beneath the top surface, suggesting the excellent corrosion resistance of this sample in Ringer’s solution.