Ti6Al4V Alloy Powders Research Articles

Low-temperature creep performance of additive manufactured Ti–6Al–4V

Abstract Additive manufacturing enables the fabrication of versatile and cost-effective metallic-alloy components from a digital data model. This study explores the prospects of selective laser melting (SLM), an additive manufacturing technique, for fabricating Ti6Al4V alloy components from Ti6Al4V alloy powders. Selective laser melting parameters, such as laser power, scanning speed, powder thickness, hatching space, and scanning strategy, are carefully selected through a series of experiments. The metallurgical characteristics (microstructure, grain orientation, and phase composition), microhardness, and creep performance of the as-fabricated specimens are tested and analyzed. The kinetics of phase transformation and rupture mechanism are determined using advanced instrumental characterization tools, such as field emission scanning electron microscope, energy dispersive X-ray spectroscope, X-ray diffractometer, and transmission electron microscope.

Properties of Ti–6Al–4V Alloy Powders for Selective Electron-Beam Additive Manufacturing of Products

Properties of Ti–6Al–4V Alloy Powders for Selective Electron-Beam Additive Manufacturing of Products

Developing Four Powder Recycling Strategy for Sustainable Additive Manufacturing 3D Printing Process

This paper presents a detailed analysis of four different powder recycling strategies for the metal additive manufacturing process focused on examining the efficacy of recycling Ti6Al4V alloy powder for the Laser-Based Powder Bed Fusion (LBPF) process. The study evaluates four distinct recycling strategies (A, B, C, D) and their impact on powder-saving mechanisms. The experimental methodology involves careful leftover powder sampling, implementation of recycling strategies and print cycle analysis from each recycling strategy. The results show that Strategies C and D exhibit the lowest powder waste, allowing 6 times the reuse of leftover powder and producing 384 parts with minimal powder waste at the end of the process. Strategy B also performs well, enabling 8 cycles and building 512 parts with only a small amount of powder wasted. Conversely, Strategy A yields the highest powder waste despite achieving the same number of cycles and prints. This proposed approach requires a total volume of 224,000 mm3 of powder for each build. This entails using 500g of gas-atomized Ti-6Al-4V powder, with an average particle size D90 of approximately 50 μm. This features a continuous mixing technique, wherein each build combines 50% virgin powder with 50% of the previously collected and sieved powder.

Dynamics of the laser–powder interaction in the Ti6Al4V powder feeding process of laser-directed energy deposition additive manufacturing

Laser-directed energy deposition (L-DED) utilizes a high-power laser and coaxial powder feed to rapidly fabricate high-quality components with intricate structures. However, the complex interaction between the powder stream and laser beam is not yet fully understood. Particularly, the morphological evolution of the droplets after powder melting is closely related to the quality of component formation. In this study, the dynamical mechanism of the aggregation and evolution of molten powder after laser–powder interaction was investigated. The Ti6Al4V powder flow was observed at various laser powers using a high-speed camera. Imaging of the molten droplets at approximately 50,000 frames·s−1 was conducted, depicting the aggregation of molten powder into droplets of different sizes and shapes, mainly consisting of spherical and ribbon droplets, after laser–powder interaction. A transient numerical model was established with consideration of the mutual influence of gravity, recoil pressure, and surface tension, depicting the temporal evolution of the temperature field and droplet morphology. The simulation results indicated that the balance between the surface tension, gravity, and recoil pressure determined the morphological evolution of the molten droplets. When spherical and ribbon droplets fell into the molten pool, the maximum velocities within the pool increased by 24 % and 69 %, respectively. This phenomenon reduced the stability of the molten pool to a certain extent and affected the print quality of the part. This study deepens our comprehension of the dynamic mechanisms of Ti6Al4V alloy powder melting evolution, providing invaluable insights for optimizing L-DED processes.

