bluuebunny/crossref_metadata_2025 huggingface dataset:
Adsorption driven formate reforming into hydride and tandem hydrogenation of nitrophenol to amine over PdOx catalysts
Authors: Zhu Xiaohui , Liang Shipan , Chen Shuang , Liu Xiangdong , Li Renhong
Published: October 2020

Due to their high toxicity and non-biodegradability, efficient reduction of nitroarenes to amines is of great practical importance, yet it still remains a significant challenge.
Enhanced triplet–triplet annihilation upconversion by photonic crystals and Au plasma resonance for efficient photocatalysis
Authors: Fang Jiaojiao , Chen Yukai , Zhu Cheng , Li Xue , Wang Wei , Lu Chunhua , Ni Yaru , Fang Liang , Xu Zhongzi
Published: October 2020

The coupling electromagnetic field of AVS structure effect and AuNPs LSPR can synergistically improve TTA-UC efficiency, thereby enhancing the photocatalytic activity of g-C3N4@CdS.
Quinoline- and isoquinoline-derived ligand design on TQEN (N,N,N′,N′-tetrakis(2-quinolylmethyl)ethylenediamine) platform for fluorescent sensing of specific metal ions and phosphate species
Authors: Mikata Yuji
Published: October 2020

Utilizing the unique metal-binding and fluorescent properties of methoxy-substituted (iso)quinolines, varieties of fluorescent probes were developed from TQEN (N,N,N′,N′-tetrakis(2-quinolylmethyl)ethylenediamine) structure.
Amphiphobic polyHIPEs with pH-triggered transition to hydrophilicity–oleophobicity for the controlled removal of water from oil–water mixtures
Authors: Li Xiaomin , Zhang Tao , Xu Zhiguang , Chi Huanjie , Wu Zhu , Zhao Yan
Published: October 2020

Amphiphobic polyHIPEs with pH-triggered transition to hydrophilicity–oleophobicity were templated from high internal phase emulsions for the controlled removal of water from oil–water mixtures.
Substituted glycolides from natural sources: preparation, alcoholysis and polymerization
Authors: Nifant'ev Ilya E. , Shlyakhtin Andrey V. , Bagrov Vladimir V. , Tavtorkin Alexander N. , Komarov Pavel D. , Churakov Andrei V. , Ivchenko Pavel V.
Published: October 2020

Herein we present a comparative study of substituted glycolides MeGL, iPrGL, iBuGL, BnGL, PhGL and MePhGL, synthesized from natural sources and polymers therefrom.
Hierarchical MoP/NiFeP hybrid hollow spheres as highly efficient bifunctional electrocatalysts for overall water splitting
Authors: Lin Lifeng , Chen Min , Wu Limin
Published: October 2020

Herein, we report a facile synthesis of novel hierarchical MoP/NiFeP hybrid hollow spheres (MoP/NiFeP HSs) as an electrocatalyst for the first time.
Converting waste textiles into highly effective sorbent materials
Authors: Nasri-Nasrabadi Bijan , Byrne Nolene
Published: October 2020

Activated carbon fibres with a tubular structure and exfoliated surface were produced utilizing cotton textile waste as the precursor.
Hydroxychalcone dyes that serve as color indicators for pH and fluoride ions
Authors: Du Yanqing , Liang Fengying , Hu Mixia , Bu Ren , Wang Meiling , Tsuda Akihiko , Eerdun Chaolu
Published: October 2020

A chalcone diol shows visible color changes upon sensing pH of water and fluoride ions in an organic solvent.
Simultaneous determination of 11 antiseptic ingredients in surface water based on polypyrrole decorated magnetic nanoparticles
Authors: Zhang Mengyan , Lian Kaoqi , Ai Lianfeng , Kang Weijun , Zhao Tangjuan
Published: October 2020

Polypyrrole decorated magnetic nanoparticles Fe3O4@PPy were synthesized by a simple and efficient chemical oxidative polymerization method and used for the extraction of 11 antiseptic ingredients in surface water.
Oligo-glycerol based non-ionic amphiphilic nanocarriers for lipase mediated controlled drug release
Authors: Parmanand  , Mittal Ayushi , Singh Abhishek K. , Aarti  , Achazi Katharina , Nie Chuanxiong , Haag Rainer , Sharma Sunil K.
Published: October 2020

A new series of oligo-glycerol based amphiphiles have been synthesized for drug delivery.
Effect of external pressure on the release of methane through MFI zeolite nanochannels
Authors: Cheng Xu , Li Zhigang , He Ya-Ling
Published: October 2020

In this work, the effects of external pressure on the release of methane through zeolite nanochannels are studied through molecular dynamics (MD) simulations.
Insulin amyloid polymorphs: implications for iatrogenic cytotoxicity
Authors: Yuzu Keisuke , Lindgren Mikael , Nyström Sofie , Zhang Jun , Mori Wakako , Kunitomi Risako , Nagase Terumasa , Iwaya Keiichi , Hammarström Per , Zako Tamotsu
Published: October 2020

Structural polymorphism of insulin amyloids in vivo can be recognized using novel amyloid specific fluorescent probes, pFTAA and BTD21.
Selective inhibition of the K+ efflux sensitive NLRP3 pathway by Cl− channel modulation
Authors: Swanton Tessa , Beswick James A. , Hammadi Halah , Morris Lucy , Williams Daniel , de Cesco Stephane , El-Sharkawy Lina , Yu Shi , Green Jack , Davis John B. , Lawrence Catherine B. , Brough David , Freeman Sally
Published: October 2020

