Ti6Al4V Powder Research Articles

The Effect of Various Ti6Al4V Powders on the Behavior of Particle-Reinforced Polyester Matrix Composites

In this study, recycled and commercial Ti6Al4V powder was added to polyester composites at various filling ratios by weight fraction. Three weight fractions of Ti6Al4V particles, 0%, 5%, and 10%, were chosen for study. By examining the mechanical and microstructural properties of polyester composites, the effects of the Ti6Al4V powder proportion by weight fraction and particle size parameters were investigated. With the filler loading, a 39% increase in the tensile strength of the composites was achieved. A minor decrease in flexural strength was observed at 5% filler weight fraction. The addition of the recycled Ti6Al4V powder to the polyester matrix slightly reduced the thermal conductivity of the composite over that of the neat polymer. However, the incorporation of the commercial Ti6Al4V powder fillers in the polyester matrix considerably increased the thermal conductivity of the composites, suggesting several potential uses. The presence of high levels of oxygen in the powder led to reduced thermal conductivity of the composites due to the reduction in phonon scattering.

In situ monitoring the effects of Ti6Al4V powder oxidation during laser powder bed fusion additive manufacturing

Making laser powder bed fusion (L-PBF) additive manufacturing process sustainable requires effective powder recycling. Recycling of Ti6Al4V powder in L-PBF can lead to powder oxidation, however, such impact on laser-matter interactions, process, and defect dynamics during L-PBF are not well understood. This study reveals and quantifies the effects of processing Ti6Al4V powders with low (0.12 wt%) and high (0.40 wt%) oxygen content during multilayer thin-wall L-PBF using in situ high speed synchrotron X-ray imaging. Our results reveal that high oxygen content Ti6Al4V powder can reduce melt ejections, surface roughness, and defect population in the built parts. With increasing oxygen content in the part, there is an increase in microhardness due to solid solution strengthening and no significant change in the microstructure is evident.

Microstructure and Mechanical Property of MXene-Added Ti–6Al–4V Alloy Fabricated by Laser Powder Bed Fusion

Laser powder bed fusion (L-PBF) has been utilized to prepare a high-strength titanium alloy builds using 0.3 mass% MXene-decorated Ti–6Al–4V alloy particles produced by an electrostatic self-assembly. The MXene/Ti–6Al–4V powder mixture had similar spherical morphology and powder size, while showing higher laser absorptivity as compared with the Ti–6Al–4V powders. Under high-energy laser irradiation, MXene was fully decomposed and uniformly dissolved into the Ti matrix. Microstructure observations illustrated that the MXene/Ti–6Al–4V build was completely consisted of ultrafine carbon-saturated martensite structures. Consequently, the MXene/Ti–6Al–4V build exhibited a high tensile strength of ∼1.4 GPa, attributing to the refinement of martensitic structure and the solid solution strengthening of carbon. These findings of this study may broaden the potential application of MXene and pave up the way towards the fabrication of advanced titanium parts via L-PBF.

Design and Additive Manufacturing of Acetabular Implant with Continuously Graded Porosity.

Porous structured metallic implants are preferable as bone graft substitutes due to their faster tissue integration mediated by bone in-growth and vascularization. The porous scaffolds/implants should also mimic the graded structure of natural bone to ensure a match of mechanical properties. This article presents a method for designing a graded porous structured acetabular implant and identifies suitable parameters for manufacturing the model through additive manufacturing. The design method is based on slice-wise modification to ensure continuity of gradation. Modification of the slices was achieved through the binary image processing route. A geodesic dome-type design was adopted for developing the acetabular cup model from the graded porous structure. The model had a solid shell with the target porosity and pore size gradually changing from 65% and 950 µm, respectively, in the inner side to 75% and 650 µm, respectively, towards the periphery. The required dimensions of the unit structures and the combinations of pore structure and strut diameter necessary to obtain the target porosity and pore size were determined analytically. Suitable process parameters were identified to manufacture the model by Direct Metal Laser Sintering (DMLS) using Ti6Al4V powder after carrying out a detailed experimental study to minimize the variation of surface roughness and warping over different build angles of the strut structures. Dual-contour scanning was implemented to simplify the scan strategy. The minimum diameter of struts that could be manufactured using the selected scanning strategy and scanning parameters was found to be 375 µm. Finally, the model was built and from the micro-CT data, the porosities and pore sizes were found to be closely conforming to the designed values. The stiffness of the structures, as found from compression testing, was also found to match with that of human trabecular bone well. Further, the structure exhibited compliant bending-dominated behaviour under compressive loading.

