Advances in Titanium Technology: On-Demand Oral Presentations
Sponsored by: TMS Structural Materials Division, TMS: Titanium Committee
Program Organizers: Yufeng Zheng, University of North Texas; Zachary Kloenne, Ohio State University; Fan Sun, Cnrs Umr 8247 - Chimie Paristech Psl; Stoichko Antonov, National Energy Technology Laboratory; Rongpei Shi, Harbin Institute of Technology
Monday 8:00 AM
March 14, 2022
Room: Materials Design
Location: On-Demand Room
Towards Sub-nanometer Scale Characterizing the ‘Real’ H in Titanium Alloy - Importance of Combined Cryogenic Focused Ion Beam & Atom Probe Tomography Technique: Yanhong Chang1; Wenjun Lu2; Abigail Ackerman3; David Dye3; Dirk Ponge2; Dierk Raabe2; Baptiste Gault2; 1Institute of Materials, China Academy of Engineering Physics; 2Max Planck Institute für Eisenforschung, Düsseldorf; 3Department of Materials, Royal School of Mines, Imperial College
Atom probe tomography (APT) enables to characterize and visualize the 3D distribution of H at sub-nanometer scale within engineering materials. For Ti-alloys, cryogenic focused-ion beam (cryo-FIB) is proved to efficiently inhibit the introduction of H from the environment during specimen preparation, meanwhile, prevent out-diffusion of preexisting H/D previously charged into the material. By using cryo-FIB for sample preparation and semi-correlative STEM-EELS/APT for structural/chemical characterization, the controversial face-centered-cubic phase in electro-polished thin foils of cold-rolled commercially pure Ti was unambiguously identified as Ti hydride, instead of a new allotrope of Ti. The influence of D pre-charging on the chemistry and phase composition of the commercial alloy Ti6246 was investigated by using combined cryo-FIB&APT techniques. The results imply that the experimental parameters, such as H fugacity, charging temperature, etc., need to be carefully selected when aiming to study the hydrogen embrittlement behavior of Ti-alloys in services.
New Strain-transformable Titanium Alloys Displaying Combined TRIP and TWIP Effects: From Design Approaches to Deformation Mechanisms: Régis Poulain1; Stéphanie Delannoy2; Ivan Guillot3; Fabienne Amann4; Raphaëlle Guillou5; Jean-Philippe Couzinié3; Lola Lilensten1; Stoichko Antonov6; Baptiste Gault7; Frédéric De Geuser8; Dominique Thiaudière9; Jean-Luc Béchade5; Emmanuel Clouet5; Frederic Prima1; 1Chimie ParisTech; 2Chimie ParisTech, Biotech Dental; 3Université Paris Est Créteil; 4Chimie-ParisTech, Université Paris Est Créteil; 5Université Paris-Saclay, CEA; 6Max-Planck-Institut für Eisenforschung ; 7Max-Planck-Institut für Eisenforschung; 8Université Grenoble Alpes; 9Synchrotron SOLEIL
Among the various significant questions affecting titanium metallurgy, the effect of interstitials, more specifically oxygen, on the (mechanical) properties of titanium alloys remains one of the most critical issues. For decades, oxygen has been considered as a detrimental element, leading to drastic embrittlement. However, there is still an important lack of knowledge on underlying mechanisms regarding this effect. This talk proposes a new insight on these facts, based on an extensive work performed on Ti-Zr-O alloys displaying high oxygen concentration (between 0.4 and 1wt%). Two different aspects of great interest are discussed: (1) the determination of the atomic scale structure of Ti-O alloys, as a function of the chemical composition, with special attention to possible local ordering or local oxygen-driven structural modification. (2) The impact of oxygen content on: (a) the macroscopical properties (resistance/ductility trade-off) and: (b) the operative deformation mechanisms, at room temperature.
