An anomaly in martensitic transformation (the effect of martensitic two-peak splitting in the temperature-dependent thermal expansion coefficient) in complex alloyed 12% chromium steels Fe-12%Cr-Ni-Mo-W-Nb-V-B (ChS-139), Fe-12%Cr-Mo-W-Si-Nb-V (EP-823) and Fe-12%Cr-2%W-V-Ta-B (EK-181) was investigated in this study. This effect is manifested in steels with a higher degree of alloying (ChS-139). During varying temperature regimes in dilatometric analysis, it was found that the splitting of the martensitic peak was associated with the superposition of two martensitic transformations of austenite depleted and enriched with alloying elements. The anomaly was subsequently eliminated by homogenization of the steel composition due to high-temperature aging in the γ-region. It was shown that if steel is heated to 900 °C, which lies in the (α + γ) phase region or slightly higher during cooling, then the decomposition of austenite proceeds in two stages: during the first stage, austenite is diffused into ferrite with carbides; during the second stage, shear transformation of austenite to martensite occurs.

The mechanical properties of a heat-resistant aluminum alloy Al-5.5%Ce-5.8%Fe-1.1%Ni-0.7%Zr fabricated by L-PBF were investigated under static and cyclic loading, considering the influence of build orientation and surface condition of the specimens. Moreover, deformation-induced microstructural changes in the alloy were analyzed. It was established that surface machining has little effect on the alloy’s strength but enhances its ductility, fatigue strength, and fatigue. The build orientation was found to affect ductility—samples fabricated in the horizontal direction exhibited approximately twice the plasticity compared to those built vertically, while strength characteristics and fatigue life remained nearly unchanged. During deformation, the following structural changes were observed: a pore-enriched zone formed near the fracture surface; the melt pools were elongated along the direction of the applied load; fine intermetallic inclusions of Al₉FeNi, Al₄Ce, and Al₃Zr phases formed during L-PBF partially dissolved in the solid solution; the lattice parameter of the aluminum solid solution decreased, presumably due to the dissolution of Ni and Fe atoms; and the broadening of diffraction peaks of the aluminum solid solution increased.

The study analyzes the effect of laser power and velocity on the structural phase state and properties of complex-alloyed titanium alloy VT23 (Ti–Al–V–Mo–Cr–Fe) obtained by direct laser deposition. VT23 titanium alloy has a unique combination of strength, corrosion resistance, and biocompatibility, which makes it in demand in the aerospace and medical industries. However, traditional manufacturing methods (casting, stamping) often fail to provide the required accuracy and quality of complex parts. In this work, X-ray phase analysis and optical metallography revealed that the deposited samples consist of α- and β-phases (~20 % β-phase) with a typical “basket weave” structure. In macrostructure of the obtained samples, thermal bands and interlayer boundaries were recorded, the formation of which is associated with the peculiarities of crystallization process during direct laser deposition. The results of optical metallography showed that microstructure of the deposited material combines large columnar crystals in the overlap areas of two adjacent layers, as well as small equiaxed grains. Despite this distribution of structural components, the microhardness (~488 HV _0.2 ) remains homogeneous throughout the deposited samples in both the laser scanning and sample deposition directions. The results confirm that direct laser deposition can be used to produce VT23 titanium alloy parts with a controlled microstructure. Optimization of the process parameters of direct laser deposition minimizes the probability of defect formation and provides stable mechanical properties, which opens prospects for application of the technology in the production of critical parts.

The structural features of the Fe-17%Cr-12%NI-2%Mo-0.02%C alloy manufactured by selective laser melting (SLM) and the thermal stability of the formed structures are investigated. It is shown that crystallization cells form at SLM, the boundaries of which are volume plexes of dislocations, fixed by segregation of impurity atoms. The microhardness of such a structure is one and a half times higher than that of an alloy of the same composition in a standard hardened state. During annealing up to 800 °C, this cellular structure maintains stability while maintaining hardness indices.

The features of the structure formed during selective laser melting (SLM) on the example of austenitic steel Fe-17%Cr-12%Ni-0.02%C (316L) and nickel alloy Ni-11%Cr-5%Co-6%Al-3%Ti-4%Mo-5%W-0.16%C-0.02%B are considered in this work. The structure formation occurs under conditions of ultrafast cooling rates from the region of the melt during laser treatment and subsequent thermal cycling during solidification of material adjacent regions. The following structural features are considered: hierarchical structure, heterogeneity of the alloying elements distribution, dislocation structure, macrostresses and crystallographic texture.