Recycling of titanium alloys represents a modern and economically attractive processing route, as it enables a significant reduction in production costs associated with the high price of titanium. However, the properties of recycled β-titanium alloys have not yet been sufficiently investigated in the scientific literature, and their potential for processing by additive manufacturing technologies remains largely unexplored. This study focuses on evaluating the recycling of Ti-15Mo and Ti-13Nb-13Zr alloys using the horizontal plasma arc melting (HPAM) method and further examines subsequent processing steps, including hot working to the required shape for atomisation and subsequent powder processing via the LPBF technique. In all technological stages, the microstructure was characterised, chemical analysis was performed, and, where applicable, mechanical properties were evaluated. The results demonstrate that recycling of the investigated alloys is feasible, as is their subsequent processing up to the production of additively manufactured specimens. Nevertheless, strict control of the oxygen content is critical for both alloys, as the current levels exceed the limits specified by the relevant standards. At such elevated oxygen concentrations, the alloys are unsuitable for biomedical applications; however, their use in structural applications remains realistic, particularly considering the production cost reduction achieved through the implementation of recycling.

Directed energy deposition enables efficient fabrication of complex Ti-6Al-4V components, yet process-induced microstructural gradients and porosity across the build height remain poorly understood with respect to their effects on mechanical and fatigue performance. In this study, we investigate the relationships between directed energy deposition process parameters, the resulting microstructure, and anisotropic mechanical behavior. The study expands the current understanding of directed energy deposition-processed Ti-6Al-4V by providing a detailed analysis of microstructural evolution in both build directions and presenting new insights into fatigue properties. The microstructural and mechanical characteristics of the alloy are systematically described with an emphasis on their mutual relationship. The material exhibited a predominantly α’ martensitic microstructure, with no significant variation in phase fraction as a function of distance from the build platform, consistent with the measured hardness. Electron backscatter diffraction analysis did not reveal a pronounced crystallographic texture, whereas transmission electron microscopy observations identified deformation twins within the α’ phase. Porosity was mainly oriented perpendicular to the build direction. The combination of a martensitic microstructure and the presence of pores resulted in low ductility. Under cyclic loading, pores acted as crack initiation sites, while their planar orientation limited their effect on crack propagation, indicating that the mechanical response was governed primarily by the martensitic microstructure rather than pore-assisted crack growth. Overall, the results highlight the critical role of microstructure and inherent defects in controlling the mechanical behavior of additively manufactured components and provide a basis for process optimization and post-processing strategies such as heat treatment or hot isostatic pressing.

PurposeMetal implants have a significantly higher elastic modulus than bone, which can lead to difficult osseointegration. One way to adapt them is to use porous structures, but these can lead to an increase in the corrosion rate and the release of increased amounts of metal species into the human body. The purpose of this article is to study the kinetics of Ti species dissolution into the human body.Design/methodology/approachThis work focused on the spontaneous release of Ti species from a 3D printed gyroid structure of the beta alloy TiNb25Ta4Sn8. The dissolution kinetics were monitored by exposure tests in a physiological saline solution environment with the addition of fluoride (PSF) and minimum essential medium (MEM) followed by Ti determination by electrothermal atomic absorption spectrometry (ET-AAS).FindingsThe dissolution rate from the low-grade passive layer in the fluoride environment is controlled by cathodic oxygen reduction. In a fluoride-free environment, the quality of the passive layer is high and dissolution is not dependent on the oxygen content in the environment. Numeric simulations confirmed a sufficient rate of Ti excretion from the bloodstream. The corrosion rate is sufficiently low (215 nm.a-1) even in the more aggressive fluoride-containing environment and does not compromise the mechanical properties and functionality of the implant for a lifetime of 30 a.Originality/valueThis work dealt a novel beta alloy TiNb25Ta4Sn8 using processing by modern 3D printing technology into a gyroid structure, which provides the most isotropic mechanical properties of all porous structures.