The NLRP3 inflammasome regulates production of the pro-inflammatory cytokines interleukin-1β (IL-1β) and IL-18, and contributes to inflammation exacerbating disease.
A serological aptamer-assisted proximity ligation assay for COVID-19 diagnosis and seeking neutralizing aptamers
Authors: Liu Ran , He Lei , Hu Yuansheng , Luo Zhaofeng , Zhang Jingjing
Published: October 2020

A versatile aptamer-assisted proximity ligation system improves diagnosis of COVID-19, and allows the evaluation of potential neutralizing aptamers.
Photocatalytic redox-neutral hydroxyalkylation of N-heteroaromatics with aldehydes
Authors: Fuse Hiromu , Nakao Hiroyasu , Saga Yutaka , Fukatsu Arisa , Kondo Mio , Masaoka Shigeyuki , Mitsunuma Harunobu , Kanai Motomu
Published: October 2020

Hydroxyalkylation of N-heteroaromatics with aldehydes was achieved using a binary hybrid catalyst system comprising an acridinium photoredox catalyst and a thiophosphoric acid organocatalyst.
Combining alkali metals and zinc to harness heterometallic cooperativity in cyclic ester ring-opening polymerisation
Authors: Gruszka Weronika , Lykkeberg Anna , Nichol Gary S. , Shaver Michael P. , Buchard Antoine , Garden Jennifer A.
Published: October 2020

Cooperative heterotrimetallic Na/Zn2 and K/Zn2 complexes combine the excellent activities and control of the homometallic analogues, giving “best of both” in cyclic ester ring-opening polymerisation.
Catalytically propelled 3D printed colloidal microswimmers
Authors: Doherty Rachel P. , Varkevisser Thijs , Teunisse Margot , Hoecht Jonas , Ketzetzi Stefania , Ouhajji Samia , Kraft Daniela J.
Published: October 2020

3D microprinting allows the preparation of colloidal microswimmers with unlimited shape complexity furthering the understanding of out-of-equilibrium phenomenon.
SCaLAr – A surrounding spherical cap loudspeaker array for flexible generation and evaluation of virtual acoustic environments
Authors: Pausch Florian , Behler Gottfried , Fels Janina
Published: October 2020

Introduction: Surrounding spherical loudspeaker arrays facilitate the application of various spatial audio reproduction methods and can be used for a broad range of acoustic measurements and perceptual evaluations.

Methods: Installed in an anechoic chamber, the design and implementation of such an array of 68 coaxial loudspeakers, sampling a spherical cap with a radius of 1.35 m on an equal-area grid, is presented. A network-based audio backbone enables low-latency signal transmission with low-noise amplifiers providing a high signal-to-noise ratio. To address batch-to-batch variations, the loudspeaker transfer functions were equalised by individually designed 512-taps finite impulse response filters. Time delays and corresponding level adjustments further helped to minimise radial mounting imperfections.

Results: The equalised loudspeaker transfer functions measured under ideal conditions and when mounted, their directivity patterns, and in-situ background noise levels satisfy key criteria towards applicability. Advantages and shortcomings of the selected decoders for panning-based techniques, as well as the influence of loudspeaker positioning errors, are analysed in terms of simulated performance metrics. An evaluation of the achievable channel separation allows deriving recommendations of feasible subset layouts for loudspeaker-based binaural reproduction.

Conclusion: The combination of electroacoustic properties, simulated sound field synthesis performance and measured channel separation classifies the system as suitable for its target applications.
Advances and Breakthroughs in Titanium forgings for critical structural parts
Authors: Lecadet J. , Forestier R. , Delaborde P.
Published: October 2020

Assuming the high level of properties and reliability of titanium forgings, strong drivers of research and development for forgings are the pressure on cost, the buy to fly ratio reduction and the life cycle. This presentation discusses the potential of optimizations to address these challenges. The first way to concretely answer the question of the cost and of the life cycle is the recycling of manufacturing scrap and end-of-life products, using the concept of circular economy and implementing a short loop from end user to melters. This is a considerable opportunity to mitigate the risks related to the supply of primary material and to the erratic fluctuations of raw material prices.

The second step to optimize both the added value and the material consumption consists in adapting accurately the melting and ingot conversion processes to the actual needs of the application and the subsequent transformation processes.

Considering the close die forging step, the use of the concept of Design for forging has also a great potential to optimize the cost and the functions of the forgings. Near Net Shape Forging of titanium, using high temperature close die forging is a great opportunity to make a breakthrough in terms of buy to fly ratio. In addition to all these improvements, the use of high-power hydraulic presses is a key element to take full advantage of them and to manufacture large critical parts with more functions.

