Ti6Al4V Powder Research Articles

Preparation of Ti6Al4V Slurry for Digital Light Processing 3D Printing

Ti6Al4V powders have higher light absorption and density, which pose significant challenges for metal light curing. It is necessary to investigate the performance of Ti6Al4V slurries to achieve high‐quality green bodies. To optimize Ti6Al4V slurry for light‐curing printing, the influence of slurry components on the rheological and curing properties of slurry is studied. The viscosity values of slurries are measured under different solid loading, and it is found that the viscosity values of the slurry are proportional to the solids loading. It is found that the curing performance of the slurry with photoinitiators 819 is superior to that of the slurry with diphenyl (2,4,6‐trimethylbenzoyl) phosphine oxide as the photoinitiator 819. The effect of the concentration of dispersant KOS110 on the viscosity of slurry is measured, and the results show that the viscosity of the slurry is increased due to the bridging flocculation of the dispersant KOS110 in the slurry. It is found that green bodies can be printed successfully when the solid loading of Ti6Al4V slurry is 40 vol%, the concentrations of photoinitiator 819 and dispersant KOS110 are 1 and 3 wt%, respectively. The printing parameters are energy density of 336 mJ cm−2 and a model thickness of 20 μm.

Biological response guided by hybrid additive manufacturing for Ti6Al4V titanium alloy

This research evaluates the cellular response from Ti6Al4V scaffolds fabricated by hybrid additive manufacturing (AM) with the goal of improving bone tissue growth and biocompatibility of titanium implants. Since cellular adhesion and viability are subject to microstructure, hybrid AM was sought to dictate biological response by creating a dispersed and gradient microstructure within implants. The objective was to evaluate the effect of gradient microstructures within Ti6Al4V scaffolds on cellular metabolic activity. Gradient microstructure was incorporated within scaffolds by hybrid AM coupling directed energy deposition (DED) with interlayer milling. The cellular response from the scaffolds was evaluated using cell viability assays in two stages: the Ti6Al4V powder used for DED was first evaluated, followed by the fabricated scaffolds. Cell viability on hybrid AM scaffolds was compared with as–printed, i.e., DED-fabricated and annealed Ti6Al4V scaffolds. The cell viability assays demonstrated that Ti6Al4V powder was non-toxic as cells cultured with powder exhibited metabolic activity similar to cells in growth media without powder. The cell viability study on scaffolds indicated, on average, cell adhesion on hybrid AM scaffolds outperformed as–printed and annealed scaffolds. This study provides preliminary data demonstrating the use of hybrid AM to dictate cell activity. A larger sample set would be required in future work to understand the effects of grain refinement through coldworking on biological response.

Comparative study on surface wettability, bio-tribology, and cytotoxicity of selective laser melted 316L SS, CoCrMo, and Ti6Al4V metallic biomaterials

The present work deals with fabricating metallic implant surfaces through laser powder bed fusion-based selective laser melting (SLM) technique using the 316L SS, CoCrMo, and Ti6Al4V powders. The topographical, metallographic, and micro-hardness measurements were performed to study the fabricated parts’ surface roughness, chemical purity, and mechanical behavior. The results showed that prepared selective laser melted (SLMed) samples have nano-level roughness, high chemical purity, and improved hardness value. Further, the surface functionality was examined through surface wettability and cytotoxicity analysis, and it was found that the Ti6Al4V sample exhibits an improved hydrophilicity with a minimum contact angle (CA) value of 26.25° as compared to the 316L SS (CA: 40.23°) and CoCrMo (CA: 44.54°) samples. The cytotoxicity results for 100 % dilution indicate that the CoCrMo sample has the highest cell viability (CV: 170.03 ± 13.91), followed by 316L SS (CV: 139.47 ± 2.2) and Ti6Al4V (CV: 101.53 ± 15.44) specimens. Furthermore, the in-vitro bio-tribology analysis indicated that SLMed samples have improved friction and wear performance, with the lowest COF value of 0.12 for Ti6Al4V at 10N load as compared to the 316L SS and CoCrMo parts. However, the Ti6Al4V surface presented a high volumetric wear loss compared to 316L SS and CoCrMo counterparts at different loads, indicating a brittle behavior. The obtained outcomes dictate that the SLM technique is a promising approach to fabricating implant surfaces using Ti6Al4V metallic biomaterial with improved bulk and surface functionality.

