Search Results (166)

The advent of additive manufacturing (AM), also known as 3D printing, has revolutionized the production of titanium alloys, offering significant advantages in fabricating complex geometries with enhanced mechanical properties. This study investigates the variant-specific deformation mechanisms in HIP-treated TA15 (Ti-6.5Al-2Zr-1Mo-1V) titanium alloy, fabricated via selective electron beam melting (SEBM). The alloy exhibits a dual-phase (α+β) microstructure, where six distinct α variants are formed through the β→α phase transformation following the Burgers orientation relationship. Variant selection during AM leads to a non-uniform distribution of these α variants, with α6 (22.3%) dominating due to preferential growth. Analysis of the prismatic slip Schmid factor reveals that α4–α6 variants, with higher Schmid factors (>0.45), primarily undergo prismatic slip, while α1–α3 variants, with lower Schmid factors (<0.3), rely on basal or pyramidal slip and twinning for plastic deformation. In-grain misorientation axis (IGMA) analysis further reveals strain-dependent slip transitions: pyramidal slip is activated in α1–α3 variants at lower strains, while prismatic slip becomes the dominant deformation mechanism in α4–α6 variants at higher strains. Additionally, deformation twins, primarily {10–12}<1–101> extension twins (7.1%), contribute to the plasticity of hard-oriented α variants. These findings significantly enhance the understanding of the orientation-dependent deformation mechanisms in HIPed TA15 alloy and provide a crucial basis for optimizing the performance of additively-manufactured titanium alloys. Full article

Alloys of Ti-10Ta-1.6Zr (wt%) with and without 3 wt% Cu made by arc-melting, heat-treated in two stages and quenched to have α + β microstructures were studied. These alloys were studied for potential replacement of Ti-6Al-4V alloys because Ta and Zr are more biocompatible than Al and V, and copper was added for potential antimicrobial properties. The heat-treated samples were investigated by SEM-EDX, transmission Kikuchi diffraction (TKD) and XRD. When studied at a higher magnification, the heat-treated alloys revealed a bi-lamellar microstructure, consisting of broad α lamellae and β transformed to fine α′ lamellae with various orientations. The fraction β transformed to fine α′ lamellae was higher in the alloy with Cu than that without Cu. Furthermore, copper was found to lower the solubility of tantalum in the β. The hardest alloy was the heat-treated alloy containing Cu, albeit with a wide standard deviation, probably due to the high fraction of martensitically transformed β. Full article

Based on their high mechanical strength, Ti-based high-entropy alloys (HEAs) are of great potential as materials for high-performance reduced-diameter dental implants. Despite previous studies demonstrating their corrosion resistance in various simulated body fluids, their resistance in simulated buccal conditions has yet to be confirmed. In this work, the corrosion behavior of two Ti-based HEAs, TiZrHfNb, and TiZrHfNbTa was evaluated in comparison to CP-Ti and Ti-6Al-4V in artificial saliva (AS) solution and in AS with fluoride ion content (ASF). A set of electrochemical tests (electrochemical impedance spectroscopy, cyclic polarization, and Mott–Schottky) was employed and complemented with surface characterization analyses (scanning electron microscopy and atomic force microscopy) to determine dissolution and passivation mechanisms of the alloys. In general, the HEAs exhibited a far superior corrosion resistance compared to CP-Ti and Ti-6Al-4V alloys in both solutions. In the AS solution, the TiZrHfNb exhibited the highest polarization resistance and pitting potential, indicating a high corrosion resistance due to the formation of a robust passive layer. Whilst in the ASF solution, the TiZrHfNbTa showed a greater corrosion resistance due to the synergistic effect of Nb and Ta oxides that enhanced passive film stability. This finding emphasizes the role of Ta in elevating the corrosion resistance of Ti-based HEAs in the presence of fluoride ions and confirms the importance of chemical composition optimization in the development of next-generation dental alloys. Based on its electrochemical corrosion behavior, TiZrHfNbTa HEAs are promising new materials for high-performance reduced-diameter dental implants. Full article