Influence of Tungsten Addition on Microstructure and Tensile Properties of Ti6Al4V Fabricated by Laser-Directed Energy Deposition

The addition of tungsten can improve the high-temperature oxidation resistance of titanium alloys. However, as its applications continue to expand, new demands are being placed on its room temperature strength. Here, we provide a dense titanium alloy with high strength by introducing proper W powders into the Ti6Al4V powders under direct energy deposition. The effect of tungsten addition on the microstructure and tensile properties of the Ti6Al4V alloy was investigated. Compared to pure Ti6Al4V, the titanium alloy with tungsten addition exhibited refined α′ martensite and β grains, which is attributable to the effect of tungsten on the structural subcooling of titanium and on the formation temperature of the α′ martensite. Owing to the synergistic strengthening effects of grain refinement and solid solution strengthening, the W-containing alloy shows a high tensile strength of 1333 MPa and yield strength of 1219 MPa, which are significantly higher than Ti6Al4V alloy’s tensile strength of 940 MPa and yield strength of 860 MPa. This approach provides a pathway for design and preparation of high-strength titanium alloys by additive manufacturing.

Simulation Analysis of Spreading Process and Electron Beam Melting of Ti6Al4V Powder

Forming process control of powder bed fusion (PBF) additive manufacturing (AM) is the key to produce high-quality qualified parts. In this paper, spreading powder process and electron-beam melting (EBM) of Ti6Al4V powder were simulated based on simulation technology, and the state of powder bed powder and melting trajectory characteristics were characterized. Firstly, the particle size distribution of Ti6Al4V powder was tested, and the particle diameter of normal distribution for simulation was determined. Then, the simulation models of spreading powder and EBM model were established. Finally, based on the simulation results, the effect of processing parameters on the quality of powder laying is analyzed, and the morphology of EBM melting trajectory is characterized.

Mechanical and wear characteristics of spark plasma sintered titanium/multilayer graphene nanocomposites

Owing to excellent mechanical properties, Titanium (Ti) alloys have been of great interest in recent years. However, due to their poor wear resistance application of these alloys is restricted in the areas involving wear and friction. To address such challenges, in the current work, multilayer graphene (MLG) reinforced titanium matrix composites have been fabricated via the spark plasma sintering process. The content of MLG in Ti6Al4V powder is varied between 0% and 1.2%. The present work explores the influence mechanism of MLG addition in Ti6Al4V by investigating fabricated nanocomposites’ microstructure, nanohardness and wear behaviour. Microstructural study reveals an in-situ reaction between a carbon source from MLG and Ti from the Ti6Al4V to form a secondary phase TiC. Moreover, due to the formation of TiC, an increase in the nanohardness value of sintered nanocomposites Ti6Al4V/1.2 wt.% MLG (5.39 GPa) was recorded when compared to fabricated Ti6Al4V alloy (3.23 GPa). Dry sliding wear tests were performed under loads of 3–7 kg. It was observed that Ti6Al4V/1.2 wt.% MLG nanocomposite shows the maximum wear resistance across various sliding velocities with a minimum wear rate of 15 × 10−6 g/m. It is evident from the results obtained that MLG plays a vital role in improving the microstructural, mechanical, and tribological properties of sintered nanocomposites.