Microstructural characterization on reused Ti6Al4V powder in direct metal laser sintering additive manufacturing

One of the biggest advantages in metal additive manufacturing using laser powder bed fusion is low powder usage compared to traditional manufacturing methods. The process can be made more efficient by enabling metal powder to be reused. Recycling promotes environmental sustainability by minimizing material wastage and decreasing the demand for raw materials, making the metal additive manufacturing process more resource efficient.In this study, Ti6Al4V powder was recycled and reused up to 50 times. In order to understand the effects of reusing powder, the study included a detailed examination of both the powder and the processing method. The microstructure and characteristics of the recycled powder were examined in extensive detail.

On morphology and roughness of upskin surfaces in laser powder-bed fusion additive manufacturing – Contouring strategy effects

The surface quality of inclined parts made by Laser powder-bed fusion (L-PBF) additive manufacturing is inferior to those made by conventional formative and subtractive manufacturing techniques. The inherited step edges formed during such layer-by-layer fabrications and partially melted or non-melted particles attached to the newly formed surface are the major causes of poor surface finish of L-PBF parts. This study is a part of a research framework, in which the effects of different contouring strategies and scan parameters on the surface morphology of inclined parts are investigated by both experimental and numerical methods. In particular, the effect of two different contour scan strategies, namely pre-contouring and post-contouring, on the upskin surface roughness of 30⁰ inclined parts is analyzed. The inclined specimens were fabricated with Ti6Al4V powder using an EOS M270 system and the upskin surfaces were measured by a white light interferometer. In addition, a multi-track multi-layer numerical approach using coupled discrete element method and thermo-fluid simulation was also performed to understand the inclined surface formation in L-PBF.The findings show that the pre-contouring strategy with high linear energy density (LED) (0.4 J/mm) results in average surface roughness (Sa) as low as 7.43 µm, whereas the lowest LED (0.05 J/mm) resulted in the highest Sa of 33.74 µm. Larger melt pool dimensions were obtained in the high LED pre-contouring simulations, which indicates a better material fusion resulting in a good surface finish. The numerical simulation showed that the upskin surface roughness is also affected by the raster scan, if the raster scanning LED is higher than that of pre-contour scans. For the post-contouring strategy studied, higher and lower LEDs were used in inner and outer contour scanning, respectively. It is indicated that the inner contour scanning with a high LED reduces the surface roughness because of a larger melt pool size, irrespective of outer contour scanning. The lowest Sa obtained was 8.24 µm for the highest LED inner contour (0.05 J/mm) case and the highest Sa was 19.95 µm, for the parts made with the lowest LED inner contour scan (0.075 J/mm) strategy. The coupled discrete-element and thermo-fluid-based simulations offer insights into the sloped surface formation and the results supported the experimental findings in qualitative manner.

Study on fabrication of multi-phase reinforcement coatings on Ti6Al4V by laser cladding for enhanced tribological performance

In order to improve the wear resistance, the multi-phase reinforcements coating with high hardness were fabricated on the surface of Ti6Al4V by laser cladding. In this study, Cr3C2 and Ti6Al4V powders, along with continuous fiber laser cladding in a protective gas of N2 atmosphere, were used to prepare a stepwise-solidifying-point multiphase composite coating (TiC, TiN, and CrN) on the surface of Ti6Al4V. The results showed that the crack-free coating with a coating depth of 1.24 mm and a maximum hardness of 1155.52 HV can be prepared on laser power of 900 W. As the laser power increases from 900 W to 1400 W, the combined effect of the soft α-Ti phase and the in-situ synthesized hard TiN phase on hardness results in a decrease in the maximum surface hardness at 1400 `W. And the surface hardness of Ti6Al4V after laser cladding increased by 2.80–2.68 times, and the wear rate decreased by 0.74–0.86 times. Due to the soft phase α-Ti and in-situ synthesized TiC-TiN secondary dendrites serve as the hard phase, which also serve as the supporting skeleton of the oxide film, and the coatings is enriched with TiO2 oxide film. Additionally, the wear mechanisms of Ti6Al4V include abrasive wear, adhesive wear, and oxidation wear. In contrast, the coatings primarily exhibit abrasive wear and oxidation wear.