All together these levers could provide drastic cost reductions, and a considerable reduction in the environmental impact, keeping the advantages of titanium forgings in terms of metallurgical integrity, residual stresses and properties. The implementation of these improvements will require continuous efforts of development from the whole titanium supply chain, and collaboration between integrated titanium forgings suppliers and the OEMs.
HIGH TEMPERATURE OXIDATION OF TI-6AL-4V ALLOY FABRICATED BY ADDITIVE MANUFACTURING. INFLUENCE ON MECHANICAL PROPERTIES
Authors: CASADEBAIGT Antoine , MONCEAU Daniel , HUGUES Jonathan
Published: October 2020

Titanium alloys, such as Ti-6Al-4V alloy, fabricated by additive manufacturing processes is a winning combination in the aeronautic field. Indeed, the high specific mechanical properties of titanium alloys with the optimized design of parts allowed by additive manufacturing should allow aircraft weight reduction. But, the long term use of Ti-6Al-4V alloy is limited to 315 °C due to high oxidation kinetics above this temperature [1]. The formation of an oxygen diffusion zone in the metal and an oxide layer above it may reduce the durability of titanium parts leading to premature failure [2, 3]. In this study, Ti-6Al-4V alloy was fabricated by Electron Beam Melting (EBM). As built microstructure evolutions after Hot Isostatic Pressure (HIP) treatment at 920 °C and 1000 bar for 2h were investigated. As built microstructure of Ti-6Al-4V fabricated by EBM was composed of Ti-α laths in a Ti-β matrix. High temperature oxidation of Ti-6Al-4V alloy at 600 °C of as-built and HIP-ed microstructures was studied. This temperature was chosen to increase oxidation kinetics and to study the influence of oxidation on tensile mechanical properties. In parallel, two other oxidation temperatures, i.e. 500 °C and 550°C allowed to access to the effect of temperature on long-term oxidation.
Impact of process parameters and heat treatment on mechanical properties of Ti64 LBM
Authors: BERNARD Pierre
Published: October 2020

Titanium is a very useful material for aerospace part manufacturing due to its mechanical properties and its lightness. Additive layer manufacturing (ALM), and amongst it Laser Beam Melting (LBM), is a new tool to manufacture parts that have a certain degree of complexity. It allows for the reducing of lead time, as well as reduces the development cycle. The aerospace industry is using more and more this tool to manufacture parts, either for development or for production.

With that in mind, Ti64 was developed in Vernon in order to manufacture parts for the Ariane propulsion engines. Certain parameters have been modified from the standard EOS set of parameters in order to gain in elongation at cryogenic temperatures. Also, a special work was performed in order to define the best heat treatment for Ariane’s applications. The main parameters adjusted were linked to the baseplate temperature during building, as well as the use of HIP. The gain was not only on elongation, but also on porosity rate and mechanical properties (tensile, fatigue) at cryogenic temperatures. Other parameters are being studied today in order to increase productivity.
An Overview of Cold Spray Additive Technology in Australia for Melt-less Manufacture of Titanium
Authors: Zahiri Saden H. , Gulizia Stefan , Prentice Leon
Published: October 2020

The difficulty in significantly reducing the cost of titanium products is partly related to the high cost of manufacturing. This includes additive manufacturing; e.g. Electron Beam Melting (EBM) and Selective Laser Melting (SLM), as well as traditional approaches that are based on a melting process. In particular, the cost of titanium powder has placed limits on the application of additive manufacturing approaches that involve melting to broader commercial applications beyond military, aerospace and implants. More than a decade ago, Australia adopted cold spray technology as a meltless additive manufacturing technique to fabricate titanium through a strategic initiative at Commonwealth Scientific and Industrial Research Organisation (CSIRO). The high deposition rate, ~100 times faster than the other additive technologies, and the solid state deposition were amongst the rationales for investment in cold spray technology. A combination of carefully designed experiments and sophisticated 3D models were developed to assess performance of the current industrial-scale cold spray systems for commercial clients. The success and challenges of this solid state deposition technology will be detailed with a focus on real industrial impact. The future development of melt-less titanium manufacturing using cold spray will be discussed with consideration of commercial and environmental benefits.
SERIES PARTS MANUFACTURING BY INFRARED SUPERPLASTIC FORMING WITH NUMERICAL TECHNIQUES FOR THERMAL REGULATION
Authors: Elise LAMIC , Damien MAUDUIT , Fabien NAZARET , Rémi GILBLAS , Thomas POTTIER , Thierry CUTARD
Published: October 2020

Materials used for Superplastic forming (SPF) are mainly titanium alloys which are good candidates to produce lightweight complex-shaped components for high performance aerospace applications. SPF process has limitations because it involves a high-temperature furnace with poor heat efficiency and expensive tooling with low management flexibility. Enhancing this manufacturing process is a major challenge for the aerospace industry which is facing to important production ramp-up and cost reductions. Direct heating combined with tool heat management result in significant savings of SPF process: production time savings by drastically reduce the heating time, reduction of maintenance costs and energy savings by significant heat efficiency improvement.

Aurock developed direct heating by Infrared emitters and succeed in forming series 1.5x1m² Ti6Al-4V blanks. A key point with this new technology is to ensure a homogeneous blank temperature all along the forming. This point is achieved thanks to lamp power modulations and numerical techniques to secure the blank thermal regulation with a full radiative flux control at different forming stages. Results obtained are stable and repeatable regarding to dimensional criteria, post-forming thicknesses distribution and microstructure. Numerical predictions are in very good agreement with the experimental results, enabling robust machine setup for series Infrared SPF parts production.
From the fatigue properties of Ti6Al4V produced by ALM selective laser melting process to the mechanical design of an aeronautical part
Authors: Edy François , LE Viet-Duc , BIERE Claudia , Perez Monica , Pessard Etienne , Morel Franck
Published: October 2020