This study investigates the effect of duo-ceramic zirconia and silicon nitride (ZrO₂-Si₃N₄) particles and their reinforcement proficiencies on a Ti6Al4V alloy, consolidated using the spark plasma sintering (SPS) technique. The selected sintering parameters are, viz., 900 °C temperature, 50 MPa pressure, 10 min of holding time, and 100 °C/min of sintering rate. SEM/EDS and XRD equipment were used to disclose the microstructural evolution and phase identification of created composites. The mechanical characteristics of the resulting composites were determined using the nanoindentation technique. All consolidated sintered composites showed excellent densification, with sample relative densities reaching 96.65%. Significant improvements were also made in their nanomechanical characteristics; among the composite samples with different volume fractions, the ceramics with the lowest volume percentage had the best mechanical characteristics, whereas the sintered samples with the highest ceramic volume percentage showed a decrease in mechanical proficiencies and relative density. Composite S1, with the lowest volume fraction of the duo-ceramic particles, was seen to have a significant mechanical property improvement better than other composites, S2 and S3, in terms of measured Vickers microhardness, elastic modulus, and nano hardness values at a sintering temperature of 900 °C. Consequentially, composite specimens S2 and S3’s mechanical characteristics and relative densities dropped as the volume fractions of the duo-ceramic particles increased. Full article

One of the most popular alloys for biomedical applications is TiAl6V4. Even though TiAl6V4 is widely used, it faces several challenges. Firstly, TiAl6V4 is prone to stress shielding caused by the difference in Young’s moduli of the alloy (110 GPa) and human bones (20–30 GPa). Secondly, there is the presence of cytotoxic elements, aluminum and vanadium. Researchers have proposed Ti-35Nb-7Zr-5Ta (TNZT) alloy to overcome these disadvantages, an excellent substitute for natural human bones. This alloy offers a lower elastic modulus (up to 81 GPa), much closer to human bones than TiAl6V4 alloy. Also, TNZT alloy contains no cytotoxic elements and has excellent biocompatibility and high corrosion resistance. Given the positive outcomes on powder-mixed micro electro-discharge machining (PM-μ-EDM) of Ti alloy using hydroxyapatite (HA) powder, we studied the machinability of TNZT alloy using HA powder mixed-μ-EDM by changing the HA powder concentration (0, 5, and 10 g/L), gap voltage (90, 100, and 110 V), and capacitance (10, 100, and 400 nF) according to the Taguchi L9 method. Machining performance metrics such as material removal rate (MRR), overcut, and circularity were examined using a tungsten carbide tool of 237 µm diameter. The results showed an overcut of 10.33 µm, circularity of 8.47 µm, and MRR of 6030.89 µm³/s for the lowest energy setup. Full article

As a promising candidate for next-generation aviation structural materials, lightweight refractory high entropy alloys (HEAs) exhibit high strength, low density, and excellent high-temperature performance. In this study, we investigated the influence of local chemical ordering on the properties of Ti–V–Zr–Nb–Al HEAs using Monte Carlo (MC) simulations based on density functional theory (DFT) calculations. We established that the chemical short-range ordering (SRO) in Ti–V–Zr–Nb–Al HEAs increases with the Al content, resulting in a gradual increase in stacking fault energy (SFE). This theoretical investigation suggests that SRO can be utilized to tailor the performance of HEAs, thereby providing guidance for the scientific design of macroscopic mechanical properties. Full article

The 6061 aluminum alloy is a commonly used metal material for sports equipment but is vulnerable to the external environment and corrosion. A novel V-Zr-Ti composite conversion coating was successfully prepared on the surface of 6061 aluminum alloy, and a thorough investigation was conducted into the effect of the conversion parameters. Furthermore, the microstructure of the conversion coating, element contents of the coating surface, and dynamic evolution characteristics of the conversion solution were systematically investigated, and furthermore, the relationship among them was established. The results show that the optimal conversion time (CTI) and conversion temperature (CTE) for the VZrCC are 12 min and 45 °C. The VZrTiCC can gradually fill surface scratches during the coating-forming process, resulting in a relatively flat and even surface morphology. The conversion element contents on the VZrTiCC surface demonstrated a gradual increase, and the deposition rate was characterized by high Ti, medium Zr, and low V. The phase of the coating is predominantly constituted by metal oxides derived from conversion compositions, with a minor proportion of fluoride. Furthermore, the VZrTiCC can significantly enhance the corrosion resistance of an Al alloy matrix due to its low i_corr and average corrosion rate (ACR), and its corrosion resistance is about 5 times higher than that of the Al alloy matrix. Eventually, the formation process of the VZrTiCC with three key stages was proposed. In subsequent studies, to further establish a composition design framework for the conversion coating, a silane aqueous solution will be added to the existing V-Zr-Ti conversion solution, and a systematic study will be conducted on the V–organic composite conversion coating using computational molecular dynamics simulation combined with experimental characterization. Full article

