Multilayer nitride coatings provide some of the best performance when in their use for the production of metalworking tools. In this work, vacuum-arc plasma-assisted deposited multilayer ZrN/CrN coatings with different numbers of constituent layers were characterized for high-temperature oxidization in air using weighing, confocal and scanning electron microscopy and synchrotron XRD. Oxidizing at 300 °C did not deteriorate the coating surfaces, while higher temperatures caused surface deterioration and oxidation accompanied by cracking, delamination and considerable mass gains. The coating with higher number of thinner layers showed higher oxidation resistance due to more prominent oxygen barrier effect.

The importance of taking into account directional solidification of grains formed during 3D printing is determined by a substantial influence of their crystallographic orientation on the mechanical properties of a loaded material. This issue is studied in the present study using molecular dynamics simulations. The compression of an FCC single crystal of aluminum bronze was performed along the axis. A Ni single crystal, which is characterized by higher stacking fault energy (SFE) than aluminum bronze, was also considered. It was found that the first dislocations started to move earlier in the material with lower SFE, in which the slip of two Shockley partials was observed. In the case of the material with higher SFE, the slip of a full dislocation occurred via successive splitting of its segments into partial dislocations. Regardless of the SFE value, the deformation was primarily occurred by means of the formation of dislocation complexes involved stair-rod dislocations and partial dislocations on adjacent slip planes. Hardening and softening segments of the calculated stress–strain curve were shown to correspond to the periods of hindering of dislocations at dislocation pileups and dislocation movement between them. The simulation results well agree with the experimental findings.

Introduction. Modern technologies allow the synthesis of nanostructured coatings from multiple chemical elements to combine different physical, mechanical, and chemical properties in one coating. Promising in this respect are coatings formed via layer-by-layer deposition of zirconium and chromium nitrides. The deposition of various chemical elements on various substrates requires separate studies in order to produce high-strength and wear-resistant coatings. The purpose of this work is to study the structural-phase state and mechanical properties of ZrCrN coatings formed by plasma-assisted vacuum arc evaporation. Materials and methods. The investigation is performed on specimens comprising VK8 hard alloy substrates with zirconium and chromium nitride coatings as well as with multilayer ZrCrN coatings. The methods used are confocal laser scanning microscopy, X-ray diffraction analysis, high-resolution scanning electron microscopy, nanoindentation, and scratching. Results and discussion. The experimental results obtained showed that the mode of multilayer ZrCrN coating evaporation greatly affects the structure, morphology, surface roughness, and mechanical properties of the coatings. In particular, by varying the substrate rotation speed during coating deposition it is possible to control the deposition time of each coating layer and thereby modify the layer properties. Conclusions. The investigation results showed that variation of the evaporation conditions allows one to obtain a ZrCrN coating with a high nanohardness of 45 GPa on a VK8 alloy substrate. Analysis of mechanical test results indicate good adhesion between the studied coatings and the substrate. Scratch tests revealed that fracture of CrN and ZrN coatings occurs by the cohesive mechanism, and the surface of ZrCrN coatings exhibits uniform scratches without any signs of fracture. Based on the results obtained, ZrCrN-2…ZrCrN-4 coatings can be recommended for use as hard and wear-resistant coatings.

When working out 3D building-up modes, it is necessary to predict the material properties of the resulting products. For this purpose, the crystallography of aluminum bronze grains after electron beam melting has been studied by EBSD analysis methods. To estimate the possibility of sample form changes by pressure treatment, we simulated structural changes by the method of molecular dynamics during deformation by compression of individual grains of established growth orientations. The analysis was carried out for free lateral faces and grain deformation in confined conditions. Simulation and experiments on single crystals with free lateral faces revealed the occurrence of stepwise deformation in different parts of the crystal and its division into deformation domains. Each domain is characterized by a shear along a certain slip system with the maximum Schmidt factor. Blocking the shear towards the lateral faces leads to selectivity of the shear along the slip systems that provide the required shape change. Based on the simulation results, the relationship between stress–strain curves and structural characteristics is traced. A higher degree of strain hardening and a higher density of defects were found upon deformation in confined conditions. The deformation of the columnar grains of the built material occurs agreed with the systems with the maximum Schmidt factor.