Selective laser melting SLM is investigated through a study of redesign and characterization of an aeronautic part made of titanium Ti6Al4V. The part must ensure an excellent static and fatigue behaviour. The methodology developed hereby follows 3 main steps: First, the influence of laser power, laser speed and hatch distance on the amount/rate of porosity is performed to define optimized process parameters. Then, the influence of building process strategy, i.e. building direction or as-built surface roughness on the static and fatigue behaviour are studied and understood by following a vast experimental campaign. Obtained properties are finally used in a topology optimization study to find the best compromise between part weight and fatigue behavior . 3 prototypes of simulated part are produced and then characterized. Fatigue tests are conducted on the component and confirm the fatigue design proposed. Obtained results are encouraging and illustrate the fatigue design optimization of a complex Additive Manufacturing component.
Numerical simulation of Rapid Additive Forging (RAF) process
Authors: Depradeux Lionel , Robitaille Corentin , Duval Gilles , Eckenfelder Luc , Locatelli Camille
Published: October 2020

The Rapid Additive Forging (RAF) process is a Direct Energy Deposition (DED) Additive Manufacturing (AM) process, based on the deposition of a Titanium alloy on a substrate plate. This process has been developed for the production of Titanium parts of aeronautic components. In this study, a Finite Element (FE) numerical simulation methodology has been established to perform a fast analysis of the RAF process, including full 3D-transient thermal-metallurgical and mechanical numerical simulations. Thus, residual stresses and distortions caused by the process can be estimated. Different modelling strategies have been compared in order to find a balance between computation time and accuracy. Analyses include the effects of phase transformations in the Titanium alloy. First analyses have been performed on a simple geometry of welding wall. The influences of the material activation modelling strategy on the thermal and mechanical results have been investigated. The effects of phase transformations on residual stresses and distortions are also discussed.

Then a specimen with a more complex geometry has been considered in the analysis, including the effect of different deposition paths. A full 3D simulation of the whole deposition process has been compared with several simplified computation procedures, including a reduction of the number of layers considered in the simulation.
The Role of Oxygen in α2 Formation in the Titanium Model Alloy Ti-7Al
Authors: Gardner H. M. , Radecka A. , Rugg D. , Armstrong D. E. J. , Moody M. P. , Bagot P. A. J.
Published: October 2020

The mechanical and microstructural response of a model Ti-7wt.%Al alloy doped with 500 wppm oxygen has been examined in detail as a function of ageing. Three ageing conditions, ice-water quenched, and aged at 550 oC for 10 or 49 days were examined in detail as a function of ageing. Nanoindentation was used to measure hardness as a function of ageing, while Atom Probe Tomography (APT) also revealed α2 precipitation in the aged samples. The partitioning pReference of oxygen to the α matrix instead of the α2 precipitates has been directly measured.
Failure investigation as a route to improving integrity of titanium alloys in service
Authors: Collins C. , Dear F.F. , Rugg D. , Dye D.
Published: October 2020

Increasing demands on titanium alloys in aerospace applications have driven a push towards deeper understanding of their behaviour in service. This extends from component performance during planned operation to damage mechanisms and how parts may ultimately fail. Investigation of damage and failure requires a comprehensive framework of techniques in order to identify a root cause, and further the understanding of failure mechanisms. It is crucial to defining and improving component lifetimes via a design optimisation feedback loop. This paper presents an overview of the techniques used in state-of-the-art industrial titanium alloy failure investigation, highlighting the inherent reciprocal links to frontline research and the need for constant innovation.
Role of refractory elements in near-alpha titanium alloys on high temperature mechanical properties
Authors: Huvelin Z. , Gouroglian C. , Horézana N. , Naka S.
Published: October 2020

The effect of Tungsten (W), Tantalum (Ta) and simultaneous addition of Germanium (Ge) and Silicon (Si) on the microstructure evolution, tensile and creep properties of the near-alpha alloy Ti-5.7Al-3.9Sn-3.7Zr-0.7Nb-0.5Mo-0.35Si-0.05C have been investigated at high temperatures up to 650°C. Microstructural characterizations following solution treatment at 1050°C for 2 hours with oil quenching and aging treatment at 700°C for 2 hours followed by air cooling, highlighted that the additions of refractory elements such as W and Ta led to a decrease of both the volume fraction of the primary alpha phase (ap) and its average size. Tensile tests performed up to 650°C revealed a significant improvement in tensile strength with additions of W and Ta, even though a decrease of ductility has been also detected. Creep tests carried out at 600°C under a constant stress of 200 MPa pointed out that, refractory elements, Ge and Si have a beneficial effect on both primary and steady-state creep strain rates.
Effect of silicon on creep properties of titanium 6Al-2Sn-4Zr-2Mo alloy
Authors: Anti M-L , Collado Ciprés V , Mouzon J , Åkerfeldt P. , Pederson R
Published: October 2020

The alloy Ti-6Al-2Sn-4Zr-2Mo is a titanium alloy for elevated temperatures often used in aerospace applications. Minor additions of silicon have proven to improve the creep resistance of this alloy. In this work, three different amounts of silicon (0.015, 0.07 and 0.162 wt% Si) were added to cast Ti-6242 and creep tests were performed at different temperatures and loads. Creep resistance increased significantly with silicon addition by means of silicide precipitation hindering dislocations movement. Silicon rich nanoparticles in the microstructure were detected and their effect on creep resistance was investigated. The instruments used in this study were light optical microscope (LOM) and scanning electron microscopy (SEM).