In situ synthesis and regulation of spherical Ti6Al4V powder by calciothermic self-propagating metallurgy

In this paper, spherical Ti6Al4V alloy powder was successfully prepared by calciothermic self-propagating rapid reaction method, in which TiO2, V2O5, Al and Ca were used as raw materials. The reduction reaction can be completed in minutes with no need for any external energy and additives in the reaction process. By investigating the influence of the additives, the amount of reductant Ca added, the reaction pressure and the particle size of Ca, on the composition as well as the morphology of the product, the optimal alloy powder with an low oxygen content of 0.21 wt% was obtained, whose average particle size and specific surface area were 15.28 μm and 0.284 m2/g respectively. Moreover, this research implied the adiabatic temperature of the system and the liquid Ca are the main factors that pose influence to the powder morphology during sintering-reduction-spheroidization-solidification process. Compared with the traditional Ti6Al4V alloy powder preparation process, this process stands out with characteristics of high purity, short production cycle and environmental friendliness, which show high commercialization potential for industrial preparation of Ti6Al4V and similar alloy powders.

Recycled Ti6Al4V alloy powder reinforced polyurethane core based sandwich structures: Mechanical and modal properties

In this study, recycled Ti6Al4V alloy powder was utilized as a reinforcement to enhance the mechanical and modal properties of polyurethane foam (PUF) core-based sandwich composites. Sandwich composite having carbon fiber reinforced polymer (CFRP) composite face sheets and Ti6Al4V powder-reinforced PUF cores were manufactured. The PUF cores were reinforced with two different variants of Ti6Al4V powder based on particle sizes from 1 to 3 wt.%. The dispersion quality was investigated using scanning electron microscopy (SEM). A detailed experimental modal analysis was conducted to evaluate the modal properties in terms of the natural frequencies and damping ratios of the sandwich specimens. A comprehensive mechanical study was also conducted in terms of compression, buckling, flexural, and impact tests according to the relative ASTM standards. The experimental results demonstrated that the Ti6Al4V reinforced sandwich specimens exhibited superior mechanical and modal properties with enhanced PUF cores. Improvements in excess of 21%, 37%, and 24% were recorded in the compression, buckling, and flexural response of the reinforced specimens, respectively, compared to those of their neat counterparts. Similarly, remarkable improvements were also observed in the experimental modal and impact properties of the Ti6Al4V alloy powder-reinforced sandwich composites.

Craniofacial reconstruction using 3D personalized implants with enhanced surface properties: Technological and clinical aspects

In this study, the modification of personalized titanium implants was developed using the plasma electrolytic oxidation process. Plasma electrolytic oxidation process parameters were initially optimized using solid samples of the Ti6Al4V alloy. Oxidation was achieved in an electrolyte containing calcium and phosphorus compounds at 250 V. The oxide layer produced was characterized by the use of human osteoblasts and fibroblasts, with high biological activity of the modified titanium alloy in relation to these cells was demonstrated. Based on tomographic examinations, models were made and then personalized implants for three patients were printed from a Ti6Al4V alloy powder. These implants were subjected to plasma electrolytic oxidation treatment within the previously developed parameters and surgically placed in the craniofacial area. On the basis of postoperative studies, surgical interventions were successful, with modification of the surface using the plasma electrolytic oxidation method producing bioactive surfaces for both bone and soft tissue.

Fabrication of surface modified antibacterial Ti6Al4V alloy powder reinforced gelatin/chitosan composite scaffold for tissue engineering applications

The present work attempted to modify Ti6Al4V (Ti64) alloy powder to induce biocompatibility and antimicrobial properties by incorporating Ca2+ and Ag+ ions, respectively using a simple chemical treatment followed by ion exchange method. Thus functionally modified Ti64 alloy powders characterized using FE-SEM and Raman spectroscopic techniques indicate the formation of fine porous network structure along with the evolution of different phases of titania upon heat treatment in presence of Ca2+ and Ag+ ions. The incorporation of Ca2+ ions and transformation of Ag+ ions into AgNPs and their decoration on the nano porous network structure have been confirmed by the HR-TEM and EDX results. Optimized concentration of AgNPs decorated Ti64 alloy powder not only found to induce antimicrobial activity against both Gram-positive S. aureus and Gram-negative E. coli bacteria and also compatible with MG-63 cell lines. Surface functionalized Ti64 alloy powder was subsequently used as reinforcement for the fabrication of gelatin - chitosan composite scaffolds using the lyophilization technique. Thus fabricated composite scaffold was analyzed for its pore morphology and pore distribution along with its in-vitro cell toxicity towards MG-63 cell lines using MTT assay. Taken together, surface modified Ti64 alloy powder reinforced gelatin-chitosan composite scaffold with biocompatible and antimicrobial properties is expected to be suitable for tissue engineering applications.