Designs and mechanical responses of 3D-printed Ti6Al4V porous structures based on triply periodic minimal surfaces with different iso-values

With the increasing applications of additive manufacturing in orthopaedic implants and numerous designs of porous structures available, there is a strong need and opportunity to optimize the structure designs for improved bone integration. Here we created a unique group of sheet structures based on triply periodic minimal surface (TPMS) by varying the iso-value and systematically examined how iso-value influences the mechanical performance of sheet diamond TPMS structures compared to the Octet truss structure. Four iso-values (C) 0, 0.25, 0.5, and 0.75 were designed for sheet Diamond (OSD) TPMS with varying porosity, and Ti6Al4V powder bed fusion was used to produce the porous structures. Compressive tests revealed that iso-value C significantly affected mechanical performance, and interestingly, the impact was porosity-dependent. At high relative density (>0.25), OSD0 (C = 0) displayed the highest elastic modulus and yield strength, whereas at low relative density (<0.25), OSD0.5 showed the highest among all OSD structures. Regarding failure mechanisms, OSD0, OSD0.25, and OSD0.75 showed a mixed domination of stretching and bending, while OSD0.5 was predominantly stretching-dominated. Finite Element Analysis (FEA) found that local yielding initiated at cell nodes upon loading, followed by surface bending and the formation of single or multiple shear bands near the cell nodes. This work demonstrated the feasibility of improving the mechanical performance of porous TPMS structures by simple adjustments in their governing trigonometric functions, serving as a starting point to customize porous structures for specific applications.

Wire-arc additive manufacturing of TiB/Ti6Al4V composites using Ti-TiB2 cored wire: processing, microstructure and mechanical properties

ABSTRACT A novel wire-arc additive manufacturing (WAAM) process utilising titanium flux-cored wire (FCW) containing TiB2, Al60V40 and Ti6Al4V powders was proposed for fabricating TiB/Ti6Al4V composites. The FCW exhibited the capability in customising the composition of TiB/Ti6Al4V composites from hypoeutectic to hypereutectic by tailoring the proportion of TiB2 in blended powders. The comprehensive influence of TiB2 content on molten pool flow, compositional homogeneity and porosity of as-printed composites was attributed to the reduction of melt flowability, driven by viscosity escalation. It was unravelled the porosity was the intrinsic deficiency for the FCW-WAAM process, originating from the gases within FCW, while the interlayered TiB clusters were caused by the lagging melt of TiB2 powders. Due to directional solidification, TiB whiskers possessed a large aspect ratio and were partial to upward growth in hypoeutectic composites, which enhanced the load transfer strengthening. However, the porosity degraded the ductility of composites and caused the variation in mechanical performance.

Tailoring Laser Powder Bed Fusion Process Parameters for Standard and Off-Size Ti6Al4V Metal Powders: A Machine Learning Approach Enhanced by Photodiode-Based Melt Pool Monitoring

An integral part of laser powder bed fusion (LPBF) quality control is identifying optimal process parameters tailored to each application, often achieved through time-consuming and costly experiments. Melt pool dynamics further complicate LPBF quality control due to their influence on product quality. Using machine learning and melt pool monitoring data collected with photodiode sensors, the goal of this research was to efficiently customize LPBF process parameters. A novel aspect of this study is the application of standard and off-size powder feedstocks. Ti6Al4V (Ti64) powder was used in three size ranges of 15–53 µm, 15–106 µm, and 45–106 µm to print the samples. This facilitated the development of a process parameters tailoring system capable of handling variations in powder size ranges. Ultimately, per each part, the associated set of light intensity statistical signatures along with the powder size range and the parts’ density, surface roughness, and hardness were used as inputs for three regressors of Feed-Forward Neural Network (FFN), Random Forest (RF), and Extreme Gradient Boosting (XGBoost). The laser power, laser velocity, hatch distance, and energy density of the parts were predicted by the regressors. According to the results obtained on unseen samples, RF demonstrated the best performance in the prediction of process parameters.