Multiscale Modeling of Metal-hydrogen Interactions: A Case Study of Hydride Formation in Titanium: Tae Wook Heo1; Kyoung Eun Kweon1; Nathan Keilbart1; Rongpei Shi1; Ryan Mullen1; Brandon Wood1; 1Lawrence Livermore National Laboratory
Metal-hydrogen interactions are an important topic in physical metallurgy. The associated mechanisms involve the complicated coupling of chemical/physical processes over multiple length and time scales. This presentation will focus on our multiscale modeling effort for hydrogen-titanium interactions. Ti alloys are outstanding materials for aerospace and biomedical applications owing to their excellent strength to weight ratio and corrosion resistance. However, gradual pickup of hydrogen often forms hydrides, degrading mechanical properties. We will discuss how the associated multiphysics modeling factors are combined within the mesoscale modeling framework to describe hydride formation in a polycrystalline system. We will then present how materials parameters for polycrystalline Ti-H, which are derived from atomistic modeling approaches, are incorporated into the integrated framework. Particularly, we will show our systematic simulation study for analyzing the impacts of grain boundaries and surfaces on hydrogen diffusion kinetics, propensity for hydride formation, and hydride microstructure in concert with experimental characterizations.
Micromechanical Fracture Behavior of Distinct Interfaces in an Intermetallic TiAl Alloy: Michael Burtscher1; Markus Alfreider1; Klemens Schmuck1; Helmut Clemens1; Christoph Gammer2; Daniel Kiener1; 1Montanuniversitaet Leoben; 2Austrian Academy of Sciences
The applicability of modern TiAl alloys is limited by their low ductility and fracture behavior at ambient temperatures. This is governed by different interface strengths and the effect of alloying elements on the respective interfacial fracture properties. In this study, fracture toughness and J-integral of selected interfaces of a C and Si-doped TNM alloy are determined by notched micro cantilever experiments. Additionally, strains along these interfaces were measured using 4D-STEM microscopy. The crack propagation was analyzed by complementary continuous stiffness measurements and computer vision techniques. This allows to follow the current crack propagation through distinct lamellae or grains as well as along different interfaces during the in-situ fracture experiments. This enabled us to identify the influence of the crack path on the presence of interfacial strains due to misfit dislocations or segregated dopant elements. Furthermore, the effect of ζ-Ti5Si3 silicides on the fracture behavior for α2/γ interfaces was determined.
Beta Ti Alloys with Increased Oxygen Content and TRIP/TWIP Effect: Josef Strasky1; Dalibor Preisler1; 1Charles University
Alloys with TRIP of TWIP effect exhibit high ductility and very pronounced deformation strengthening, but their yield point is low. Increased concentration of oxygen causes interstitial strengthening in beta Ti alloys. The aim of the research is to develop an alloy with enhanced strength and TRIP/TWIP effect. Various Ti-Nb-Zr-O based compositions have been prepared by compaction and homogenization using SPS. Individual compositions have been studied by scanning electron microscopy and microhardness mapping. Compression tests were performed with simultaneous in-situ measurement of acoustic emission and digital image correlation (DIC). The deformed microstructures were analyzed by electron back-scatter diffraction (EBSD). Stress induced martensite and {332}<113> twinning was found in Ti-Nb based alloy with 0.5 wt% of oxygen and 7 wt% of Zr.
High-temperature Oxidation Behavior of Dilute Ti-Si Alloys at 800 °C: Thomas Valenza1; Emmanuelle Marquis1; 1University of Michigan
Pure titanium and titanium alloys possess high specific strength and good corrosion resistance, making them well suited to structural applications in various corrosive environments. However, their use is limited to approximately 550 °C because of rapid oxidation at higher temperatures. Although alloying with Si is known to significantly reduce oxidation rates, the mechanisms remain disputed and are likely influenced by nitrogen. We compared the oxidation kinetics of pure Ti and a dilute Ti-Si alloy at 800 °C and characterized the local microstructures and compositions of the scale and underlying metal. In Ar-O2, Si led to a dramatic reduction in scale thickness, partly associated with the formation of a continuous silicide layer between the scale and metal. In N2-O2, the alloy exhibited reduced oxygen dissolution in the metal, which may be associated with the combination of a compact scale and the presence of N in solid solution below the scale.