Composite materials with Ti or Ti alloy reinforcement in a Zn matrix are new, promising materials with potential applications in implantology. Infiltrating zinc into the porous titanium reinforcement of a designed implant could improve its osseointegration. In this field, it is important to avoid the formation of brittle intermetallics; therefore, understanding their growth is fundamental. This work focuses on characterizing the Ti-Zn intermetallic phases at the interface of the TiAlV/Zn and Ti/Zn composites. Samples were prepared by immersing the Ti-6Al-4V or Ti bulk material in zinc melt at various temperatures. After various dwell times, the samples (pieces of Ti-6Al-4V or Ti in the molten zinc) were removed from the furnace and cooled in air. The sequence of evolution of intermetallic phases was observed to be dependent on dwell time at selected temperatures. The influences of surface treatment methods on the boundary structure were also tested.

The Ti-6Al-4V alloy is highly desired for use in the biomedical and aerospace industries, but components produced using laser powder bed fusion (LPBF) often require post-processing to meet the strict surface quality and mechanical requirements of these industries. This study investigates the influence of laser surface treatment under different protective atmospheres (air, argon, and nitrogen) on the microstructure, mechanical, tribological, and biological properties of Ti-6Al-4V alloy previously produced by LPBF. A continuous-wave laser (200 W, 1070 nm) was used to remelt the surfaces of as-printed samples. Comprehensive characterization was performed using XRD, XPS, Raman spectroscopy, SEM/EDS, hardness testing, tribological measurements, and in-vitro cytotoxicity assays. The laser-treated samples exhibited a significant transformation of the surface microstructure from martensitic α′-Ti to a fine α + β phase mixture, along with the formation of hard compounds such as titanium oxides and nitrides. The depth of the remelted layer varied depending on the processing atmosphere, with the deepest and hardest layer observed for samples treated in air. All laser treatments substantially enhanced surface microhardness and dry sliding wear resistance compared to untreated samples. The most favorable combination of low friction, minimal wear, and surface uniformity was achieved with the argon-treated sample. In-vitro tests confirmed that all treated surfaces remained non-cytotoxic, supporting their potential for biomedical applications.

Cobalt-based alloys are widely used for orthopedic implants due to their excellent mechanical properties and corrosion resistance. Biomedical Co-Cr-Mo alloy, commonly applied in knee replacements, is typically produced by precision casting. However, in cases requiring patient-specific geometries, additive manufacturing technologies, such as Selective Laser Melting (SLM), offer promising alternatives. This study compares the microstructure and mechanical properties of Co-Cr-Mo alloy in the as-cast state and after SLM processing. The SLM-produced samples exhibited a fine, cellular microstructure and superior mechanical strength. Specifically, the printed alloy achieved a yield strength of 688 +/- 8 MPa and an ultimate tensile strength of 994 +/- 11 MPa, exceeding that of the cast material by about 495 +/- 1 MPa. These results demonstrate the potential of SLM technology for manufacturing customized orthopedic implants with improved mechanical properties and dimensional accuracy.

Optimising the mechanical properties required for biomedical applications is something that porous Ti-6Al-4V structures offer the opportunity to do. Triply periodic minimal surface (TPMS) structures, such as the Diamond and Gyroid structures, provide interconnected pores that can be used to adjust strength, stiffness and deformation. The mechanical behaviour of these two architectures under compressive and bending loads is compared in this study, with the use of additively manufactured samples. The results demonstrate that pore geometry significantly impacts mechanical behaviour. Diamond structures exhibit higher stiffness and strength, whereas Gyroid structures provide a more isotropic and flexible response. These findings emphasise the importance of architecture when designing implants and other components for which optimised mechanical properties and geometry are essential.

The development of multifunctional surfaces on titanium implants is a critical strategy for mitigating post-operative infections and enhancing long-term clinical integration. This study investigates a dual-stage surface modification of the Ti6Al4V alloy, combining shifted Laser Surface Texturing (sLST) with functional ethanol-based silver coatings. The novelty of this research lies in the synergistic combination of advanced sLST surface engineering, which creates a hexagonal "reservoir" topography, and the stable functionalization of these complex structures with antimicrobial silver particles. Initially, the substrates were laser-processed to create a defined hexagonal surface morphology, followed by the deposition of silver-containing) and silver-free coatings via dip-coating and subsequent heat treatment. Comprehensive surface characterization confirmed a homogeneous distribution of silver particles within the porous laser-textured structure, with silver concentrations in the resulting extracts reaching several mg/l. Biological evaluation revealed that the silver-doped coatings achieved nearly 100% antibacterial efficacy against Escherichia coli after 24 hours, showing zero or only negligible colony growth compared to the silver-free and reference samples. Cytotoxicity testing with extracts using L929 fibroblasts demonstrated that all modified surfaces maintained relative metabolic activity above 70% threshold, thus qualifying as non-toxic according to ISO 10993-5 standards. Despite this high metabolic viability, microscopic analysis revealed localized impairments in cell morphology, suggesting a complex cellular response that may be influenced by preparation-related factors. The integration of sLST texturing with Ag-doped ethanol coatings represents a highly effective approach for producing antimicrobial titanium surfaces with maintained cytocompatibility, offering significant potential for advanced orthopaedic and dental applications.