Additive manufacturing of (TiB+TiC)/Ti6Al4V composites with tailored network reinforcement architecture

(TiB + TiC)/Ti6Al4V composites with controllable three-dimensional network structure were fabricated from mixed spherical Ti6Al4V and boron carbide (B4C) powders by laser directed energy deposition (LDED) based additive manufacturing process (AM). The (TiB + TiC) precipitates significantly refined the microstructure and aggregated at prior β grain boundaries forming network structure. The increase of the B4C content reduced the network size and the tensile performance of the composites was associated with the network size. (TiB + TiC) pinned on the network allowed specific strengthening effect, benefiting the enhancement in tensile strength of the composites, while the network structure together with α lamellae size gradient structure contributed to high uniform tensile ductility. This work demonstrates the significant potential of additive manufacturing process in creating a new class of metal matrix composites with tailored three-dimensional architecture.

Research on the consolidation and strengthening of Ti6Al4V-GO sinters

The paper presents the optimization of the sintering process by SPS of Ti6Al4V powders and the study of the impact of graphene oxide (GO) on this material. The effect of the addition of graphene oxide (GO) on Ti6Al4V was determined. Optimization of the mixing process was performed for the Ti6Al4V - xGO system. On the basis of the homogeneity of the carbon distribution, determined by X-ray spectrometry (EDS energy dispersion spectroscopy), the optimal mixing parameters were selected. In order to identify the phase boundaries between Ti6Al4V and GO, tests were performed using SEM, TEM and Raman spectrometry techniques. The appropriate selection of the parameters of the mixing and sintering process made it possible to obtain dense Ti6Al4V-GO sinters, which confirms that the addition of GO strengthens Ti6Al4V and the proposed method is an effective method of strengthening the Ti6Al4V alloy.

Optimization of processing parameters and microstructure evolution of (TiB+La2O3)/Ti6Al4V manufactured by laser melting deposition

Due to the intrinsically ultrahigh cooling rate and thermal gradient during laser melting deposition (LMD), columnar-to-equiaxed transition (CET) of grains has been a significant challenge in titanium-based alloys. In this study, two strategies, including the optimization of processing parameters and the addition of ceramics particles, were utilized to promote the CET of Ti6Al4V. The optimal processing parameters of Ti6Al4V were confirmed by response surface methodology (RSM). The width of prior β grains effectively decreases under the minimum dilution of single track. Besides, different contents of TiB2 and La2O3 were added to Ti6Al4V powder and the in situ (TiB + La2O3)/Ti6Al4V composites were manufactured using the identified optimal processing parameters. In situ TiB whiskers segregating at the grain boundaries tailor the coarse columnar to equiaxed grains with La2O3 particles dispersed in the composites. With increasing formation of the reinforcements, equiaxed grain size decreases from 23.3 to 11.9 μm. The ultimate tensile strength of the components was improved by 19.6% and 26.4% compared to that of Ti6Al4V. This work provides systematic solutions to suppress the coarse columnar grains and refine the microstructure for titanium-based alloys.

Effect of powder properties on mesoscale thermal FEM simulations of powder bed additive manufacturing

Numerous studies have used FEM simulations to assess the effects of the heat source parameters on the melt pool volume during metal powder bed additive manufacturing. However, considerable debate still exists on how to incorporate the evolution of the thermophysical properties used to describe the powder as it undergoes heating, melting, consolidation and finally solidification. For single layer studies, since powder volume is much smaller compared to the substrate volume, highly detailed, computationally expensive powder property descriptions may not provide a commensurate increase in accuracy of simulation results. This study aims to quantify the effect of powder properties on the melt pool volume created during electron beam melting of Ti6Al4V powder using predictions from a FEM-based heat conduction model. The dependence of thermal conductivity, specific heat, and density of the powder on temperature and beam power density will be studied. Additionally, the relevance of the powder properties with changing layer height and beam power and speed will also be quantified.