Grain Boundary Segregation and Its Implications Regarding the Formation of the Grain Boundary α Phase in the Metastable β-Titanium Ti–5Al–5Mo–5V–3Cr Alloy: Stoichko Antonov1; T.S. Prithiv1; Zachary Kloenne2; Rongpei Shi3; Yufeng Zheng4; Hamish Fraser2; Baptiste Gault1; 1Max-Planck-Institut für Eisenforschung GmbH; 2The Ohio State University; 3Lawrence Livermore National Laboratory; 4University of Nevada Reno
We investigated the origin of the deleterious grain boundary ⍺ phase formed during the aging of the β-titanium alloy, Ti–5Al–5Mo–5V–3Cr–0.5Fe (wt.%). We probed the composition of different grain boundaries from the as-quenched β condition and after heating and aging using correlative electron microscopy and atom probe tomography. Our analysis reveals strong segregation of some α-stabilizing elements along with a depletion of β-stabilizing elements. The thermodynamic calculations, based on the measured grain boundary compositions, indicate that the segregation significantly increases the chemical driving force for α nucleation upon aging. Subsequently, multiple α precipitates nucleate along the grain boundary during heating to the aging temperature, and conglomerate during the aging. This work provides essential insight into the formation of the undesired grain boundary ⍺ layers along prior-β grain boundaries in metastable β-Ti alloys and paves the way for microstructural engineering of these alloys with enhanced mechanical properties.
The Formation of Titanium Ultrafine Laminar Microstructures via Additive Manufacturing: Marco Simonelli1; Yau Yau Tse2; Pere Barriobero-Vila3; Richard Hague1; 1University of Nottingham; 2Loughborough University ; 3German Aerospace Center
The use of titanium alloys in Laser Powder Bed Fusion (L-PBF), one of the most prominent additive manufacturing techniques, has received considerable attention in recent years. In this study we present how the fast solidifications and cooling rates occurring during L-PBF present opportunities to manufacture Ti constitutions rich in β-eutectoid formers (e.g. Fe). In particular, we study the evolution of the microstructure of a novel Ti-6Al-4V-3Fe alloy during L-PBF with operando X-ray diffraction and a suite of microscopy techniques. The decomposition of the resulting metastable microstructure is then presented. Ad-hoc heat treatments are designed from high-temperature microstructural studies via high-temperature EBSD. Ultrafine α+β grain laminar microstructures result from pseudo-spinodal transformations triggered by early Fe partitioning. Such microstructures are associated to exceptional tensile strengths (>1100MPa) and good elongation (>13%). Findings support a new design strategy for advanced titanium alloys for use in L-PBF.
Fatigue Behavior of Additively Processed, PVD Coated Ti-6Al-7Nb Alloy for Biomedical Applications: Maxwell Hein1; Dominic Stangier2; David Kokalj2; Nelson Filipe Lopes Dias2; Hilke Oltmanns3; Kay-Peter Hoyer1; Jessica Meißner3; Wolfgang Tillmann2; Mirko Schaper1; 1Paderborn University; 2TU Dortmund University; 3University of Veterinary Medicine Hannover
Adapted mechanical properties, as well as biocompatibility, are required for materials used for biomedical applications, such as permanent implants. Among the (α+β)-titanium alloys, Ti-6Al-7Nb is a well-established biomaterial due to its high corrosion resistance along with its excellent biocompatibility and application-oriented mechanical properties. In additive manufacturing, laser powder bed fusion allows the production of patient-customized implants with complex geometries made from Ti-6Al-7Nb. To improve the tribo-mechanical properties and to further enhance the biocompatibility of printed Ti-6Al-7Nb, the deposition of physical vapor deposition (PVD) coatings is a highly effective approach. The influence of different biofunctional PVD coatings on the formation of biofilms as well as cell viability and proliferation is examined. Due to the permanent load exposure of the implants, the material behavior of uncoated and coated specimens for quasi-static, low- and high-cycle fatigue loading is investigated.