This review paper provides a comprehensive synthesis of the current advancements in investigations of different titanium-based alloys, including pure titanium, commercially available Ti6Al4V, and modified alloys, such as Ti-Nb-Zr-Fe alloys, for biomedical applications. Several researchers have explored the effects of alloying elements and processing techniques on enhancing the mechanical, chemical, and biological properties of these materials. Ti-Nb-Zr-Fe alloys are of particular interest due to their potential to address critical requirements in medical applications, including reduced Young’s modulus, superior corrosion resistance, biocompatibility, and mechanical strength. Despite substantial progress, the detailed mechanisms for optimizing these properties remain underexplored in the current literature. The main objective of the present review paper is to emphasize the importance of ongoing investigations aimed at overcoming challenges such as biocompatibility concerns, fatigue resistance, and wear under biological conditions. By critically analyzing existing data, this study highlights gaps in knowledge and identifies opportunities for advancing research on these alloys. Specifically, this review paper highlights the need for targeted studies to reduce the Young’s modulus and improve other critical characteristics of Ti-Nb-Zr-Fe alloys to better meet the demands of orthopedic implants, dental prosthetics, and cardiovascular devices. Even if the current scientific literature is ample on this topic, we consider that through this review we can positively contribute to the collective effort in this field trying to fill some gaps, including some updates on the topic, time frames, advantages, and limitations, and pave the way for further advancements that could revolutionize biomedical implant technology. The review encompasses studies performed over the last 5 decades, specifically from 1975 to 2025, to ensure the inclusion of the most relevant and up-to-date research. This approach aims to highlight the significant progress made while situating the findings within the broader context of ongoing investigations. Full article

With superior manufacturing freedom capability, Selective Laser Melting (SLM) technology is capable of fabricating high-strength Ti-6Al-2Zr-1Mo-1V (TA15) complex titanium alloy parts, thereby finding extensive applications in the aerospace sector. This paper primarily investigates the influence of process parameters on the relative density, microstructure, and mechanical properties of SLMed TA15 under conditions of similar laser linear energy density. The results indicate that the laser linear energy density significantly affects the single-track morphology of SLMed TA15; excessive energy density leads to keyhole defects, while insufficient energy density causes balling phenomena, resulting in discontinuous clad tracks. When the laser linear energy density is appropriate, the scanning spacing affects the forming density of the parts, with both excessively large and small spacings having adverse effects. With a fixed scanning spacing of 100 μm, high-density samples can be produced within a suitable range of linear energy density. However, when the laser linear energy density is comparable, a lower scanning speed leads to heat accumulation, causing in situ decomposition of the α’ martensite and the formation of coarser α + β phases, which reduces strength and hardness but improves plasticity. At a laser power of 90 W, a scanning speed of 400 mm/s, and a scanning spacing of 100 μm, the specimen exhibits a tensile strength of 1233 MPa and an elongation of 8.4%, achieving relatively excellent comprehensive properties. Full article

Metal additive manufacturing processes induce residual stress in as-built components. These residual stresses are detrimental to part quality as they can induce defects such as warping and delamination. In some cases, when complex components are built, residual stress can even cause a build job to fail due to the recoater crashing into the distorted part. In this paper, the residual stress values of Ti6Al4V and Ti-6Al-2Sn-4Zr-6Mo alloys were evaluated by the cantilever approach and by the X-ray diffraction sin²(Ψ) method. The results showed that, as expected, Ti6Al4V as-built cantilevers displayed high distortion and von Mises equivalent stress values up to 494 MPa. On the contrary, as-built Ti-6Al-2Sn-4Zr-6Mo cantilevers were characterized by almost null warping and a residual stress value in the as-built state of 191 MPa. This different behavior is mainly due to the different properties of the hexagonal α’ martensite in Ti6Al4V and the soft orthorhombic α’’ martensite in Ti6246. The post-processing heat treatment significantly reduced the residual stress in Ti6Al4V, lowering it to 44 MPa, while, in the case of Ti-6Al-2Sn-4Zr-6Mo, the post-processing heat treatment did not affect the residual stress conditions. These findings suggest that Ti-6Al-2Sn-4Zr-6Mo could be a suitable candidate for the additive manufacturing production of extremely complex parts, as it could reduce the risks associated with recoater crashes and job failures. Full article