Evaluation of mechanical properties of Ti–6Al–4V BCC lattice structure with different density gradient variations prepared by L-PBF

Based on the optimized pore size distribution and relative density, the functionally graded lattice structure is capable of achieving better mechanical properties than a uniform lattice structure with similar porosity. In this study, in order to investigate the effect of the strategy of density gradient variation on the lattice structure with similar porosity, three different density gradients were designed for the BCC-based lattice structure in parallel and perpendicular to the loading direction based on Ti–6Al–4V alloy powder and laser beam powder bed fusion technology, respectively. The results showed that the elastic modulus, yield strength and compressive strength of the lattice structure with a density varying as a logarithmic function perpendicular to the loading direction were 39.91%, 51.85% and 51.72% higher than the uniform lattice structure respectively. Moreover, the layer-by-layer collapse phenomenon was the primary aspect impacting the energy absorption in the lattice structures with density gradient parallel to the loading direction. By observing the fracture morphology of the lattice structures, it was found that all specimens exhibited dimple and smooth plane morphological features for a mixed failure mechanism of cleavage and dimple rupture, indicating that the failure mode of the lattice structures are a combination of brittle and ductile deformation. Therefore, a reasonable density gradient design can significantly improve the mechanical properties of the lattice structure with similar porosity. This work provides valuable inspiration for the design of lattice structures in engineering applications.

Raking Process for Powder Bed Fusion of Ti–6Al–4V Alloy Powder Analyzed by Discrete Element Method

In order to avoid the formation of defects in additive manufacturing (AM) by powder bed fusion (PBF) process, it is crucial to understand the relationship between the quality of powder bed and a powder spreading process. In this study, the influences of conditions of powder raking process on the densities and homogeneity of powder bed have been examined by computer simulation using Discrete Element Method (DEM) and experiment of powder bed formation using a blade-type spreader for Ti–6Al–4V powder by way of example. The results were analyzed with a special focus on the effects of the relative size of powder particles with respect to the gap between the blade and the build platform. It has been clearly shown that the gap needs to be larger than the upper bound of the distribution of powder particles diameter to obtain a high-density powder bed. The DEM simulation indicated that the blade can sweep even powder particles that are not in direct contact with the blade when the powder particles are in a close-packed tetragonal configuration. This is the probable reason for the experimental fact that powder particles smaller than half of the gap are suitable for PBF.

Compressive properties of Ti6Al4V Functionally Graded Lattice Structures via topology optimization design and selective laser melting fabrication

Owing to their comparable mechanical properties, high cell growth and nutrient transport space, lattice structures show great potential applications in replacing and repairing massive bone defects. In this work, topology optimization method was used to design cellular structures with different relative densities (RD = 0.10–0.30). Subsequently, a series of Uniform Lattice Structures (ULSs) and Functionally Graded Lattice Structures (FGLSs) with different RD gradient directions (two types: G1 type specimens with a RD gradient perpendicular to the compressing direction, while G2 type specimens with a RD gradient along the compressing direction) were fabricated via selective laser melting (SLM) technology with Ti6Al4V alloy powder. Here, ULSs as a reference were applied to investigate the mechanical properties, failure mechanism, energy absorption abilities and properties prediction of ULSs. The designed lattice structures owned comparable mechanical properties with natural bone. The mechanical properties (E = 3.13–4.73 GPa, σy = 96.90–180.05 MPa, σpl = 75.12–98.97 MPa) of G1 type specimens were sightly higher values comparing with those of ULSs, whereas mechanical properties (E = 1.42–3.75 GPa, σy = 15.93–66.21 MPa, σpl = 60.26–92.02 MPa) of G2 type specimens were a notablely lower value than those of ULSs. G2 type specimens exhibited a similar failure mechanism of layer-by-layer with ULSs, while G1 type specimens presented a mixed failure mechanism including shear-dominated and bending-dominated mode. Additionally, mechanical properties prediction methods were systematically analyzed and corresponding mathematical models were established successfully for tailoring properties of FGLSs. This work provides a comprehensive understanding that how to design and manufacture well-performance FGLSs and is significant for porous orthopedic implants applications.