Comparative Life Cycle Assessment and Cost Analysis of the Production of Ti6Al4V-TiC Metal–Matrix Composite Powder by High-Energy Ball Milling and Ti6Al4V Powder by Gas Atomization

Environmental awareness and the necessary reduction in costs in industrial processes has facilitated the development of novel techniques such as Additive Manufacturing, decreasing the amount of raw materials and energy needed. The longing for improved materials with different and enhanced properties has resulted in research efforts in the Metal Matrix Composites field. These two novelties combined minimise environmental impacts and costs without compromising technical properties. Two technologies can feed Additive Manufacturing techniques with metallic powder: Gas Atomization and High Energy Ball Milling. This study provides a comparative Life Cycle Assessment of these technologies to produce one kilogram of metallic powder for the Directed Energy Deposition technique: a Ti6Al4V alloy, and a Ti6Al4V-TiC Metal–Matrix Composite, respectively. The LCA methodology is according to ISO 14040:2006, and large amounts of information on the use of raw materials, energy consumption, and environmental impacts is provided. Different impact categories following the Environmental Footprint methodology were analysed, showing a big difference between both technologies, with an 87.8% reduction of kg CO2 eq. emitted by High Energy Ball Milling in comparison with Gas Atomization. In addition, an economic analysis was performed, addressing the viability perspective and decision making and showing a 17.2% cost reduction in the conventional process.

Effect of interlayer time interval on residual stress distribution in Ti6Al4V alloy manufactured by laser powder bed fusion

A finite element is developed to study the transient temperature fields and mechanical response during laser powder bed fusion processing and multi-layer deposition of a Ti6Al4V powder. Two different powder deposition time intervals are examined. The results of our analysis reveal that short-time interlayer intervals lead to a reduction of residual von Mises stress in the produced part. A good correspondence between the experimental and numerical results was found.

Deformation behavior of metallic lattice structures with symmetrical gradients of porosity manufactured by metal additive manufacturing

Additive manufacturing of complex metallic parts is a topic of broad interest among researchers as it is imperative for critical applications like aerospace parts and biomedical implants. In this work, Functionally Gradient Lattice (FGL) structures confined within top and bottom solid skins are designed and additively manufactured (AM) by Selective Laser Melting (SLM) using Ti–6Al–4V powder. The SLM fabricated samples show the presence of a martensitic microstructure with the strut dimensions correlating with the CAD struct dimensions with slight variations in the micron regime. The struts were attached with non-melted Ti6Al4V powder particles, characteristic of the SLM process. The manufacturability and compressive performance of the struts were assessed, and the deformation behavior was studied using Digital Image Correlation (DIC) technique. The usability of the FGL structures is elucidated by comparing their uniaxial compression test results with uniform BCC structures of the same relative density (RD). The gradient structures were found to function better in both energy absorption characteristics and strength.

Microstructure and mechanical properties of TiC/Ti6Al4V nanocomposites fabricated by gas–liquid reaction laser powder bed fusion

Herein, we report a novel method for in-situ synthesis of nanometer-scaled TiC-reinforced Ti6Al4V-matrix composites (TMCs) via laser powder bed fusion (LPBF). The formation mechanism can be summarized as in-situ additive manufacturing (AM) via a gas–liquid reaction. Here, gas means the laser-induced pyrolysis methane gas (CH4) generates gaseous carbon (C) atoms/ions and liquid means that the laser beam irradiates Ti6Al4V powder to create a Ti matrix melt pool. TiC, which is the reaction product of gaseous C atom/ion with liquid Ti atom, initially undergoes nucleation and growth, and subsequently precipitates from the Ti matrix melt pool during fast LPBF cooling process. Finally, the TiC-reinforced TMCs are fabricated via a layer-wise gas–liquid reaction. With this method, three nanocomposites (Sample 2, 3 and 7) fabricated in low CH4 concentration (9 vol% and 19 vol%) exhibited good dispersion, clean interface and strong interfacial bonding between the TiC reinforcement and Ti matrix. Thus, it achieved a good combination of simultaneously high strength and high plasticity. The effects of CH4 concentration, laser power and scanning speed on the microstructures and mechanical properties including microhardness, compression behaviors and wear resistance were systematically studied. And the strengthening and toughening mechanisms of the TMCs were elucidated. The proposed in-situ AM method via the gas–liquid reaction would carve a new path for manufacturing uniformly dispersed nano-phase reinforced composites with excellent mechanical properties and complex geometries.

