This paper is devoted to using multi-pass friction stir processing (FSP) for admixing 1.5 to 30 vol.% copper powders into an AA5056 matrix for the in situ fabrication of a composite alloy reinforced by Al-Cu intermetallic compounds (IMC). Macrostructurally inhomogeneous stir zones have been obtained after the first FSP passes, the homogeneity of which was improved with the following FSP passes. As a result of stirring the plasticized AA5056, the initial copper particle agglomerates were compacted into large copper particles, which were then simultaneously saturated by aluminum. Microstructural investigations showed that various phases such as α-Al(Cu), α-Cu(Al) solid solutions, Cu₃Al and CuAl IMCs, as well as both S and S’-Al₂CuMg precipitates have been detected in the AA5056/Cu stir zone, depending upon the concentration of copper and the number of FSP passes. The number of IMCs increased with the number of FSP passes, enhancing microhardness by 50–55%. The effect of multipass FSP on tensile strength, yield stress and strain-to-fracture was analyzed.

This work studied the possibility of producing multimaterials consisting of aluminum bronze CuAl₉Mn₂ and nickel-based superalloy Inconel 625 by double-wire electron beam additive manufacturing. Samples with 5%, 15%, 25%, and 50% of the nickel-based alloy in aluminum bronze were produced for the research. The structural features of these multimaterials were analyzed, and tensile properties, microhardness, and dry sliding friction properties were measured. The results showed that 50% of the nickel-based alloy in the multimaterial composition provides the formation of a dendritic structure. Such a material shows worse values of ductility and wear resistance. Samples containing 5%, 15%, and 25% of Inconel 625 provide similar friction coefficient values, whereas, with increasing concentration of the nickel-based alloy, the material’s ultimate tensile strength and microhardness increase significantly.

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.

Friction stir processing of additive workpieces in the sample growth direction (the vertical direction) and the layer deposition direction (the horizontal one) was carried out. The hardening regularities of aluminum-silicon alloy A04130 and aluminum-magnesium alloy AA5056 manufactured by electron beam additive technology were studied. For each material, 1 to 4 subsequent tool passes were performed in both cases. It was found that the formation of the stir zone macro-structure does not significantly change with the processing direction relative to the layer deposition direction in additive manufacturing. The average grain size in the stir zone after the fourth pass for AA5056 alloy in the horizontal direction was 2.5 ± 0.8 μm, for the vertical one, 1.6 ± 0.5 μm. While for the alloy A04130, the grain size was 2.6 ± 1.0 μm and 1.8 ± 0.7 for the horizontal and vertical directions, respectively. The fine-grained metal of the stir zone for each alloy in different directions had higher microhardness values than the base metal. The tensile strength of the processed metal was significantly higher than that of the additively manufactured material of the corresponding alloy. The number of tool passes along the processing line is different for the two selected alloys. The second, third and fourth passes have the most significant effect on the mechanical properties of the aluminum-magnesium alloy.

AA5154 aluminum alloy wall was built using EBAM where the wall’s top layers were alloyed by depositing and then remelting a Mo powder-bed with simultaneous transfer of aluminum alloy from the AA5154 wire. The powder-beds with different concentrations of Mo such as 0.3, 0.6, 0.9 and 1.2 g/layer were used to obtain composite AA5154/Mo samples. All samples were characterized by inhomogeneous structures composed of as-deposited AA5154 matrix with coarse unreacted Mo articles and intermetallic compounds (IMC) such as Al₁₂Mo, Al₅Mo, Al₈Mo₃, Al₁₈Mg₃Mo₂ which formed in the vicinity of these Mo particles. The IMC content increased with the Mo powder-bed concentrations. The AA5154 matrix grains away from the Mo particles contained Al-Fe grain boundary precipitates. Mo-rich regions in the 0.3, 0.6, 0.9 and 1.2 g/layer Mo samples had maximum microhardness at the level of 2300, 2600, 11,500 and 9000 GPa, respectively. Sliding pin-on-steel disk test showed that wear of A5154/Mo composite reduced as compared to that of as-deposited AA5154 due to composite structure, higher microhardness as a well as tribooxidation of Al/Mo IMCs and generation of mechanically mixed layers containing low shear strength Mo₈O₂₃ and Al₂(MoO₄)₃ oxides.

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.