Investigating the Effect of Electron Beam Melting Parameters on the Ti6Al4V Alloy: A Simulation Study

Electron beam melting is one of few techniques that can melt powder directly; is a powder bed technique, classified as an additive manufacturing method. The electron beam melting method is based on melting the material to build a high-density solid part by applying a high-energy electron beam to a powder layer in a vacuum chamber. The parameters used during the electron beam melting process significantly affect the properties of the final part being printed. These parameters are beam power, spot size, scanning speed, and layer thickness. It is necessary to choose the best values for these parameters to increase the surface integrity of the part built. This study developed a computational fluid dynamics model with a moving Gaussian distribution electron beam source applied to one layer consisting of Ti6Al4V alloy powders. The model was solved with the ANSYS software to investigate the effects of the selected parameters. The results indicated that the temperature gradients, molten pool sizes, and melting-evaporation temperature ranges were determined by applying the parameter combinations used on the beam-powder interaction throughout the process. The simulation results have emphasised the outcomes determined by the power and scanning speed parameters that directly affect the molten pool dimensions. This way, the status of powder-beam interaction zones has been identified as either within or outside the melting-evaporation range.

Silver - calcium titanate – titania decorated Ti6Al4V powders: An antimicrobial and biocompatible filler in composite scaffold for bone tissue engineering application

The present work describes a technique to develop silver nanoparticles decorated calcium titanate–titania (AgNPs-CT-TiO2) nanostructured layer over Ti6Al4V alloy powder by simple chemical and heat treatment approach. The NaOH solution and heat treatment form a uniform porous nano-network morphology of sodium titanate and subsequent calcium nitrate treatment transforms it into calcium titanate along with rutile TiO2. However, simultaneous treatment with calcium and silver nitrate solution allows the incorporation of both calcium and silver ions over the nano-network morphology leading to the formation of AgNPs decorated calcium titanate along with anatase TiO2 (AgNPs-CT-TiO2@Ti6Al4V) that collectively induces biocompatibility towards MG 63 osteoblast-like cells as well as antimicrobial activity against Staphylococcus aureus. Thus modified AgNPs-CT-TiO2@Ti6Al4V alloy powders were subsequently blended with polymethyl methacrylate to develop a composite scaffold using NaCl as a porogen. This composite could be used as a scaffold or bone cement in various bone tissue engineering applications.

Interfacial structures and strengthening mechanisms of in situ synthesized TiC reinforced Ti6Al4V composites by selective laser melting

The in-situ nanoscale TiC particles reinforced Ti6Al4V composites was prepared by selective laser melting (SLM) from the mixture of Ti6Al4V alloy powders and graphene powders, the microstructure and interface bonding of the composites were studied. The composites were mainly composed of α, α' martensite and α+β structures. More TiC were formed in the overlapping regions than that in the molten pool, the solidification rate in overlapping regions was slow, which was beneficial to TiC nucleation and growth. The TiC and Ti matrix displayed following orientation relationships: axis [0 0 1]β-Ti∥[-1 -1 1]TiC∥[0 -1 1 0 ]α-Ti, lattice plane (2 2 2)TiC //(0 0 0 2)α-Ti, lattice plane (1 1 1)TiC//(0 0 0 2)α-Ti, lattice plane (1 1 1)TiC//(1 0 -1 0)α-Ti. The TiC and Ti matrix have a small degree (6.2%) of mismatch between (1 1 1)TiC and (0 0 0 2)α-Ti, and the semi-coherent interface was occurred. TiC preferentially nucleated and grew up along its (1 1 1) plane. The situ synthesized TiC was added into the Ti6Al4V alloy, refined the grains, and increased the microhardness of the alloy. The microhardness of the composites was 13.6% higher than that of Ti6Al4V alloy. The TiC effectively pinned the dislocations and grain boundaries were responsible for the enhanced mechanical properties of the composites.