This study investigates the influence of different manufacturing routes on the corrosion behaviour of the Ti-25Nb-4Ta-8Sn beta titanium alloy produced by casting, powder metallurgy, and additive manufacturing using selective laser melting. The objective is to elucidate the relationship between microstructure and corrosion resistance in environments relevant to biomedical and dental applications, including simulated body fluids and fluoride-containing solutions. The selectively laser melted samples were intentionally fabricated using processing parameters chosen to promote increased porosity and defect formation to simulate a worst‑case scenario; these features are not inherent to optimised SLM Ti‑25Nb‑4Ta‑8Sn alloys. Consequently, the additively manufactured samples exhibited characteristic microstructural features such as melt pools, partially fused particles, crevices, and interconnected porosity, which influenced their corrosion behaviour. Corrosion performance was evaluated using electrochemical techniques, including open circuit potential measurements, potentiodynamic polarisation, and electrochemical impedance spectroscopy. The selectively laser melted alloy showed higher susceptibility to localised corrosion in neutral environments; however, under aggressive fluoride-containing conditions, it exhibited improved corrosion resistance due to the formation of a more stable and protective passive layer. The corrosion current density in fluoride media was approximately 20 µA/cm2 for cast alloy and 2 µA/cm2 for printed material. In contrast, the cast and powder metallurgy samples displayed comparable corrosion resistance, with only minor differences under aggressive conditions. The novelty of this work lies in the systematic comparison of corrosion mechanisms across multiple fabrication routes, explicitly accounting for defect-promoting additive manufacturing conditions relevant to realistic biomedical service environments.

The present work focuses on the fatigue behaviour of the additively manufactured Ti6Al4V-ELI alloy, which is mainly used for biomedical applications such as implants and prosthetics. It was found that the studied material is characterised by an almost fully dense (relative density higher than 99.97%) microstructure, which consists of needle-like α-Ti lamellae with β-Ti phase on their boundaries. Fatigue tests showed that the lifespan of the Ti6Al4V-ELI alloy produced by laser powder bed fusion within the stress amplitude of 300–400 MPa lies in the range of 106–107 cycles. Scanning electron microscope fractographic images showed that the surface of the studied material plays the most important role in determining the material’s lifetime. The findings of this study contribute to a deeper understanding of the structure–property relationships in terms of extremely damaging fully reversible (tension-compression) fatigue measurements in additively manufactured Ti6Al4V-ELI and support the development of more reliable biomedical components, especially hip joint prostheses.

Laser powder bed fusion (LPBF) enables the production of Ti-6Al-4V alloys with tailored porous structures, which are beneficial for biomedical applications due to their reduced elastic modulus and enhanced bone integration potential. This study examines the effect of hot isostatic pressing (HIP) on the microstructure and mechanical properties of diamond and gyroid porous structures fabricated by LPBF. Solid tensile specimens served as reference materials. HIP significantly reduced porosity, decreased ultimate tensile strength and hardness, but markedly increased ductility (from 6% to 17%). Compressive strengths reached approximately 100 MPa (diamond) and 240 MPa (gyroid), with HIP causing only a slight increase in strain. However, HIP notably improved bending performance, raising the flexural strength of gyroid structures from 280 MPa (as-printed) to 340 MPa (post-HIP). The strength of LPBF-fabricated Ti-6Al-4V porous structures is reduced by HIP, but their ductility and bending performance are enhanced, making them more suitable for biomedical applications.

