Wire arc additive manufacturing (AM) is able to replace the traditional manufacturing processes of Ti alloys. At the same time, the common drawback of Ti workpieces produced by AM via wire deposition welding is the formation of a coarse-grained dendritic structure, its strong anisotropy and, consequently, lower strength as compared to a monolithic alloy. In this work, a new method is proposed for the enhancement of the strength properties of the Ti-6Al-4V alloy synthesized by AM via wire deposition welding, which involves the use of a wire with an initial ultrafine-grained (UFG) structure. The UFG wire is characterized by a large number of defects of the crystalline lattice and grain boundaries, which will enable increasing the number of “crystallization centers” of the α-phase, leading to its refinement. The macro- and microstructure, phase composition and microhardness of the Ti-6Al-4V alloy samples were investigated. The microhardness of the alloy produced by layer-by-layer deposition welding using a UFG wire was shown to be on average 20% higher than that of the samples produced by a deposition welding using a conventional wire. The nature of this phenomenon is discussed, as well as the prospects of increasing the mechanical characteristics of Ti alloys produced by additive manufacturing.

Titanium alloys are widely used in various industries. The most common and well-known titanium alloy is titanium alloy with aluminum and vanadium (Ti-6Al-4V). This alloy is used, for example, in the manufacture of aircraft engines. As part of the development of technologies and the emergence of the evolving requirements for materials, Ti-6Al-4V alloys with ultrafine grains less than 1 μm may become promising. This modification of the alloy has excellent strength characteristics, such as increased fatigue resistance. However, manufacturers are aware of the machinability problem of titanium alloys. To date, a sufficiently high level of understanding of this problem has already been achieved. But, there is practically no information about the machinability of ultrafine-grained alloys and their comparison, in this regard, with the usual coarse-grained version. This study presents the results of experimental studies on the influence of cutting parameters (cutting speed, V, m/min; feed rate, Fz, mm/rev) on the roughness and microstructure of the surface of Ti-6Al-4V samples with coarse-grained and ultrafine-grained structures produced via equal-channel angular pressing. It is shown that turning at a low cutting speed (V = 48 m/min) results in a better surface roughness, Ra, for the coarse-grained sample compared to its ultrafine-grained alloy counterpart. When the cutting speed is increased by 1.5 times (up to V = 72 m/min), on the contrary, the ultrafine-grained sample has a lower surface roughness, Ra, compared to the coarse-grained sample. The differences in the morphology and microstructure of the chips, depending on the microstructure type of the processed alloy, are discussed: the presence of plastic flow lines in the chip microstructure of the turned ultrafine-grained sample and the formation of shear bands, cleavages, and microcracks in the chips of the turned coarse-grained alloy.

The manufacturing of personalized implants from Ti–6Al–4V alloy using additive manufacturing technologies is a promising direction in modern medicine. However, components produced by these methods are characterized by a non-equilibrium microstructure, high residual stresses, and anisotropy of mechanical properties, which necessitates subsequent heat treatment. The aim of the present work was a systematic comparative study of the effect of three heat treatment regimes—stress relief annealing (600 °C, 3 h), subtransus annealing in the (α + β) region (950 °C, 1 h, furnace cooling), and solution treatment followed by aging (STA: 950 °C, 0.5 h, water quenching + aging at 675 °C, 3 h)—on the microstructure and mechanical properties of Ti–6Al–4V alloy manufactured by laser powder bed fusion (L-PBF) and plasma arc directed energy deposition (PA-DED). The microstructure was examined using scanning electron microscopy, transmission electron microscopy, and electron backscatter diffraction (EBSD). Tensile mechanical properties were determined in two directions: parallel and perpendicular to the build direction. Stress-relief annealing led to an increase in the ductility of the alloy without a noticeable decrease in strength and without significant changes in the microstructure. Subtransus annealing resulted in the formation of an equilibrium lamellar (α + β) structure, which provided a substantial increase in ductility with a moderate decrease in strength. Solution treatment and aging resulted in formation of a bimodal microstructure. Subtransus annealing (both alloys), STA (L-PBF) and stress relief annealing (PA-DED) provided properties comparable to those of wrought material. The obtained results form the basis for a scientifically informed selection of both the manufacturing route and the heat treatment regime for biomedical implants made of Ti–6Al–4V alloy.

Background and Objectives: Currently, the development of local drug delivery systems for the treatment of cancer patients is a pressing issue. Such systems allow for the targeted delivery of anticancer drugs directly to the tumor site, ensuring prolonged drug release or reducing the risk of recurrence after tumor removal, minimizing the impact on healthy tissues and thereby reducing the overall toxic load on the body. This work is devoted to evaluating the prospects of using scaffolds based on low-modulus titanium Ti-15Mo alloy with a biomimetic coating as a platform for the local administration of the cytostatic drug cisplatin into the patient’s body. Methods: Porous coatings were obtained by plasma electrolytic oxidation in an aqueous solution of sodium phosphate and calcium acetate with the addition of various components. The influence of coating parameters on the corrosion resistance of samples and on the antiproliferative effect of cisplatin-loaded scaffolds was evaluated. Human K562 hemoblastosis, HT116 intestinal cancer, and SKOV3 ovarian cancer cell lines were used as cell models. Results: It was shown that the addition of sodium phosphate (the PS type electrolyte) provides the formation of a coating with a developed system of interconnected pores characterized by an attractive combination of parameters: high porosity (17%), high pore size (3.9 μm), and considerable thickness (17.4 μm). This coating demonstrated the best corrosion resistance in a Ringer solution as compared to the other tested states. In addition, the PS coating loaded with cisplatin exhibited a pronounced cytotoxic effect on cancer cells. This effect was attributed to its ability to fix cisplatin on the surface, which slows down its release into the extracellular environment, increasing the time of its action, thereby contributing to a more effective (by more than 3 times) suppression of tumor cell proliferation compared to the action of the standard form of the drug in the form of a solution when changing the growth medium and subsequent incubation for 48 h. Conclusions: PS scaffolds made of low-modulus titanium alloy Ti-15Mo with a biomimetic surface in an electrolyte based on an aqueous solution of sodium phosphate and calcium acetate with the addition of sodium silicate can be used as an advanced platform for the local delivery of the cytostatic drug cisplatin, which makes them promising for application in orthopedic oncology.