The resistance to near-threshold fatigue crack growth and its correlation with the microstructure of the Ti-5Al-3Mo-3V-2Zr-2Cr-1Nb-1Fe alloy were investigated. K-decreasing fatigue crack propagation rate tests were conducted on compact tension samples (ASTM standard) with a stress ratio R of 0.1 and a frequency of 15 HZ in a laboratory atmosphere. At a similar strength level of 1200 MPa, the sample with a fine basket-weave microstructure (F-BW) displayed the slowest near-threshold fatigue crack propagation rate compared with the samples with equiaxed (EM) and basket-weave (BW) microstructures. The fatigue threshold value (ΔK_th) was 4.4 MPa·m^1/2 for F-BW, 3.6 for BW, and 3.2 for EM. The fracture surfaces and crack profiles were observed by scanning electron microscopy (SEM) and electron backscatter diffraction (EBSD) to elucidate the mechanism of fatigue crack propagation in the near-threshold regime. The results revealed that the near-threshold crack growth in the three samples was primarily transgranular. The crack always propagated parallel to the crystal plane, with a high Schmid factor. In addition, the near-threshold fatigue crack growth behavior was synergistically affected by the crack tip plastic zone and crack bifurcation. The increased fatigue crack propagation resistance in F-BW was attributed to the better stress/strain compatibility and greater number of interface obstacles in the crack tip plastic zone. Full article

In this work, the high cycle fatigue behavior and tensile properties of Ti-Al-Mo-Cr-V-Nb-Zr-Sn titanium alloy at room temperature with a basketweave structure and bimodal structure were studied. The results show that the fatigue strength of the basketweave structure is higher, while the balance of strength and plasticity of the bimodal microstructure is better. However, the fatigue performance of the bimodal microstructure is unstable due to the bilinear phenomenon of the S-N curve. By fractographic analysis and the study of the crystal orientation, as well as the slip traces of the primary α grains and β matrix at the facets, it was found that the facets are formed on the {$10\overline{1}1$}<$11\overline{2}0$> slip system with the highest Schmid factor, and the microcracks grow along the {$110$}<$111$> slip system in the β grain, but the driving force of microcrack propagation may exceed the restriction of crystallographic orientation. Based on the conclusions above, the phenomenological models of the fatigue crack initiation mechanism of Ti-Al-Mo-Cr-V-Nb-Zr-Sn titanium alloy are established. Full article

This article compares the properties of the diamond-like carbon (DLC) coating with those of ZrN and (Zr,Hf)N coatings deposited on the Ti-6Al-4V titanium alloy substrate. To improve substrate adhesion during the deposition of the DLC coating, preliminary etching with chromium ions was conducted, ensuring the formation of a chromium-saturated diffusion surface layer in the substrate. A Si-DLC layer followed by a pure DLC layer was then deposited. The hardness of the coatings, their surface morphology, fracture strength in the scratch test, and tribological properties and wear resistance in the pin-on-disk test in contact with Al₂O₃ and steel indenters were investigated. The structure of the DLC coating was studied using transmission electron microscopy, and its corrosion resistance in an environment simulating blood plasma was also investigated. In the pin-on-disk test in contact with Al₂O₃ and AISI 52100 indenters, the DLC-coated sample demonstrates a much lower friction coefficient and significantly better wear resistance compared to the nitride-coated and uncoated samples. Both nitride coatings—(Zr,Hf)N and ZrN—and the DLC coating slow down the corrosive dissolution of the base compared to the uncoated sample. The corrosion currents of the (Zr,Hf)N-coated samples are 37.01 nA/cm², 20% higher than those of the ZrN-coated samples. The application of (Zr,Hf)N, ZrN, and DLC coatings on the Ti-6Al-4V alloy significantly inhibits dissolution currents (by 30–40%) and increases polarization resistance 1.5–2.0-fold compared to the uncoated alloy in 0.9% NaCl at 40 °C. Thus, the DLC coating of the described structure simultaneously provides effective wear and corrosion resistance in an environment simulating blood plasma. This coating can be considered in the manufacture of medical products (in particular, implants) from titanium alloys, including those functioning in the human body and subject to mechanical wear (e.g., knee joint endoprostheses). Full article