The Mg-Y-Zn magnesium alloy system is known for the presence of Long-Period Stacking Ordered (LPSO) phases that improves strength and ductility with minimal amounts of alloying elements. Even better improvements are associated with the specific microstructure known as the Mille-Feuille (MF) structure that can occur in this alloy as well after proper heat treatment. This study systematically compares the traditional ingot metallurgy method with the Bridgman method (slow cooling), coupled with diverse heat treatments and extrusion process. Microscopic analyses reveal variations in the presence of LPSO phases, MF structure, and especially grain size, leading to divergent mechanical and corrosion properties. The Bridgman approach surprisingly stands out, ensuring superior mechanical properties due to kink and texture strengthening.

Four novel magnesium alloys (Mg-4Ca-1Y, Mg-4Ca-1Y-1Al, Mg-4Ca-1Y-1Zn, and Mg-4Ca-1Y-1Al-1Zn, in wt%) specifically designed for application in the aerospace industry were processed by 12 passes of equal channel angular pressing. The resulting microstructure and mechanical properties were investigated. The thermomechanical processing led to significant grain refinement, resulting in a mean grain size from 0.6 mu m to 1.6 mu m, depending on the chemical composition. Detailed microstructural analysis revealed seven intermetallic phases, including the LPSO 18 R in the Mg-4Ca-1Y-1Zn alloy. The resulting microstructural state is significantly affected by aluminium addition, which prevents the formation of the LPSO 18 R and Mg3Zn3Y2 phases in the Mg-4Ca-1Y1Al-1Zn alloy. Mechanical performance was affected by grain boundary segregation, which plays a crucial role in grain boundary cohesion and contributes to the brittle behaviour observed in the Mg-4Ca-1y-1Zn alloy. However, aluminium addition reduces the elemental segregation, resulting in higher ductility. The ultrafine-grained microstructure, combined with a dense distribution of secondary phase particles, significantly increased strength. The Mg-4Ca-1Y-1Al-1Zn alloy exhibits the best mechanical properties with a high tensile yield strength of 291 MPa and moderate ductility of 6.5 %.

This work deals with the preparation and characterization of TiAlV/ZnAlCu composite materials. The aim is to create a model for biomaterial with good biocompatibility and acceptable mechanical properties. Infiltrating zinc into the reinforcement made of the titanium alloy could significantly improve the osseointegration of the bioimplant made from this material. The investigated reinforcements of three different geometries made from Ti-6Al-4V prepared by the SLM method (selective laser melting) were infiltrated with molten zinc or the Zn-based alloy. Two infiltration approaches were used—suction of the melt using a vacuum pump and centrifugal casting. By these procedures, different infiltration rates were achieved. Furthermore, the mechanical properties of the prepared composite materials were characterized by compression tests. The results were compared with the mechanical properties of the Ti-6Al-4V alloy reinforcement.

The application of sol-gel coatings on titanium-based materials offers a promising approach for enhancing their bioactivity, antibacterial properties, and adhesion, particularly for biomedical applications. This study focuses, for the first time, on the preparation and characterization of sol-gel TiO2-based coatings containing hydroxyapatite and silver in 3D-printed porous gyroid and dodethick structures. TiO2-based coatings on the standard wrought Ti-Al-V alloy rods were used as a reference. The coatings were applied via the specific dip-coating process developed by the author team. The microstructural analysis revealed that the sol-gel coatings on the reference wrought rod samples were homogeneous and well-adhered. The coatings on the porous gyroid and dodethick structures exhibited some localized cracking due to the complex geometry of the porous structures. Bioactivity was evaluated through the standard in vitro simulated body fluid tests, confirming hydroxyapatite precipitation on HA-containing coatings. Antibacterial properties were assessed against Escherichia coli, demonstrating nearly 100 % bacterial inhibition for Ag-containing coatings. Cytotoxicity tests with L929 fibroblast cells indicated that coatings with lower Ag concentrations in sol were non-toxic, while higher Ag concentrations in sol resulted in reduced cell viability, particularly in gyroid structures.

