In the present work, the mechanical properties of the DLD-processed Ti-6Al-4V alloy were obtained by tensile tests performed at different temperatures, ranging from 20 °C to 800 °C. Thereby, the process conditions were close to the conditions used to produce large-sized structures using the DLD method, resulting in specimens having the same initial martensitic microstructure. According to the obtained stress curves, the yield strength decreases gradually by 40% when the temperature is increased to 500 °C. Similar behavior is observed for the tensile strength. However, further heating above 500 °C leads to a significant increase in the softening rate. It was found that the DLD-processed Ti-6Al-4V alloy had a Young’s modulus with higher thermal stability than conventionally processed alloys. At 500 °C, the Young’s modulus of the DLD alloy was 46% higher than that of the wrought alloy. The influence of the thermal history on the stress relaxation for the cases where 500 °C and 700 °C were the maximum temperatures was studied. It was revealed that stress relaxation processes are decisive for the formation of residual stresses at temperatures above 700 °C, which is especially important for small-sized parts produced by the DLD method. The coefficient of thermal expansion was investigated up to 1050 °C.

Additive manufacturing of titanium alloys is one of the fastest growing areas of 3D metal printing. The use of AM methods for parts production in the aviation industry is especially promising. During the deposition of products with differently sized cross-sections, the thermal history changes, which leads to non-uniformity of the structure and properties. Such heterogeneity can lead to failure of the product during operation. The structure of deposited parts, depending on the thermal cycle, may consist of α’, α + α’ + β’, and α + β in different ratios. This problem can be solved by using heat treatment (HT). This paper presents research aimed towards the determination of optimal heat treatment parameters that allows the reception of the uniform formation of properties in the after-treatment state, regardless of the initial structure and properties, using the example of a deposited Ti-6Al-4V gas turbine blade.

High-entropy alloys are a unique class of alloys with high strength and hardness, good enduring quality and corrosion resistance, as well as other attractive mechanical properties for both scientific research and practical applications. Using these unique alloys together with the dynamically developing technology of laser direct energy deposition (L-DED) carries the prospects of obtaining large-sized complex-profile products with specified increased mechanical properties. The study of the influence of L-DED parameters on the formation of high-entropy alloys will expand knowledge about the influence of temperature and cooling rate on the formation of the structure, on the mechanical characteristics of high-entropy alloys and the formation of defects and use them for thermal processes involving high-entropy alloys. Preliminary modeling will predict the phase composition of alloys in conditions of high heating and cooling rates. In the work, optimal parameters were selected for obtaining high-entropy alloys based on FeCoNiCrMn by L-DED technology. It was also shown that FeCoNiCrMn alloys were divided into areas with a high content of elements (Fe, Co, Cr) and (Mn, Ni, Cu).

High-entropy alloys (HEAs) have shown promise as materials with improved mechanical properties compared to traditional materials. Achieving the desired mechanical properties depends on the alloy composition, both in terms of percentage and elements. Laser directed energy deposition technology allows for the production of products with various complex geometries and dimensions (L-DED). It has been found that HEA FeCoNiCrCu alloys can be divided into regions with high concentrations of Fe + Co + Cr and Cu elements. Dendrite growth directions of HEA FeCoNiCrCu are (111) and (200), and the average microhardness is around 240 HV. All samples have cracks vertically along the height. Fine-grained and dendrite structures were observed. Cu-element is mainly found in cracks. The HEA FeCoNiCrCu alloy was compared with another HEA FeCoCrMnNi, successfully obtained by the same L-DED technology. Comparing the two HEAs FeCoNiCrCu and FeCoCrMnNi obtained with the same deposition parameters can help determine the impact of one element on the phase composition, microstructure and mechanical properties of the high-entropy alloy. Replacing the element Mn with Cu in HEA FeCoNiCrMn led to a shift in the dendrite growth from one to two predominant directions and a decrease in the average microhardness by 20%.