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In this work, the corrosion behavior of titanium composites of titanium-titanium boride composites for marine applications was investigated by conducting electrochemical polarization experiments in...

The present research evaluates different weight percentages of nano-B4C incorporated into Ti-6Al-4V through a powder metallurgy technique. Nano-B4C weight percentage was set at 0 %, 5 %, and 10 % with a particle size of ≤100 nm. Cylindrical preforms with different initial preform densities were prepared using a suitable die and punch assembly. Further, the preforms were sintered in a muffle furnace with argon atmosphere at a temperature of 1 100 °C for a holding period of 1 hr. Cold deformation experiments were carried out using a 1 000 kN hydraulic press; incremental loading steps of 5 kN were applied on the preform until the first visible cracks appeared on the free surfaces. The experimental results have shown that the powder metallurgy composite with 10 % nano-B4C demonstrates higher densification properties such as axial stress, axial strain, hoop stress, hydrostatic stress, and Poisson's ratio.

In this work grain boundary (GB) wetting phase transition of Inconel 718 is investigated. 15% GBs are totally wetted when the temperature is raised to 1200 °C. GB was characterized using Electron Backscattering Diffraction (EBSD). The experimental results revealed that the wetted GB fraction increases to 80% at 1200 °C and no evidence of transformation beyond this limit. The GBs clearly show that the wetting state and the cooling rate at about 1200 °C are almost similar to that of quenching. Under ambient condition, it exhibits low ductility which leads to the formation of second phase and increase in hardness and decrease of tensile strength.

Performance of elevated temperature grain refinement and texture analysis are investigated in the temperature range of 500 °C, 600 °C, 700 °C and 800 °C in this study. Electron Back Scattered Diffraction (EBSD) was used for observation of grain distribution of Inconel 718. Tensile test was performed for all the heat treated samples and the fractrographic was examined using Scanning Electron Microscope (SEM). In addition, the texture of Inconel 718 was examined using crystallographic textures and Orientation Distribution Function (ODF) plots. The results indicate that Inconel 718 heat treated with 800 °C shows better grain refinement and provide optimum texture. Furthermore, it also indicated that decreased grain size contributed to the decreased cleavage size that leads to increased ductility.

The electrolytic ZnO based alloy coating with admixed interfacial blend of Mg have been successfully coated on medium carbon steel (AISI 4140) substrate by spray coating technique over a range of applied current density and dwell time. The structural and morphological properties of the coated samples are characterized using Optical Microscope (OM), Scanning Electron Microscope (SEM), X-ray Diffraction Analysis (XRD) and Energy Dispersive Spectroscopy (EDS) analysis. The adhesion test was carried out using scratch testing. The corrosion behavior is evaluated in a chloride environment (NaCl) by Tafel exploration as a function of coating thickness. The results revealed that the introduction of ZnO-Mg particles increases the adhesion strength of the AISI 4140. During scratching, cracks parallel with the scratch channel, external transverse cracks, adhesive spalling, and complete breaking of the coating within the scratch channel were observed. The acquired results exhibit that the introduction of ZnO - Mg coating improves corrosion resistance of AISI 4140 in NaCl solution. Equally, deposition thickness significantly affected the adhesion and corrosion properties. Increasing the coating thickness from 30 µm to 90 µm leads to decreasing the adhesion and corrosion properties.

In this paper, two titanium–titanium boride composites aiming at 20 % and 40 % (by volume) of titanium boride reinforcement were processed through spark plasma sintering. The mechanical properties such as fracture toughness, indentation creep, contact stiffness, indentation hardness and Young's modulus of the processed composites were evaluated by means of nano-indentation. The Young's modulus, indentation hardness and contact stiffness increase with the increase in volume fraction of titanium boride, while the fracture toughness and indentation creep decrease. The titanium composite with 38.5 % (by volume) titanium boride showed improved mechanical properties compared to the composite with 24 % (by volume) titanium boride reinforcement. The morphological influence of TiB reinforcement on the mechanical properties was also discussed.