Ti-6.5Al-2Zr-1Mo-1V/TiB metal matrix composites with 3 wt.% of TiB₂ were obtained using vacuum arc melting and spark plasma sintering methods and compared with an unreinforced Ti-6.5Al-2Zr-1Mo-1V alloy. The microstructures of the unreinforced Ti6.5Al-2Zr-1Mo-1V alloy in the as-cast and as-sintered conditions were quite typical and consisted of colonies of α-lamellae embedded in the β matrix. The microstructure of the as-cast Ti-6.5Al-2Zr-1Mo-1V/TiB composite composed of TiB fibers randomly distributed within the two-phase α/β matrix, while the as-sintered composite had a network-like microstructure, in which areas of the two-phase α/β matrix were delineated by walls of TiB fibers. At room temperature, the yield strength of the as-cast and as-sintered Ti-6.5Al-2Zr-1Mo-1V alloy were 800 and 915 MPa, respectively, with a plasticity of 18% in both conditions. The addition of TiB fibers contributed to a ~40 and 50% strength increment, with values of 1100 and 1370 MPa for the as-cast and as-sintered composites, respectively. In the as-sintered composite, the strengthening effect reduced at 400 °C and almost disappeared at elevated temperatures of 800–950 °C. The as-cast composite showed much higher strength during warm and hot deformation—at 800–950 °C, the yield strength of the as-cast composite was 50% higher compared to the Ti-6.5Al-2Zr-1Mo-1V unreinforced alloy. A higher rate and degree of globularization were established for the as-cast composite compared to the unreinforced alloy. For the as-sintered composite, a noticeably lower rate and degree of globularization was shown. During hot compression of the as-cast composite, TiB fibers reoriented towards the metal flow direction, while the network microstructure formed in the as-sintered composite transformed into clusters of borides unevenly distributed within the matrix. Based on the obtained results, the apparent activation energy of plastic deformation was calculated, and the operating deformation mechanisms were discussed both for the as-cast and as-sintered composites. The Arrhenius flow stress model and the dynamic material model were used to evaluate the deformation behavior of composites beyond the experimentally studied temperatures and strain rates. Full article

Our study examined how different titanium alloy Ti6Al4V (Ti64) and zirconia (ZrO₂) surfaces, ranging from rough to very smooth, affect the expression of elastase (NE), matrix metalloproteinase (MMP)-8, MMP-9, and extracellular traps (NETs) by neutrophils. Discs of Ti64 and ZrO₂, 10 mm in diameter and 1.5 mm thick, were created using diamond-impregnated polishing burs and paste to produce rough (Ra > 3 µm), smooth (Ra ≥ 1 to 1.5 µm), and very smooth (Ra < 0.1 µm) surfaces. Neutrophils from Wistar rats were cultured on these surfaces, and the culture supernatants were then examined for NE, MMP-8, and MMP-9 using ELISA. At the same time, NET formation was demonstrated immunohistochemically by staining neutrophils with CD16b and DNA with DAPI. Overall, the expressions of NE and MMP-8 were significantly higher from neutrophil culture on Ti64 and ZrO₂ rough surfaces compared to the very smooth surface (R > S > VS) after 2 h and 4 h of culture. The expression of MMP-9 also increased with culture time; however, no significant surface effects on expression were observed. Similarly, rough Ti64 and ZrO₂ surfaces (R & S) also showed significantly larger NET formation compared to the very smooth surface (VS) after 4 h and 8 h cultures. Our findings suggest that increasing surface roughness on Ti64 and ZrO₂ triggers higher NE, MMP-8, and NET formation secretion. Full article