Precipitates larger than 150 nm were found to be located heterogeneously in the microstructure, whereas smaller precipitates, ranging from 20-100 nm were homogeneously spread in the material. All silicides were predominantly situated next to the beta-phase in the alloy, either at the prior-beta grain boundaries or the beta-phase in between the alpha-colonies.
The Bonding of Additive Manufactured Ti-6Al-4V via the Powder Interlayer Bonding (PIB) Process
Authors: Davies P. , Davies H. , Marchisio S.
Published: October 2020

Powder interlayer bonding (PIB) is a novel joining technique. The technique has been developed to facilitate high integrity repairs of aerospace components, manufactured from titanium alloys commonly employed in the aerospace industry. The PIB technique utilises an interlayer between the two faying surfaces. In this study heating was supplied via induction, enabling a bond to be created in an inert atmosphere, shielding the fusion zone from oxidation during bonding. The PIB technique proved capable of producing high integrity bonds in additive manufactured Ti-6Al-4V, where approximately 85% of the strength of the alloy is retained after bonding. Advantages of this technique over more established joining methods such as tungsten inert gas (TIG) welding and plasma arc (PA) welding include a narrow fusion zone and localised heating. It is believed that PIB can compete against these more mature techniques, providing a technique suitable for joining a range of alloys found in the aerospace industry.
Control of crystallographic orientation by metal additive manufacturing process of β-type Ti alloys based on the bone tissue anisotropy
Authors: Nakano Takayoshi , Ishimoto Takuya , Matsugaki Aira , Hagihara Koji , Koizumi Yuichiro , Ozasa Ryosuke
Published: October 2020

Variation in the scanning strategy for β-type Ti alloys during additive manufacturing (AM) enables the fabrication of a singlecrystal-like microstructure possessing a crystallographic texture, in which the low-Young’s modulus-<100> direction is aligned along a specific direction. Thus, metal biomaterial with low elasticity, comparable to the bone Young’s modulus, can be developed by AM, which will contribute to suppress the stress shielding of bone and prevent degradation of bone tissue anisotropy.
Second-generation Titanium alloys Ti-15Mo and Ti-13Nb-13Zr: A Comparison of the Mechanical Properties for Implant Applications
Authors: Brunke Florian , Siemers Carsten , Rösler Joachim
Published: October 2020

Due to their outstanding mechanical properties, excellent corrosion resistance and biocompatibility titanium and titanium alloys are the first choice for medical engineering products. Alloys currently used for implant applications are Ti-6Al-4V (ELI) and Ti-6Al-7Nb. Both alloys belong to the class of (α+β)-alloys and contain aluminium as an alloying element. Aluminium is cytotoxic and can cause breast cancer. In addition, the stiffness of (α+β)-alloys is relatively high which can lead to stress shielding, bone degradation and implant loss. For this reason, second-generation titanium alloys like Ti-15Mo (solute-lean metastable β-alloy) and Ti-13Nb-13Zr (β-rich (α+β)-alloy) have been developed. However, their application in medical implants is limited due to a relatively low strength.

Therefore, in the present study, the mechanical properties of Ti-15Mo and Ti-13Nb-13Zr have been optimised by thermomechanical treatments to achieve high strengths combined with low stiffnesses. Different phase compositions have been used, namely, α-, β- and ω-phase in Ti-15Mo and α-, β- and αʺ-phase in Ti-13Nb-13Zr. For Ti-15Mo, the required mechanical properties’ combination could not be achieved whereas Ti-13Nb-13Zr showed high strength and a low Young’s modulus after a dedicated thermo-mechanical treatment. This makes the latter alloy a good option for replacing the (α+β)-alloys in implant applications in the future.
Achieving high strength and low Young’s modulus by controlling the beta stabilizers content in Ti-Nb-Ta-Zr-O alloys
Authors: Preisler D. , Stráský J. , Janovská M. , Becker H. , Harcuba P. , Janeček M.
Published: October 2020

High strength and low Young’s modulus is the desired combination of mechanical properties for the endoprostheses material. Metastable beta titanium alloys are promising materials for this application. In this study, four Ti-xNb-6Ta-7Zr-0.7O (wt.%) alloys were prepared where Nb content ranged from 26 to 35 wt. %. All alloys contained pure beta phase. The high oxygen content causes high microhardness (330 HV), hence also the strength, while decreasing content of Nb leads to lower electrons per atom (e/a) ratio. The e/a ratio affects the Young’s modulus which is highest (76 GPa) in Ti-35Nb-6Ta-7Zr-0.7O alloy with e/a=4.31 and the lowest (64 GPa) in Ti-26Nb-6Ta-7Zr-0.7O with e/a=4.24. Such evolution of Young’s modulus is in accordance with existing literature data, however, in comparison with other works, the Ti-26Nb-6Ta-7Zr-0.7O alloy shows double microhardness when compared to alloys with similar Young’s modulus. Therefore, the approach of using controlled oxygen content for alloy design is very promising for development of biocompatible metastable beta Ti alloy for endoprostheses production.
Phase transformations during continuous heating: effect of Sn addition on the microstructure of Ti-13Mo alloy
Authors: de Mello M.G. , da Costa F.H. , Caram R.
Published: October 2020

The addition of Sn to the Ti-Mo system can diminish the formation of ω phase and slow down the precipitation kinetics of α phase due to the low atomic diffusivity of Sn atoms in Ti. To explore α phase precipitation in Ti-13Mo and Ti-13Mo-6Sn (wt.%) alloys, differential scanning calorimetry (DSC) was applied using different heating rates to determine ω phase dissolution, α phase precipitation and β transus temperatures. The DSC results were then used to determine the aging heat treatment temperatures. Samples were heat-treated at 600 °C for 1 h and 24 h to examine microstructure features. The addition of Sn to Ti-13Mo alloy was found to increase the β phase lattice parameter, increasing β transus temperatures and resulting in microstructures with heterogeneous and coarser α phase precipitation.
Correlation between susceptibility to environment-assisted cracking of super-elastic TiNi alloy and the states and their amount of hydrogen in it
Authors: Haruna Takumi , Morihashi Daiki , Hirohata Youhei
Published: October 2020

