Advances in Titanium Technology: Deformation Behavior in Ti Alloys I
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
Tuesday 2:30 PM
March 1, 2022
Room: 252A
Location: Anaheim Convention Center
Session Chair: Fan Sun, PSL Research University
2:30 PM
Transformations in TRIP/TWIP Ti Alloys Studied via In-situ Methods: Fan Sun1; Bingnan Qian1; Lola Lilensten1; Philippe Vermaut1; Frédéric Prima1; 1PSL Research University
The presentation focuses on the in-situ studies of transformations in TRIP/TWIP Ti alloys including thermally induced omega precipitations. The deformation-induced transformations lead to complex microstructure due to simultaneous activation of various types of twinning and stress-induced martensite. Such active microstructural responses to strain/stress result in important improvements of strain-hardenability and ductility of the alloy. For a better understanding of the mechanisms, the deformation-induced twinning/martensite have to be studied via in-situ EBSD/TEM under mechanical loading because some transformations are reversible. Moreover, the strengthening of TRIP/TWIP Ti alloy via isothermal omega precipitation can be achieved by increasing the CRSSs of the deformation-induced twinning/martensite without suppressing them. Remarkable improvement on tensile strength (470 -> ~900MPa) is obtained without ductility (40%) trade-off on a simple Ti-12Mo. The omega precipitation is investigated by in-situ resistivity measurements and in-situ TEM under heating.
2:50 PM
In-situ Synchrotron X-ray Diffraction of High Strain Rate Deformation of TRIP/TWIP Ti-Mo Alloys: Benjamin Ellyson1; Kamel Fezzaa1; Tao Sun1; Niranjan Parab1; Christopher Finfrock1; Connor Rietema1; Douglas Smith1; John Copley1; Chloe Johnson1; Chandler Becker1; Jonah Klemm-Toole1; Cody Kirk1; Nesredin Kedir1; Jinling Gao1; Weinong Wayne Chen1; Rajarshi Banerjee1; Kester Clarke1; Amy Clarke1; 1; 1Colorado School of Mines
The development of metastable beta titanium (Ti) alloys promises to expand their use in plasticity and damage critical applications, where crash resistance, cold forming or blast resistance are needed. These conditions require intimate knowledge about the dynamic behavior of metastable beta-Ti alloys. Here we performed simultaneous ultrafast synchrotron x-ray diffraction and imaging during high strain tensile deformation to compare the microstructural evolution of a TRIP/TWIP Ti-12Mo (wt.%) alloy to a TWIP-only Ti-15Mo (wt.%) alloy. Both alloys exhibited microstructural evolution similar to that observed after quasi-static and intermediate strain rate testing. However, post-mortem microstructural characterization revealed the activation of TRIP after TWIP in the Ti-12Mo alloy led to finer microstructural refinement compared to TWIP alone in the Ti-15Mo alloy. Ultimately, the finer microstructure formed by TRIP in Ti-12Mo resulted in increased total elongation at strain rates up to 2000 s^-1.
3:10 PM
Characterization of Nanoscale Metastable Phases in a TRIP Titanium Alloy: Wenrui Zhao1; Dian Li1; Yufeng Zheng1; 1University of Nevada, Reno
Transformation-induced plasticity (TRIP) titanium alloys have been recently designed to achieve synergetic high strength and great ductility. In these TRIP titanium alloys, various nanoscale metastable phases have been characterized including hexagonal omega phase and orthorhombic O’ phase, which may play an important role in determining the mechanical performance of these alloys. In this work, nanoscale metastable phases in a TRIP Ti-23Nb-0.7Ta-2Zr-1.2O (at.%) alloy were studied using scanning electron microscopy, transmission electron microscopy, and aberration-corrected scanning electron microscopy. The structure of nanoscale omega phase and O’ phase particles were observed using atomic resolution high angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) imaging. Different atom shuffle mechanisms to form omega phase and O’ phase will be introduced. This work is funded by the Research Enhancement Grant from University of Nevada Reno.
3:30 PM
Assessing the Variability in Mechanical Properties of Biocompatible Ti-13Nb-13Zr Titanium Alloy with Respect to Thermomechanical Treatments and Associated Microstructures.: Stephanie Delannoy1; Sarah Baïz2; Pascal Laheurte3; Laurence Jordan4; Frédéric Prima5; 1PSL Research University, Chimie ParisTech - CNRS, Institut de Recherche de Chimie Paris UMR CNRS 8247 / Biotech Dental; 2Laboratoire Procédés et Ingénierie en Mécanique et Matériaux, PIMM, ENSAM, UMR 8006, CNRS, CNAM; 3Laboratoire d’Etude des Microstructures et de Mécanique des Matériaux, LEM3 UMR CNRS 7239, Université de Lorraine; 4PSL Research University, Chimie ParisTech—CNRS, Institut de Recherche de Chimie Paris UMR CNRS 8247 / Dental Faculty, Université de Paris / Hospital Rothschild, AP-HP; 5PSL Research University, Chimie ParisTech—CNRS, Institut de Recherche de Chimie Paris UMR CNRS 8247
Thanks to an advantageous combination of chemical, biological and mechanical properties, titanium and its alloys are extensively used for manufacturing dental implants. However, studies have shown that elastic mismatch observed at the bone-implant interface could result in either stress shielding or peak stresses and subsequent reduced osseointegration. To address this, numerous works have been initiated to minimize the elastic modulus, by developing new alloy grades, low-modulus coatings, or even porous structures. Nevertheless, since isoelasticity is essentially required on surface, the present work was based on a new and original approach aiming at creating elastically graded materials. In that context, a thorough study on Ti-13Nb-13Zr alloy has been performed with respect to thermomechanical processing. It appeared that this material could display a wide variety of microstructures accompanied by a large elastic variability, ranging from 50GPa to 80GPa, making this alloy suitable to produce graded implants.