Microstructures and tensile properties of low-cost TiBw/Ti–6Al–4V composites by vacuum reactive hot pressing

Coarse Ti–6Al–4V powder with particle size of 150–250 μm are the by-conduct of the processing of spherical fine powder, and usually considered as waste powder. In order to reduce carbon emission during recycle process and obtain titanium-based material with low cost and good mechanical properties, the TiBw/Ti–6Al–4V composites using coarse Ti–6Al–4V powder with a particle size of 150–250 μm were designed and successfully fabricated by vacuum reactive hot pressing (VRHP). The microstructures and tensile properties of low-cost TiBw/Ti–6Al–4V composites at room temperature and elevated temperatures were studied to optimize the content of TiBw. Besides, the strengthening mechanisms were analyzed based on the analysis of plastic deformation behavior and the fracture morphologies. The results showed that the composites reinforced by 1.0 vol% TiBw exhibited superior strength and ductility synergy, with a high tensile strength of 952 MPa and an elongation of 18.4% at room temperature, which are 24.3% and 145.3% higher than that of monolithic Ti–6Al–4V alloy, respectively. In addition, the 1.0 vol% TiBw/Ti–6Al–4V composites also showed excellent mechanical properties under high temperatures. This work shows that combining the network microstructure strategy with coarse spherical powder offers a pathway to design a low-cost titanium matrix composite with promising mechanical performance.

Comparison of melt evolution and flow mechanisms of Inconel 718, Ti6Al4V, 304 stainless steel, and AlSi10Mg manufactured by laser powder bed fusion, structures, and properties after heat treatments

Process parameters and material type are the key influencing factors in laser powder bed fusion (LPBF) manufacturing. In this study, a three-dimensional high-fidelity discrete heat-flow-coupled model was developed to study the surface morphology, melt evolution, and defect formation mechanisms of four types of alloys formed using LPBF under different laser processes at the powder scale to optimize the process parameters. Four alloys were manufactured by LPBF with optimal process parameters. Multiple characterizations were adopted to disclose the effect of heat-treatment on the microstructure and mechanical properties of the as-built parts of four materials. During LPBF forming, the melts developed from continuous and semicylindrical to discontinuous and “medicine spoon”-shaped at low and high linear energy densities (LEDs), respectively. The Ti6Al4V powder bed exhibited a long trailing melt pool and acted deeper (i.e., keyhole mode). The AlSi10Mg powder bed exhibited a smaller melt pool and did not exhibit trailing (i.e., heat-transfer mode). For Inconel 718 alloy and AlSi10Mg alloy, the improvement of mechanical properties is due to the precipitation of nanoparticle phase. The equilibrium of α+β phase results in the ideal strength and plasticity of Ti6Al4V alloy. The gradual disappearance of the cellular substructure reduces the strength of 304 stainless steel, but increases the plasticity. Process parameters correlate simulations with experiments and establish a "process-structure-properties" system. This study provides insights into melt evolution and flow behavior and is a reference for selecting and optimizing materials, laser-process parameters, and heat treatment regimes in practical engineering.

Microstructure and High Temperature-Mechanical Properties of TiC/Graphene/Ti6Al4V Composite Formed by Laser Powder Bed Fusion

TiC/graphene/Ti6Al4V composites were prepared by laser powder bed fusion using graphene and Ti6Al4V powder. The differences in microstructure and high-temperature mechanical properties between the Ti6Al4V alloy and the TiC/graphene/Ti6Al4V composite were studied. The tensile and microhardness of the two materials were tested at 400 °C, 500 °C, and 600 °C; the results of the TiC/graphene/Ti6Al4V composite were 126 MPa, 162 MPa, and 76 MPa and 70 HV, 59 HV, and 61HV, respectively, higher than those of the Ti6Al4V alloy. These results happened because graphene reacted with Ti to form TiC particles, which were homogeneously distributed amongst α’ acicular martensite. The addition of graphene refined the size of the acicular α’ martensite. At the same time, the graphene and TiC particles showed a dispersion-strengthening effect. The mechanical properties of the TiC/graphene/Ti6Al4V composite were improved by the combination of fine-grain strengthening and dispersion strengthening mechanisms.