The present work focuses on the characterization of the ultra-high-strength 1.2709 maraging steel produced by the Direct Energy Deposition (DED) technique, either in its as-built or as-built + heat-treated state. Scanning electron microscope micrographs and X-ray diffraction patterns showed that the heat treatment (namely, solution annealing and aging) had minimal impact on the microstructure changes of the maraging steel. The material is characterized by fine cellular or dendritic microstructure containing several percent of the ductile γ-austenite phase in both as-built and as-built + heat-treated states. A small amount of the Ni3Mo0.5Ti0.5 intermetallic phase was observed even in the as-built state of the material. The heat treatment caused a substantial improvement of the mechanical properties through the homogeneous precipitation of nano-sized needle-shaped Ni3Mo0.5Ti0.5 intermetallic phase. Tensile yield strength increased from 753 to 1957 MPa, ultimate tensile strength—from 991 to 2024 MPa, and microhardness—from 350 to 700 HV0.1. The present results are also compared with those obtained for the same material produced by the more commonly used Laser Powder Bed Fusion (L-PBF) technique. Despite having a coarser microstructure with a presence of γ-phase than the LPBF-printed material, the DED-printed maraging steel exhibited greater precipitation hardening while maintaining 5

In this study, the effect of laser treatment on the surface of 3D-printed TiAl6V4 alloy with triply periodic structures was examined. As-printed and chemically etched samples served as references to assess surface changes. Microscopic analysis confirmed that laser treatment caused remelting and wave-like structures, while rapid cooling led to cracks through the new layer. Chemical and phase analyses showed the presence of TixOy (x = 1–2; y = 1–3) compounds, with variations between untreated and treated samples. Both modification methods removed un-sintered powder, but laser treatment preserved strut thickness, benefiting mechanical properties. In particular, the aim of the surface modification was to eliminate sintered particles to minimize the risk of detachment in in vivo applications, thereby enhancing implant reliability. The best mechanical performance was in untreated samples, with laser-treated ones showing only minor reduction. For example, a diamond-structured sample had a yield strength of 93 ± 2 MPa before treatment and 89 ± 3 MPa after. Additionally, surface hardness increased by about 60

Maraging steel is a high-performance material valued for its exceptional properties, making it ideal for demanding applications such as aerospace, tooling, and automotive industries, where high strength, toughness, and precision are required. These steels can be prepared by powder metallurgy techniques, which offer new processing possibilities. This paper introduces novel thermal powder pre-treatment and its impact on the final mechanical properties. Solid solution pre-treatment results in a modest improvement in strength (from 972 MPa to 1000 MPa), while the use of pre-aged powder achieves the highest strength (1316 MPa) and lowest ductility (2.6%). A self-composite material is created by mixing pre-treated powders with the same chemical composition but different properties. Such material was characterized by intermediate strength (1174 MPa) and ductility (3.1%). Although challenges such a porosity and oxidation were present, this approach allows for tuning of mechanical properties by mixing pre-treated powders, offering significant potential for advanced engineering applications.

The Ti-6Al-4V alloy is widely used as a material for medical implants. In the future, it may be employed for 3D printing using the selective laser melting method. The advantages of 3D printing are for example production of complex shapes or ability to create customized implants. One of the disadvantages of this method is the deterioration of mechanical properties, particularly the ductility of the alloy, caused by high residual stress resulting from rapid cooling during printing. This article aims to characterize the microstructure and defects of the printed alloy and the impact of hot isostatic pressing. Optical microscopy, scanning electron microscopy, and micro-computed tomography were utilized for the study. It was found that the heat treatment has a significant effect on the pore size and microstructural transformation. These findings could lead to the optimization of the manufacturing process and improve the quality of implants made from this alloy.

The Mg-Y-Zn alloy system is well known for its outstanding combination of high strength and ductility, even at relatively low concentrations of alloying elements. This exceptional performance is primarily attributed to its characteristic microstructure, which features Long-Period Stacking Ordered (LPSO) phases and the distinctive Mille-Feuille Structure (MFS). Kink-induced strengthening, developed during thermomechanical processing, has emerged as a promising strategy to simultaneously enhance strength and ductility. In this study, the beneficial effect of pre-deformation aimed at introducing additional kinks into the microstructure prior to extrusion is demonstrated. The subsequent extrusion process promotes dynamic recrystallization (DRX), generating fine DRX grains while preserving kink structures in the non-DRX regions. As a result, the yield strength is enhanced by approximately 80 MPa, accompanied by a slight improvement in ductility.