3:50 PM Break
4:10 PM
Twins in Ti under Different Loading Conditions: Nilanjan Mitra1; 1Johns Hopkins University
The presentation highlights observance of different types of twinning along with it’s variant for various types of applied loading on Ti single crystals along different directions [numerous publication of author]. Overall, it was observed that activation of twin systems and its variants cannot be directly relegated to follow Schmid’s criterion irrespective of different loading conditions. It was also observed that under some loading conditions, twin variants with the same Schmid factor may not contribute equally to the total twin volume fraction. It should also be noted that even though twinning is one of the dominant plastic deformation mechanisms observed in Ti under different types of loading conditions, other mechanisms such as dislocation slips and phase transformations can also be observed in the material
4:30 PM
Formation of {11-22} Contraction Twins in Titanium through Reversible Martensitic Phase Transformation: Amir Hassan Zahiri1; Jamie Ombogo1; Lei Cao1; 1Universitiy of Nevada Reno
We report the discovery of a non-conventional {11-22} twinning mechanism in α-titanium through reversible α→ ω→ α martensitic phase transformations. Specifically, the parent α-phase first transforms into an intermediate ω-phase, which then quickly transforms into a twin α phase, leading to the formation of {11-22} contraction twins. In addition, we prove that the reversible α→ ω→ α phase transformations follow strict orientation relations between the parent α-, intermediate ω-, and twin α-phases. Finally, we demonstrate that our mechanism agrees with classical twinning theory in the shuffle, shear, and conjugate twinning plane. This study reveals the important role of the intermediate ω-phase in the twinning process, adding critical details to the existing mechanism of {11-22} twinning.
4:50 PM
Critical Comparison of Estimation of Critical Resolved Shear Stress from Slip Line Trace Analysis and Spherical Indentation Protocols and Bayesian Learning Techniques for Ti 6Al-2Sn-4Zr-2Mo and Ti 6Al-2Sn-4Zr-6Mo Alloys: Soumya Mohan1; Arunima Banerjee2; Andrew Castillo1; Natalia Millan Espitia1; Biswaranjan Dash3; Zhuowen Zhao4; Shanoob Balachandran5; Dipankar Banerjee6; Surya Kalidindi1; 1Georgia Institute of Technology; 2John Hopkins University; 3Garrett Advancing Motion; 4Michigan State University; 5Alloyed; 6Indian Institute of Science
Understanding plasticity of titanium alloys with bimodal microstructures is crucial due to their applications to aero-engine parts. Estimation of critical parameters, specifically Critical Resolved Shear Strength (CRSS), is needed to inform crystal plasticity models. The accuracy and reliability of two different experimental methods of measuring CRSS values for the primary- α phase are compared critically in Ti6242 and Ti6246 alloys. The two methods compared were the spherical indentation stress-strain protocols (paired with Bayesian learning techniques) and slip line trace analysis. The slip resistance or CRSS values for indentation protocols for Ti6242 are 221 ± 18 MPa, 342 ± 49 MPa, 748 ± 135 MPa and 1150±188 MPa; and for Ti6246 are 189±4MPa, 359±9MPa, 820±27MPa and 1087±26MPa for prism a ⃗, basal a ⃗, pyramidal a ⃗, pyramidal (c ⃗+ a ⃗) slip, respectively. Slip ratios from indentation agreed well with the range of ratios calculated from slip line trace analysis.
5:10 PM
Characterization and Slip of <a> Screw Dislocation in Pure hcp α Titanium from Atomistic Simulations: Ali Rida1; Satish Rao2; Jaafar El-Awady1; 1Johns Hopkins University; 2UES, Inc.
The plastic deformation of pure hcp α Ti is carried out by the glide of <a> screw dislocations on the{-1100} prismatic planes. In this work, we used Molecular statics and dynamics simulations to determine the core structure and critical stress for the motion of <a> screw dislocations on the prism plane in α-Ti at low temperatures using a recently developed MEAM-spline potential for Ti-Nb. From Molecular statics at 0K we found two core structures, one spread on the pyramidalI plane and the other one on the prismaticI plane. In agreement with first-principle calculations, the pyramidalI core is the ground state core and ΔE between the two cores is 18.8 mev/b. Finally, MD simulations show that the screw dislocations glide by a kink-pair mechanism on the prismatic plane and the calculated Peierls stress vs T for the prismatic core are in good agreement with experimental low-temperature yield data for prismatic slip.