Enhancement in the fatigue resistances of triply periodic surfaces-based scaffolds

To improve the endurance limits of triply periodic minimal surface (TPMS)-based scaffolds, the post-treatment process combing hot isostatic pressing (HIP) and electropolishing (ELP) was proposed and conducted in TPMS-based scaffolds with various structures. Thus, the fatigue properties were enhanced from three aspects: changing the topological structures of TPMSs, improving surface qualities and eliminating internal defects. The stretching-dominated scaffold-new diamond (AD) and the bending-dominated scaffold-network-based gyroid (IG) were selected and their relative densities were set to 20%. These scaffolds were fabricated by electron beam melting using Ti6Al4V powders. HIP and ELP were conducted in the manufactured scaffolds. Then, compression–compression fatigue tests were performed and fatigue parameters such as fatigue life, accumulated strain rate, fatigue strength and fatigue ratio were obtained. The experimental techniques of scanning electron microscopy, microcomputer tomography, optical microscopic, X-ray diffraction and electron backscattered diffraction were carried out to characterise the surface qualities, internal defects and microstructures. The effects of topological structure and surface quality on the stress distribution on TPMS-based scaffolds under compressive loading were investigated by finite element analysis. Results show that topological structures, surface qualities and internal defects all affect the fatigue properties of TPMS-based scaffolds. Under cyclic compressive loading, the fatigue ratios of IG and AD without undergoing post-treatment are 0.11 and 0.59, respectively, while they rise to 0.26 and 0.69 after HIP and ELP. Compared with surface qualities and internal defects, topological structures influence the fatigue properties of TPMS-based scaffolds more prominently. The fatigue properties of TPMS-based scaffolds can be enhanced by the post-treatment process combing HIP and ELP, and greater improvement will be obtained for bending-dominated structures than stretching-dominated structures. Thus, manipulating the topological structures and increasing the buckling components of TPMS-based scaffolds is an effective way to obtain porous scaffolds with excellent fatigue properties under cyclic compressive loading. HIP and ELP can also be adopted to further improve their fatigue lives. The novelty of this study lies in improving the fatigue properties of TPMS-based scaffolds from the three aspects, which are changing the topology structure, improving the surface quality and reducing the internal defects, and the mechanisms of improving the fatigue properties of TPMS-based scaffolds are systematically discussed.

Evaluation of the Properties of 3D-Printed Ti Alloy Plates: In Vivo and In Vitro Comparative Experimental Study.

Titanium (Ti)-based implants play a significant role in rigid internal fixation in maxillofacial surgery. No study has reported that three-dimensional-printed Ti alloy plates (3D-Ti plates) have comprehensively excellent properties similar to standard plates (Matrix-MANDIBLE, SYNTHES, Switzerland) (Synthes-Ti plates). In this work, we manufactured 3D-Ti plates by selective laser melting with Ti6Al4V powder. The surface morphology, mechanical properties, and bone-plate contact rate of the 3D-Ti plates and the Synthes-Ti plates were characterized and compared via electron microscopy, atomic force microscopy, Vickers hardness test, three-point bending test, and software calculation. Human bone marrow stromal cells (HBMSCs) were cultured on the plates to test their biocompatibility. Importantly, the 3D-Ti plates were placed into a mandibular fracture model to assess the effect of medical application for 4 and 24 weeks. The 3D-Ti plates were demonstrated to have similar biocompatibility and stability for rigid internal fixation with the Synthes-Ti plates, lower roughness (106.44 ± 78.35 nm), better mechanical strength (370.78 ± 1.25 HV10), and a higher bone-plate contact rate (96.9%). These promising results indicate the feasibility of using 3D-Ti plates for irregular shapes and complex anatomical structures in a clinical context.