Susceptibility to environment-assisted cracking (EAC) of super-elastic TiNi alloy has been correlated with the states and their amount of hydrogen in the material. The TiNi alloy specimen was immersed in sulfate solutions at a given pH, and a giving cathodic potential was applied to it for 13 ks to absorb hydrogen into it. The specimen was subjected to X-ray diffraction (XRD) test to detect hydride, and to thermal gas desorption spectroscopy (TDS) test to determine the state and its amount of hydrogen in it. In the case that a potential of -0.5 VAg/AgCl was applied to the specimen in the solution of pH 3, the XRD detected no hydride on it. Whereas, application of -1.5 VAg/AgCl was induced formation of hydride. The TDS indicated that the specimen treated at -0.5 VAg/AgCl involved hydrogen desorbing around 810 K, and the one at -1.5 VAg/AgCl involved hydrogen desorbing around 500 as well as 810 K. Therefore, it was suggested that the hydrogen desorbing at lower and higher temperatures obtained by the TDS were of hydride state and solid-solution state, respectively. The specimens treated under various conditions were analyzed by the same way as mentioned before, and an amount of the hydrogen in each state as well as a cathodic charge density applied to the specimen were obtained to be correlated. A logarithm of the amount of the hydrogen in the each state increased almost linearly with an increase in a logarithm of a charge density. Susceptibility to the EAC of the material suddenly increased around a charge density of 0.025 MC·m-2, and the charge density was considered to induce the amounts of hydrogens in hydride and solid-solution state of 10 and 100 mass ppm, respectively.
Suppressing the oxygen ingress into Ti-alloys by a one-step Al- plus F-treatment
Authors: Donchev Alexander , Galetz Mathias
Published: October 2020

Oxygen ingress into technical Ti-alloys during high temperature exposure in oxygen containing environments leads to an enriched surface zone due to the high oxygen solubility in titanium. This affected zone is known as alpha case and is embrittled compared to the substrate material. Therefore, the operating temperature of these alloys is limited. An enrichment of Al in the surface zone of Ti-alloys leads to an improvement by the formation of intermetallic TixAly-phases with decreased oxygen solubility. This one-step Al-enrichment plus a F-treatment is proposed for the formation of a continuous stable alumina scale which prevents oxygen inward diffusion. In this paper the results of high temperature exposure tests in air of technical Ti-alloys are presented without any treatment and treated with Al-enrichment including fluorination. Post experimental investigations such as SEM reveal the formation of thin alumina layers on treated samples. Hardness measurements confirm that no embrittlement was observed for the treated samples while untreated specimens show increased hardness values in the subsurface zone corresponding with the oxygen inward diffusion profile.
The nitrogen effect on the oxidation behaviour of Ti6242S titanium-based alloy: contribution of atom probe tomography
Authors: Dupressoire C. , Descoins M. , Vande Put A. , Mangelinck D. , Emile P. , Monceau D.
Published: October 2020

At high temperatures under oxidizing environments, titanium-based alloys form an oxide scale and dissolve large amount of oxygen in their metallic matrix. Oxygen dissolution is a cause of embrittlement. Nitrogen is a secondary oxidant, which also dissolves in titanium during oxidation in air. Oxidation experiments of Ti-6Al-2Sn-4Zr-2Mo-0.1Si titanium-based alloy at 650 °C for 1000 h in synthetic air (20%O2- 80%N2) and in a mixture of 20%O2-80%Ar, showed that nitrogen reduces both oxide scale growth and oxygen dissolution. Atom probe tomography revealed that nitrogen effect is due to the formation of an interfacial layer of nitride Ti2N but also to the formation of a nitrogen rich a-Ti-based solid solution, which both act as difiusion barriers for oxygen because of their low oxygen solubility.
Effect of Microstructure of Surface Layer in Steel Vessel Used for Sponge Titanium Manufacturing on Fe Elution
Authors: Watanabe Meiji , Taki Kazuhiro , Yamaguchi Masanori , Inoue Yosuke
Published: October 2020

To make clear factors affecting Fe elution into molten Mg during sponge titanium production process and reasons why Fe elution from the steel vessel in the first use is high while it considerably reduces in the second use in the actual mill, immersion experiments into molten Mg at 950ºC were conducted using specially designed specimens simulating the first and the second uses of the vessel, and microstructure change of the steel during the use was investigated in detail. TiFe, TiFe2 and Ti-diffused steel layers formed on the surface of the steel specimen after the treatment similar to the first use of the vessel. The outermost portion of Ti-diffused steel contained 3mass% Ti, which should have transferred to the α phase at this temperature. Fe elution from TiFe and TiFe2 was almost zero, while Fe elution from Fe-3mass%Ti was 1/4 of that from the unused steel. By taking the information on the phases appeared on the surface of the actual vessel into account, Fe elution from the vessel at the second use was estimated as 1/16 of that at the first use, which is well consistent with the value in the actual production mill.
Atomization of Ti-64 alloy using the EIGA process: comparison of the characteristics of powders produced in labscale and industrial-scale facilities
Authors: Drawin Stefan , Deborde Agathe , Thomas Marc , Pierronnet Michel , Sasaki Layla , Delfosse Jérôme , Godde Olivier
Published: October 2020

Titanium alloy powders, mostly the Ti-64 alloy with composition Ti-6Al-4V (wt.%), are extensively used for biomedical and high-demanding applications, e.g. in aeronautics. Advanced powder metallurgy processes like additive manufacturing are strong drivers for the production of high quality powders, insuring a good rheological behavior, a low porosity level in the parts and an adequate roughness. Ideally, fine spherical particles with no volume and surface defects are aimed at.