Biomimetic Porous Ti6Al4V Implants: A Novel Interbody Fusion Cage via Gel-Casting Technique to Promote Spine Fusion.

An interbody fusion cage (Cage) is crucial in spinal decompression and fusion procedures for restoring normal vertebral curvature and rebuilding spinal stability. Currently, these Cages suffer from issues related to mismatched elastic modulus and insufficient bone integration capability. Therefore, a gel-casting technique is utilized to fabricate a biomimetic porous titanium alloy material from Ti6Al4V powder. The biomimetic porous Ti6Al4V is compared with polyetheretherketone (PEEK) and 3D-printed Ti6Al4V materials and their respective Cages. Systematic validation is performed through mechanical testing, in vitro cell, in vivo rabbit bone defect implantation, and ovine anterior cervical discectomy and fusion experiments to evaluate the mechanical and biological performance of the materials. Although all three materials demonstrate good biocompatibility and osseointegration properties, the biomimetic porous Ti6Al4V, with its excellent mechanical properties and a structure closely resembling bone trabecular tissue, exhibited superior bone ingrowth and osseointegration performance. Compared to the PEEK and 3D-printed Ti6Al4V Cages, the biomimetic porous Ti6Al4V Cage outperforms in terms of intervertebral fusion performance, achieving excellent intervertebral fusion without the need for bone grafting, thereby enhancing cervical vertebra stability. This biomimetic porous Ti6Al4V Cage offers cost-effectiveness, presenting significant potential for clinical applications in spinal surgery.

Prospective life cycle assessment of titanium powder atomization

The environmental sustainability of titanium powders production mainly depends by atomization that is the most diffused technology in this field, ensuring the environmental advantages of high mass flow rate, energetical efficiency and reduced waste which have greatly encouraged its diffusion on an industrial scale. However, few quantitative assessment studies have been proposed on atomization sustainability and none of them consider the many technological evolutions of atomization that the industries are working on. This study proposes a prospective life cycle assessment (LCA), of the ex-ante type, of future new Electrode Induction Gas Atomization (EIGA) and Plasma Rotating Electrode Process (PREP) that will produce Ti6Al4V powders in 2035. This time point, referring to a medium-term view is considered to ensure the relevance and the reliability of technology forecasts based on quantitative estimates. Both the systems have been modelled through data retrieved from patents to assess their future impacts. The prospective LCA shows that in the future EIGA the average impact, in each indicator, will be 50% lower for electrical consumption and 98% lower for argon consumption compared to future PREP. The future EIGA and future PREP are more sustainable than the mature EIGA (of the crucible and crucible-free type) and mature PREP (of the traditional and supreme-speed plasma type) currently on the market. The average impact reductions, respectively passing from future to mature EIGA and PREP, are 65% and 23% for electricity consumption and 11% and 28% for argon consumption. The variabilities in technological solutions, scalability and future scenarios about electricity and argon production scale all the impacts without reverse the ranking. At a structural level, the most sustainable solutions are the optimization of the geometries of the titanium bar in the future EIGA and the optimization of the disposition of the plasma gun in the future PREP. This study shows which technological advancement increase the sustainability of EIGA and PREP atomization process in the future and to what extent in the two cases.

Preparation and mechanical performance analysis of porous Ti6Al4V scaffold fabricated by direct ink writing

In order to mitigate the stress-shielding effect resulting from the stiffness disparity between titanium alloy and bone, the use of additive manufacturing to create porous Ti6Al4V components shows promise for orthopedic implant applications. In this study, a novel hot-melt–quick-frozen polyvinyl alcohol hydrogel was developed for direct ink writing to create porous titanium structures using Ti6Al4V powders with an irregular morphology. The rheological and sintering properties of inks with varying solid phase contents were examined to assess their molding quality. Furthermore, the effect of porosity on the morphology, shrinkage, and mechanical properties of the scaffolds was thoroughly investigated. The results of the experiments show that inks loaded with 65 vol. % Ti6Al4V particles exhibit the highest printing performance. Furthermore, the analysis revealed a positive correlation between the total porosity of the scaffold and its mechanical performance. In particular, the strength of the scaffold with a porosity of 54.8% exceeded that of human bone, and it also exhibited matched stiffness. Upon analyzing the final microstructure and mechanical properties, it is evident that these scaffolds meet the necessary criteria for use as orthopedic implants.