Mechanical Behavior of Ti-Ni-Fe Based B2 Pseudo Binary Intermetallic at Different Length Scales: Subha Panda1; Jayant Jain2; Sudhanshu Singh1; 1IIT Kanpur; 2IIT Delhi
Deformation in intermetallics is achieved by contrivances, such as using materials that deviate from stoichiometry and have metastable disordered structure, adding dopants such as boron or by phase transformations. And B2 structured intermetallics deform to different extent: polycrystalline NiAl (aluminides) elongates up to 1-2 % before fracture; ternary ZrCoNi elongate up to 18 %, respectively. Whilst binary B2 compounds have been explored a lot, only a few pseudo-binary B2 intermetallics have been investigated. This work focuses on Ti-based pseudo-binary intermetallic such as Ti-Ni-Fe. Microstructural and mechanical characterization have been carried out using SEM, XRD, EBSD, bulk compression, micro-indentation and nano-indentation. It is attributed that the variation in properties is not only due to the composition but also due to a cumulative effect of texture, stoichiometry leading to the presence of point defects, such as antisite, grain size and site preference energy due to effective ternary substitution.
Design and Characterization of New Metastable β Ti-Mo-Zr-Sn Alloys for Biomedical Applications: Manon Laurencon1; Damien Fabregue2; Akihiko Chiba3; Kenta Yamanaka3; 1INSA de Lyon; Tohoku University; 2INSA de Lyon; 3Tohoku University
Along with practical feedbacks during the past decades, some limits raised in the use of classical TA6V-ELI alloy for biomedical applications. In reaction, this work brings a contribution to the design and characterization of metastable â titanium alloys, with respect to biocompatibility. The potential of Ti-Mo based alloys for biomedical applications has been widely promoted. Thus, Ti-Mo-Zr-Sn quaternary alloys have been designed using the « d-electron method », with regard to corrosion resistance (Zr addition) and the embrittlement due to athermal-ω (avoided with Sn addition). The alloys were obtained by arc melting and were then subjected to thermomechanical treatments so that their microstructures were optimize. In addition, tensile tests were conducted in order to assess their mechanical properties according to their chemical compositions. Further research work consisted in investigating the deformation mechanisms using EBSD, in order to check the reliability of the « d-electron method » for the design of TWIP/TRIP metastable β titanium alloys
A Novel High-strength Beta Titanium Alloy Reinforced by Nanoscale Intermetallic Precipitates: Rosie Mellor1; Nicholas Jones1; Howard Stone1; 1University of Cambridge
Industrial applications of metastable beta titanium alloys have been steadily increasing due to their exceptional strength and high toughness. The vast majority of such alloys rely on alpha-phase strengthening, which requires multiple thermomechanical processing steps to achieve a suitable dispersion of precipitates. In this research, an alternative method of strengthening has been explored - the intragranular precipitation of an ordered intermetallic phase that exhibits a well-defined orientation relationship with the beta-matrix. Computational thermodynamics has been used to identify alloy compositions that may be fully solutioned at high temperatures before inducing precipitation at lower temperatures. In designing these alloys, attention has been focussed on more abundant elements to reduce cost and improve sustainability. These alloys exhibit an excellent strength-to-weight ratio. Funding is acknowledged from the EPSRC and Rolls-Royce plc.
Effect of Aging Treatment on Microstructure and Superelastic Properties of a High Zr-containing Ti–Zr–Nb–Sn Shape Memory Alloy: Shuanglei Li1; Yeon-Wook Kim2; Jung Gi Kim1; Tae-Hyun Nam1; 1Gyeongsang National University; 2Keimyung University
In this study, microstructure and superelastic properties of a Ti-40Zr-8Nb-2Sn (at.%) shape memory alloy were studied by transmission electron microscope and in-situ X-ray diffraction. Nanodomains and fine nano-scaled isothermal ω phases were formed in the alloy aged at 573 K for 1 h. The stress-induced β - α" martensitic transformation occurred in spite of the presence of nanodomains. The aged alloy exhibited excellent superelasticity with a large total recovery strain (7.1%), high ductility (11.6%) and high yield stress (578 Mpa), indicating that a good balance of functional and mechanical properties was achieved in the aged alloy when compared with other 573 K/1 h aged β-type Ti alloys showing low yield stress and/or poor ductility. The enhanced yield strength without significant loss of ductility in the aged Ti-40Zr-8Nb-2Sn is ascribed to the restriction of the isothermal ω growth due to the high Zr content and Sn addition.