Effect of Mo Addition on the Mechanical and Wear Behavior of Plasma Rotating Electrode Process Atomized Ti6Al4V Alloy

In the current study, the effect of Mo content (1-10 wt.%) on the microstructure, hardness, bending and wear properties of Ti6Al4V-xMo alloys was investigated. The pre-alloyed and Plasma Rotating Electrode Process (PREP) atomized Ti6Al4V alloy powders and elemental Mo particles were mechanically mixed for 45 min in a zirconia jar. A uniaxial vacuum hot pressing was applied at 950°C for 30 min under 50 MPa pressure. The Ti6Al4V-xMo alloys were prepared metallographically and characterized by optical and scanning electron microscopy. The chemical composition of the different zones in the structure was determined using energy-dispersive x-ray (EDX) analysis. Mo appeared among the TiAl64V alloy particles and caused the formation of different diffusion zones. The formation of grain boundary α was effectively prevented, and instead, fine α’ and β zones were formed. Various phases formed along the particle boundaries of the Ti6Al4V alloy, and effective improvements in hardness, bending and wear resistance were obtained. However, the highest Mo content caused a decrease in mechanical properties. Ti6Al4V-5Mo alloy showed superior hardness and wear resistance.

High pressure EIGA preparation and 3D printing capability of Ti—6Al—4V powder

Abstract Ti—6Al—4V alloy powder was processed by electrode induction melting gas atomization (EIGA) at high gas pressure (5.5–7.0 MPa). The effects of atomizing gas pressure on the powder characteristics and the microstructure, along with the mechanical properties of the as-fabricated block by laser melting deposition (LMD), were investigated. The results indicate that the diameters of powders are distributed in a wide range of sizes from 1 to 400 μm, and the median powder size (d50) decreases with increasing gas pressure. The powders with a size fraction of 100–150 μm obtained at gas pressures of 6.0 and 6.5 MPa have better flowability. The oxygen content is consistent with the change trend of gas pressure within a low range of 0.06%–0.20%. Specimens fabricated by LMD are mainly composed of α+β grains with a fine lamellar Widmanstatten structures and have the ultimate tensile strength (UTS) and yield strength of approximately 1100 and 1000 MPa, respectively. Furthermore, the atomized powders have a favorable 3D printing capability, and the mechanical properties of Ti—6Al—4V alloys manufactured by LMD typically exceed those of their cast or wrought counterparts.

The new generation of the biologicalengineering materials for applications in medical and dental implant-scaffolds

Purpose: The publication aims to find the relationship between the proliferation of surface layers of living cells and the deposition of thin atomic layers deposition ALD coatings on the pores internal surfaces of porous skeletons of medical and dental implant-scaffolds manufactured with the selective laser deposition SLS additive technology using titanium and Ti6Al4V alloy. Design/methodology/approach: The extensive review of the literature presents the state-of-the-art in the field of regenerative medicine and tissue engineering. General ageing of societies, increasing the incidence of oncological diseases and some transport and sports accidents, and also the spread of tooth decay and tooth cavities in many regions of the world has taken place nowadays. Those reasons involve resection of many tissues and organs and the need to replace cavities, among others bones and teeth through implantation, more and more often hybridized with tissue engineering methods. Findings: The results of investigations of the structure and properties of skeleton microporous materials produced from titanium and Ti6Al4V alloy powders by the method of selective laser sintering have been presented. Particularly valuable are the original and previously unpublished results of structural research using high-resolution transmission electron microscope HRTEM. Particular attention has been paid to the issues of surface engineering, in particular, the application of flat TiO2 and Al2O3 coatings applied inside micropores using the atomic layers deposition ALD method and hydroxyapatite applied the dip-coating sol-gel method, including advanced HRTEM research. The most important part of the work concerns the research of nesting and proliferation of live cells of osteoblasts the hFOB 1.19 (Human ATCC - CRL - 11372) culture line on the surface of micropores with surfaces covered with the mentioned layers. Research limitations/implications: The investigations reported in the paper fully confirmed the idea of the hybrid technology of producing microporous implants and implant-scaffolds to achieve original Authors’ biological-engineering materials. The surface engineering issues, including both flat-layered nonorganic coatings and interactions of those coverings with flat layers of living cells, play a crucial role. Originality/value: Materials commonly used in implantology and the most commonly used materials processing technologies in those applications have been described. Against that background, the original Authors' concept of implant-scaffolds and the application of microporous skeleton materials for this purpose have been presented.