Influence of Pre- and Post-Contouring Strategies to Downskin Sloped Surfaces in Laser Powder-Bed Fusion (L-PBF) Additive Manufacturing.

Among various metal additive manufacturing (AM) technologies, L-PBF is known for fabricating intricate components. However, due to step edges and powder particle attachments, attaining a good surface finish is challenging, especially on downskin surfaces. Contour scanning has potential to improve surface quality because such scanning may dominate the surface formation of sloped features. This study evaluates the effects of pre- and post-contouring strategies on the sloped downskin surfaces fabricated using a commercial L-PBF system with Ti6Al4V powder. L-PBF parts printed at inclination angles 30°, 45° and 60° were investigated. A double-contouring approach with varying processing conditions was employed and surface characteristics were analyzed using data acquired by white light interferometry. The average surface roughness, Sa, surface skewness, Ssk, and percentage area of powder particles attached onto surfaces were statistically evaluated. The lowest Sa obtained for pre- and post-contoured samples is 14.08 µm and 18.88 µm, respectively. For both strategies, the combination of a low laser power and a high scan speed on the interface of downskin surface and underneath powder results in smoother surfaces. However, while comparing both strategies, pre-contouring gives better surface finish for samples built at similar processing conditions, with a difference of nearly 5 µm in Sa.

Effect of TiC nano-particle on microstructure evolution and tribological behaviour of Ti6Al4V composites fabricated via spark plasma sintering

This study explores the escalating significance of lightweight and biocompatible biomedical implants with a high strength-to-weight ratio, revolutionizing critical medical applications. Despite these merits, their widespread use is hampered by poor tribological performance. Investigating the impact of TiC nanoparticles, we synthesized Ti6Al4V (Ti64) powders with varying TiC content using spark plasma sintering. The resulting nanocomposites exhibited enhanced wear resistance attributed to heightened hardness and oxidation wear resistance. Notably, at 2.5 wt% TiC content, nanohardness reached 8.99 GPa, and specific wear rate significantly decreased to 4.2 × 10−9 mm3/N-m under constant loading (20 N, 1 Hz). This reveals substantial improvements compared to Ti64 monolithic alloys, emphasizing the potential for advancing implant materials.

Simple, low-cost and high-quality fabrication of GNPs@Ti6Al4V powders for high-performance composites Inspired by pearl polishing

Uniformly dispersing graphene in matrices is challenging, which is the key to achieving high performance for metal matrix composites (MMCs) reinforced with graphene. Inspired by the process of polishing pearls, this work utilizes a vibratory polisher to mix high-purity graphite balls and Ti6Al4V powders for in-situ fabrication and homogeneous dispersion of graphene nanoplatelets (GNPs), by which the GNPs are exfoliated from the graphite balls via the friction force, and synchronously stick to the powders in one step. Whereby, the composite powders consisting of Ti6Al4V powders patched with GNPs were formed and then consolidated by spark plasma sintering. The 0.36 wt% GNPs reinforced Ti6Al4V matrix composite exhibits a tensile yield strength of 1010.8 MPa and an ultimate strength of 1075.3 MPa respectively, while possessing good ductility as high as 14.0 %. This work provides a simple and practical approach for the in-situ fabrication and uniform dispersion of GNPs in MMCs.

Vapor chemical composition in electron beam powder bed fusion using Ti–6Al–4V powder

Vapor chemical composition in electron beam powder bed fusion using Ti–6Al–4V powder

Comparison of finite element modeling approaches for Ti6Al4V porous bone implants