Inert gas atomization is a process that is able to produce clean powders for such applications, especially for AM. To avoid the chemical reaction of titanium with the commonly used alumina crucibles, a crucible-free configuration has been designed in the EIGA process (Electrode induction melting Inert Gas Atomization). Two EIGA facilities are currently available in France for R&D purposes: a one-liter (nominal rod diameter/length (mm): 50/500) labscale facility at ONERA and an eight-liter capacity (100/1000) industrial-scale facility at the MetaFensch Institute. Using the smaller facility to screen and optimize atomization parameters and transfer them to the bigger facility is a tempting approach. This communication will show the characteristics of Ti-64 powders produced in both facilities, in terms of particle shape, particle size distribution, presence of satellites and porous particles.
Advancement of Plasma Cold-Hearth Melting for Production of Gamma Titanium Aluminide Alloys within Arconic
Authors: Crist Ernie , Jena Birendra , Jacques Michael , Dahar Matt , Li Don , Sun Fusheng
Published: October 2020

Utilization of gamma titanium aluminide alloys in aerospace and automotive/industrial applications has placed significant demand on melting sources for products to be used in cast, wrought, and direct-machining applications. There is also an increased demand for input stock used in gas atomization of powders. Current technologies used in ingot manufacturing include plasma arc melting, vacuum arc melting, and induction skull melting + centrifugal casting. Subsequent processing may include forging, re-melting + casting, or machining directly into components. Over the past six years, Arconic Engineered Structures has developed a robust melting method using plasma cold-hearth melting technology, including the design and implementation of a new 3-torch system to produce Ti-48-2-2 cast bars. General discussions concerning plasma cold-hearth melting, manufacturing challenges, and metallurgical attributes associated with cast Ti-48-2-2 bars will be reviewed. Emphasis will be on understanding the impact of hot isostatic pressing on internal voids, residual stress cracking and resulting mechanical properties.
Improvement of high temperature performance of titanium matrix composites by constructing hierarchical microstructure
Authors: Huang Lujun , Geng Lin
Published: October 2020

The improvement of mechanical properties must be achieved by designing and constructing more suitable microstructure, such as hierarchical microstructure and nano microstructure. In order to significantly enhance the creep resistance of titanium alloys, one two-level hierarchical microstructure with micro-TiB whiskers (TiBw) and nano Ti5Si3 reinforcements were constructed to form the modified composites by powder metallurgy combining with in-situ synthesis and precipitation. The micro TiBw reinfrocement were in-situ synthesized around titanium matrix particles, which formed the first scale network microstructure. The nano Ti5Si3 particle were precipitated and distributed in the beta phase around alpha phase which formed the second network microstructure. The results showed that the high temperature strength has been significantly enhanced. The tensile strength at 550oC for Ti6Al4V matrix composites is increased to 1050MPa. Moreover, the creep rate of the modified Ti6Al4V matrix composites was remarkably reduced by an order of magnitude compared with the conventional Ti6Al4V alloys at 550 oC, 600 oC, 650 oC under the stresses between 100 MPa and 350 MPa. Moreover, the rupture time of the composites increased by 20 times, compared with Ti6Al4V alloys at 550 oC/300 MPa. The superior creep resistance can be attributed to the two-level hierarchical microstructures and the two-scale reinforcements. The micro-TiBw reinforcement in the first network boundary contributed to creep resistance primarily by blocking grain boundary sliding, while the nano-Ti5Si3 particles in the second network boundary mainly by hindering phase boundary sliding. In addition, the nano-Ti5Si3 particles were dissolved to smaller-sized Ti5Si3 particles during creep deformation due to high temperature and external stress, which can further continually enhance the creep resistance. Finally, the creep rate during steady-state stage was unprecedentedly decreased, not stable or increased, which manifested superior creep resistance of the composites. The calculated results indicated that the dislocation climb is the dominant mechanism for the composites tested at 550 oC/(250-350) MPa and 650 o C/(100-250) MPa.
Dissolution Behavior of a Titanium Nitride Sponge in Titanium Alloy Melt
Authors: Mizukami Hideo , Kitaura Tomoyuki , Shirai Yoshihisa
Published: October 2020

The dissolution behaviors of titanium nitride titanium sponges in titanium alloy melt were examined. A titanium nitride sponge was produced using nitrogen gas. The titanium nitride sponge featured a porous structure. Porous structures at both the surface layer and inside were formed at intervals of about 5.0 × 10-5 m. When the titanium nitride sponge was immersed into a titanium alloy melt, the melt permeated into the pores. The dissolution rate of the titanium nitride sponge in the titanium alloy melt depends on the temperature of the melt. Higher melt temperatures corresponded to higher dissolution rates. However, the concentration of nitrogen in the titanium nitride sponge had no influence on the dissolution rate. Dissolution model of the titanium nitride sponge into the titanium alloy melt were proposed. These models considered the structure of the sponge; thus, the behavior of the dissolution sponges was predicted and confirmed.
Forecast of the fatigue crack initiation site of commercially pure Titanium miniature specimens with local surface topography data
Authors: Böhme L. , Ströer F. , Keksel A. , Seewig J. , Kerscher E.
Published: October 2020

Surfaces of technical components rarely appear in perfectly smooth condition. During fatigue loading, stress concentrations at surface asperities cause localized plastic deformation that can lead to crack initiation. Therefore, we have established a computer-aided method based on material ratio curves to investigate the possibility to predict the crack initiation site in fatigue tests by using detailed information on the local surface topography.

