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Heat resistant cobalt-based alloys have found a specific niche in the present-day mechanical engineering due to their unique properties. To begin with, cobalt-based alloys are used as corrosion, heat and wear resistant materials intended for aggressive environments and operation at extreme temperatures, e.g. blades, nozzles, swirlers, rings and other elements of turbines and internal combustion engines. Traditional molding methods applied in the mechanical engineering fail to provide necessary operational and technological characteristics of aforementioned machine parts. Owing to selective laser melting it is possible to reduce a production time and manufacturing costs for machine elements with a complex physical configuration and generate an alloy with an extraordinary structure, which is not found in traditionally combined compounds. A structure of cobalt exists in two crystal modifications: a hexagonal close-packed epsilon phase, a low-temperature phase and a face-centered cubic lattice gamma phase, a high-temperature phase. The alloy hardness is directly related to an amount of a low-temperature phase. The laser melting shortens a laser beam impact time on a powder composition due to a higher power and laser travelling speed. A high value of heat conductivity seems to be the reason for rapid solidification and cooling, which, in their turn, increase a percent of an alpha-martensite phase in an alloy and improve the hardness and wear resistance of machine parts. The reported paper summarizes studies aimed at the development of a stable phase structure three-component alloy (Сo-66 mass % Cr-6 mass % Mo) based on the cobalt-chromium-molybdenum system and mixed up via selective laser melting.

Biodegradable materials are currently attracting the attention of scientists as materials for implants in reconstructive medicine. At the same time, ceramics based on calcium silicates are promising materials for bone recovery, because Ca2+ and Si2+ ions are necessary for the mineralization process, and they take an active part in the formation of apatite. In the presented research, the protective silicate biocoatings on a Mg0.8Ca alloy were formed by means of the micro-arc oxidation method, and the study of their morphology, structure, phase composition, corrosion, and biological properties was carried out. Elongated crystals and pores were uniformly distributed over the surface of the coatings. The coated samples exhibited remarkable anti-corrosion properties in comparison with bare magnesium alloy because their corrosion current decreased 10 times, and their corrosion resistance increased almost 100 times. The coatings did not significantly affect the viability of the cells, even without the additional dilution of the extract, and were non-toxic according to ISO 10993-5: 2009. In this case, there was a significant difference in toxicity of the pure Mg0.8Ca alloy and the coated samples. Thus, the results demonstrated that the applied coatings significantly reduced the toxicity of the alloy.

The additive manufacturing of low elastic modulus alloys that have a certain level of porosity for biomedical needs is a growing area of research. Here, we show the results of manufacturing of porous and dense samples by a laser powder bed fusion (LPBF) of Ti-Nb alloy, using two distinctive fusion strategies. The nanostructured Ti-Nb alloy powders were produced by mechanical alloying and have a nanostructured state with nanosized grains up to 90 nm. The manufactured porous samples have pronounced open porosity and advanced roughness, contrary to dense samples with a relatively smooth surface profile. The structure of both types of samples after LPBF is formed by uniaxial grains having micro- and nanosized features. The inner structure of the porous samples is comprised of an open interconnected system of pores. The volume fraction of isolated porosity is 2 vol. % and the total porosity is 20 vol. %. Cell viability was assessed in vitro for 3 and 7 days using the MG63 cell line. With longer culture periods, cells showed an increased cell density over the entire surface of a porous Ti-Nb sample. Both types of samples are not cytotoxic and could be used for further in vivo studies.

Porosity, values of nanohardness and Young’s modulus of the specimens obtained with the method of selective laser melting were measured with optical methods, scanning electron microscopy and Nano Hardness Tester NHT-S-AX-000X device for measuring physicomechanical properties. Ti-45wt%Nb powder obtained with mechanical alloying was used for selective laser melting. The results have shown that increased heat input due to the laser power growth up to 80 W and scanning speed decrease down to 40 mm/s decreases the porosity of the specimen. The nanohardness average value is not sensitive to the changes of scanning modes in the investigated range. The Young’s modulus decreases with energy input increase.

In this work, we study the effect of RF magnetron oblique angle deposition (OAD) on morphology, structure, and elemental composition of as-deposited and heat-treated Cu containing calcium phosphates. The control over the surface morphology and nano roughness provided by OAD is of great interest as both Mesenchymal Stem Cells and various types of bacteria respond strongly to nanoscale topography. A Cu substituted hydroxyapatite target was used to deposit coatings on the surface of titanium (Ti) and silicon (Si) substrates. The samples were placed at an oblique angle of 80° relative to the surface of the sample holder and in a normal configuration with respect to the flux direction and, therefore, parallel to the target. The dense homogeneous coatings with globular surface features deposited at normal flux incidence (NFI) configuration changed to elliptical, highly oriented structures with the direction dictated by the atomic shadowing effect when the substrate was deposited at an oblique angle. As-deposited thin films were subjected to post-deposition-heat-treatment at 700 °C in an Ar atmosphere. This led to a drastic change in the surface morphology and, namely, lost the directionality of the nanostructures. According to the X-ray diffraction data, the samples deposited obliquely showed preferential growth in the (002) plane and lower internal stress, than samples coated at NFI for both the Si and Ti substrates. The RMS roughness of the films deposited obliquely on Si was twice that of the films deposited at NFI (860 ± 80 pm and 408 ± 60 pm, respectively). However, it was not the case for the Ti substrate, the RMS roughness decreased from 42 ± 4 nm for coatings deposited at normal flux geometry to 33 ± 2 nm for coatings deposited obliquely. The heat-treatment of the samples deposited at 80° resulted in a significant increase in the surface roughness: 8 ± 0.7 nm for Si and 71 ± 4 nm for Ti substrates. The obtained results demonstrate that the oblique angle deposition can be used to fabricate nano-rough surface morphologies.