Additive technologies have made it possible to make a significant breakthrough in the development and production of personalized porous implants, which have clear advantages over monolithic predecessors. At the same time, engineers are faced with a number of new tasks, one of which is correct and effective numerical modeling of porous implants in the process of solving optimization problems. The study compares approaches to numerical modeling of porous titanium for bone implants, taking into account differences in the mechanical parameters of the material and the geometry of the models. The detailed geometry of the structure of 9 models is considered, for which two variants of material parameters are specified: pure Ti6Al4V alloy and experimental ones obtained for specimens printed from Ti6Al4V powder. As a proposed approach to homogenizing the structure, a continuum model of a cylinder is considered, for which the experimental properties of the specimen’s material are specified. The numerically obtained values of Young's moduli for each approach are compared with those obtained in the experiment. It has been established that when setting the properties of a pure alloy, the calculated Young's modulus exceeds the experimental one by 83–92 %. The closest thing to experiment is detailed modeling of geometry with setting the experimental properties of the material structure, while the calculated Young's modulus does not exceed the experimental one by more than 10 %. However, in this case the calculation takes from 2 to 8 hours. In the case of continuum modeling, the calculated Young's moduli exceed the calculated moduli in detailed modeling by no more than 11 %, while the calculation lasts no more than 1 minute. Based on this, it is proposed to use a continuum approach to modeling implants in the process of calculating the optimization of their shape, as an initial iteration before detailed modeling of the structure. As material properties, it is necessary to use the mechanical parameters of the structures, previously obtained from uniaxial compression experiments. Using the properties of a pure alloy will lead to results that significantly exceed the actual ones when calculating the porous structure.

Powder characterisation and the impact on part performance in electron beam melted Ti6Al4V

Metallic powder for Additive Manufacturing (AM) typically varies between different batches, while being supplied to achieve the same customer specification. In order to reduce this variation and minimise waste, batches are often mixed together in both their virgin and used form. However, the properties of bulk components must have limited variance in order to be reliably used in an industrial setting. This manuscript is focused on the analysis of Grade 5 Ti6Al4V powders (3 virgin, plus 2 blends) and the associated mechanical properties of Electron Beam Melted (EBM) AM specimens. Measurements were performed in accordance with the principles defined in the MMPDS Handbook, ESDU database, and ASTM F2924. The tensile, and fatigue properties of the EBM specimens were found to be superior when compared with Ti6Al4V properties within these standards. This demonstrated that these powders are suitable for a wide range of commercial applications, and that these blended powders (including used powders) are able to achieve these requirements. Additionally, the results provide a systematic route for powder verification and highlight the importance of adhering to standardised principles and specifications to ensure quality and reliability in metallic AM materials.

Influence of the physicochemical properties of reusable powders on the mechanical properties of Ti6Al4V manufactured via laser powder bed fusion additive manufacturing

Laser powder bed fusion additive manufacturing (L-PBF AM) technology holds notable advantages regarding raw material reusability. Nonetheless, a notable gap exists in extensive research assessing how the reuse of powders influences their intrinsic physicochemical traits as well as the mechanical attributes of the fabricated components. This study focuses on introducing an innovative approach to Ti6Al4V powder recycling in L-PBF AM, involving the incorporation of virgin spherical powder to maintain powder characteristics prior to printing. This results in sustained mechanical properties throughout seven cycles of printing (P7), with the fifth print (P5) showcasing the optimal mechanical performance (strength of 1185 MPa and elongation of 6.3%). Transmission electron microscopy (TEM) analysis was performed before and after the P5 tensile experiments，revealing a high amount of primary twinning {101¯1} in LPBF. This study offers both theoretical insights and practical validation, thereby lending substantial support to the advancement of metal AM industrialization.

Quantitative Analysis of the Physical Properties of Ti6Al4V Powders Used in a Powder Bed Fusion Based on 3D X-ray Computed Tomography Images.

The physical properties of Ti6Al4V powder affect the spreadability of the powder and uniformity of the powder bed, which had a great impact on the performance of built parts made by powder bed fusion technology. Micro-computed tomography is a well-established technique used to analyze the non-destructivity of the objects' interior. Ti6Al4V powders were scanned with micro-CT to show the internal and external information of all the particles. The morphology, particle size distribution, hollow particle ratio, density, inclusion, and specific surface area of the powder samples were quantitatively characterized, and the relationship of flowability with these physical properties was analyzed in this work. The research results of this article showed that micro-CT is an effective way to characterize these items, and can be developed as a standard method of powder physical properties in the future.