The present study shows the results of investigations on the mutual influence of the average grain size and the surface condition on the fatigue behavior of commercially pure Titanium (cp-Ti) miniature specimens. Three cp-Ti states were investigated: two types of coarse-grained cp-Ti Grade 2 with 35 µm and with 100 µm average grain size and one ultrafine-grained cp-Ti Grade 4 state with less than 2.5 µm average grain size. Confocal microscopy provided the surface topography data of all specimens and data post-processing was applied to the topography in order to locate critical areas where crack initiation may preferentially occur. These areas were compared with the actual crack initiation areas in fatigue test. Finally, scanning electron microscopy (SEM) images of the fracture surfaces were studied to analyze fatigue crack initiation site and crack path of the three microstructural states.
Change of microstructure and properties of dual titanium alloy join interface in hot working history
Authors: Zekun YAO , Yongquan NING , Zhanglong ZHAO , Darong HUANG , Hongzhen GUO
Published: October 2020

In order to get workpiece with high tensile stresses in bore region and high temperature duration, creep strength in outskirts, the dual alloy samples made of high temperature titanium alloy Ti60 and high strength titanium alloy Ti6246 had been joined by inertia friction welding(IFW). Then these samples were isothermal forged at 9400c and 9750c, and different heat treatment followed. Changes of microstructure and properties of dual titanium alloy join interface in hot working history were examined at this article. The results show equiaxed α structure varied into basketweave structureat at as-welded join interface, especially a character of widmannstaten structure emerged from Ti6246 alloy side heat effect region, after gradient heat treatment. Immersed ultrasonic testing prove deformation can availably eliminate weld defect through metal on two side of weld line deeper embedding each other. The results of properties test also show the join strength of dual titanium alloy through isothermal deformation and gradient heat treatment are better than that of as-welded samples. Tensile strength, yield strength, elongating rate, reduction in area of sample at 5500c also increase 51 to145 MPa, 37 to 101 MPa, 1.6% to 5.3%, 15.3% to 3.3% than that of as-welded samples respectively. The rupture life of Ti60/Ti6246 dual titanium samples with join interface can sustain to go beyond 100 hours at 5500c and 320 PMa stress.
Mechanical properties and deformation mechanisms in microscale Ti-55531 alloy
Authors: Kou Wenjuan , Sun Qiaoyan , Xiao Lin , Sun Jun
Published: October 2020

The mechanical behaviors and deformation mechanisms of solution treated and 450°C aged Ti-55531 alloy microsamples are investigated by the micro-compression and micro-bending. The results show that the dislocation slip is a concentrated movement in the solution treated microsamples which containing nanoscale ω phase. Under the tensile and compressive stress, there were serious strain bursts occurred in the plastic deformation of solution treated microsamples. But the dislocation slip is transmit at the phase interface in the 450°C aged microsamples which containing high density of α phase. The deformation behavior exhibits high strength and excellent stability in the micro-compression and micro-bending process. The different mechanical behaviors and deformation mechanisms of Ti-55531 alloy containing different second phase have significant guidance for tailoring the microstructure and mechanical properties.

Key words: Titanium, Micro-compression, Micro-bending, Dislocation, Mechanical behavior
Study on Microstructure and Mechanical Properties of Low Cost Ti-Fe-B Alloy
Authors: Sun Yangyang , Chang Hui , Fang Zhigang , Dong Yuecheng , Dan Zhenhua , Guo Yanhua , Zhou Lian
Published: October 2020

Microstructure evolution and mechanical properties of low cost Ti-2Fe-0.1B alloy under different heat treatment were studied. Results indicated that two kinds of equiaxed microstructures with different characteristics were obtained in conventional and double annealing, and typical lamellar microstructure was obtained in β annealing. Tensile test results shown that as-received rolled alloy possess highest strength and plasticity simultaneously due to fine and entangled microstructure. Uniform equiaxed dimples were observed in microstructure, which revealed ductile fracture morphology.

Key words: titanium alloy; microstructure; heat treatment; mechanical properties
Effect of morphology of primary a on fatigue crack propagation resistance in a near a heat resistant Titanium alloy
Authors: Sumi Y. , Takabayashi H. , Li Hangyue Y. , Bowen P.
Published: October 2020

DAT54 is a new near a heat resistant Ti alloy developed for disk applications in the compressor part of jet engines. DTA54 with bimodal microstructure shows a good balance of fatigue strength and creep life, and performs better than Ti-6242s up to 873 K. However, the influence of microstructure on properties, especially the effect of the morphology of primary a on fatigue crack growth resistance is not understood. In this study, samples with different types of microstructure were prepared by applying different heat treatment temperatures, and the influence of microstructure on fatigue crack growth properties at ambient temperature and 823 K was investigated. Influence of environment was also investigated by testing in vacuum and in air condition. Acicular microstructure shows lower fatigue crack growth rates in Paris’ region than the bimodal microstructures at 823 K. For the bimodal structures, aspect ratio of primary a do not have apparent influence on fatigue crack growth rates in Paris’ region, whereas fatigue threshold (DKth) seems to be affected by the morphology of primary a.