Short term exposure to titanium, aluminum and vanadium (Ti 6Al 4V) alloy powder drastically affects behavior and antioxidant metabolites in vital organs of male albino mice.

Titanium, Aluminum and Vanadium (Ti 6Al 4V) alloy are frequently used as surgical implant but regarding their compatibility in living systems is limited. Ti 6Al 4V was prepared from high purity constituents and Ti 6Al 4V alloy powder (25 mg/ml solvent/Kg body weight) was gavaged to albino mice for 8 days. A saline treated control group was maintained in parallel. A series of behavioral (rota rod, light and dark box, open field and novel object) test performance, complete blood count, selected serum (HDL cholesterol, LDL cholesterol, creatinine, cholesterol and triglycerides) parameters, antioxidant metabolites from vital organs (superoxide dismutase, catalase and lipid peroxidation) from vital organs and body weight were determined in both treatments. It was observed that rota rod test performance in male (P = 0.05) and novel object recognition capability in female mice (P = 0.04) were significantly reduced as compared to their respective control groups. Body weight, complete blood count and studied serum parameters remained unaffected when compared between two treatments of both genders. Concentration of superoxide dismutase in liver (P = 0.008), heart (P = 0.01) and lungs (P = 0.05) was significantly elevated while catalase concentration in liver (P = 0.001) was significantly decreased in female albino mice that were exposed to 25 mg/ml solvent/kg body weight of Ti 6 A l 4 V alloy powder. In case of male albino mice, superoxide dismutase concentration in lungs was reduced (P = 0.05) in mice exposed to Ti 6 A l 4 V alloy powder. In conclusion, our results indicated that short term exposure to 25 mg/ml solvent/Kg body weight of Ti-6Al-4V alloy powder supplementation had adversely affected selected aspects of behavior of albino mice in a gender specific manner. Analysis of antioxidant parameters in vital organs has demonstrated that the applied dose of Ti-6Al-4V alloy powder can disturb the H₂O₂ associated metabolic pathways in albino mice, especially in female mice. As this alloy is part of surgical implants, so we recommend that their effects in living systems must be extensively explored under variable dose and exposure time conditions to know more about their biocompatibility.

Mechanical Properties of Porous Structures Produced by Selective Laser Melting of a Ti6Al4V Alloy Powder

The compression Young's modulus and strength of lattice structures with porosity between 47.8% and 82.6% produced by Selective Laser Melting (SLM) of a Ti6Al4V powder were investigated. The Young's ...

Particle size characterisation of metals powders for Additive Manufacturing using a microwave sensor

The production of high-value and high-quality metal parts with complex interior structures is enabled by the use of Additive Manufacturing (AM) techniques, which use metal powders with repeatable characteristics. Of these characteristics, particle size distribution is a key factor. This paper describes a particle size sensor based on a microwave cavity. It works on the principle that the magnetic permeability of metallic powders at microwave frequencies depends strongly on the particle size distribution of the powder owing to the classical skin effect. The sensor's capability is demonstrated by measurement of the permeability of a range of Ti6Al4V alloy powders with different particle size distributions. Permeability is shown to be congruent generally with the existing theory. The reduced imaginary permeability compared with the theoretical case observed for larger particle sizes is shown to be consistent with simulation. The method is also demonstrated to be highly precise, able to detect changes of <0.1μm for particles of average radii of approximately 11.7μm. Increases in sensitivity are possible by optimising the sensor design so that it operates in the regime where the permeability changes most rapidly as a function of particle size.