Phase Transformations and Microstructural Evolution: Non-Ferrous Alloys I
Sponsored by: TMS Materials Processing and Manufacturing Division, TMS: Phase Transformations Committee
Program Organizers: Ashley Paz y Puente, University of Cincinnati; Mark Aindow, University of Connecticut; Sriswaroop Dasari, Idaho National Laboratory; Ramasis Goswami, Naval Research Laboratory; Megumi Kawasaki, Oregon State University; Eric Lass, University of Tennessee-Knoxville; Joshua Mueller, Michigan Technological University; Eric Payton, University of Cincinnati; Le Zhou, Marquette University
Wednesday 8:30 AM
March 22, 2023
Room: 25C
Location: SDCC
Session Chair: Josh Mueller, Los Alamos National Laboratory
8:30 AM Invited
Application of the PRISMS-PF Framework to Recrystallization and Twin Evolution: David Montiel1; Yanjun Lyu1; Mohammadreza Yaghoobi1; John Allison1; Katsuyo Thornton1; 1University of Michigan
We demonstrate the capability of PRISMS-PF, a powerful open-source phase-field framework to simulate microstructure evolution. The competitive performance of this framework is enabled by the combination of a matrix-free finite element method with advanced adaptive meshing and parallelization strategies. We focus on two of the most recent efforts to integrate PRISMS-PF with other computational tools from the PRISMS Center at the University of Michigan in order to simulate microstructure evolution that requires a multi-scale description. The first one is the development of application to simulate the nucleation and growth of recrystallized grains during static recrystallization. The second is the development of an application to simulate the formation, propagation and growth of twins in Mg alloys. We also discuss the most recently added features to enhance PRISMS-PF performance, ease of use, and integration with other computational tools, such as the Materials Commons information repository and collaboration platform.
9:00 AM
Phase Transformations and Twin Microstructure in Titanium: Lei Cao1; Amir Hassan Zahiri1; Jamie Ombogo1; Eduardo Vitral1; Mehrab Lotfpour1; 1University of Nevada
For Ti and Zr, ω-phase is the high-pressure phase and bcc is the high-temperature phase. In this work, we perform molecular dynamics simulations to study the deformation process of ω-Ti at low temperature and bcc-Ti at high temperature. We observe extensive ω-hcp and bcc-hcp phase transformation and the formation of rich martensite microstructure. Moreover, for the first time, we demonstrate that four types of transformation twins can be formed through the ω-α phase transformation or bcc-hcp phase transformation. The calculations of deformation gradients and transformation strains reveal that different types of transformation twins are favored by the specific loading directions.
9:20 AM
Understanding The Influence of Interfaces on Grain Nucleation in Highly Textured Mg-(Zn, Ca) Alloys During Static Recrystallization: Rogine Gomez1; Aeriel Leonard1; 1The Ohio State University
Deformation twinning plays a significant role during deformation of magnesium alloys due to its limited number of independent slip systems. Extension twinning contributes most significantly to c-axis deformation. During mechanical loading, these twins can serve as stress concentrators that act as preferential nucleation sites for new, strain-free, recrystallized grains during annealing. In this study, the microstructural and texture evolution of Mg-(Zn,Ca) alloys was quantified using a combination of in-situ heating, EBSD, and electron microscopy. The objective is to understand the influence of recrystallization and grain growth on crystallographic texture development in these alloys. TEM was used to understand the dislocation structure near twin boundaries, near other microstructural interfaces, and inside of twins. It was determined that binary alloys develop a strong basal texture during wrought processing that weakens during recrystallization. It was also found that twin boundaries served as preferential nucleation sites during the initial stages of recrystallization.
9:40 AM
Deformation Induced Solute Clusters and Precipitates in Light Metallic Alloys: Suhas Eswarappa Prameela1; Taisuke Sasaki2; Peng Yi3; Michael Falk3; Timothy Weihs3; 1Massachusetts Institute of Technology; 2NIMS, Japan; 3Johns Hopkins University
Recent studies have shed new light onto the mechanisms that control deformation enabled precipitation in Aluminum and Magnesium Alloys. These studies show how defect structure, density, and distribution can be manipulated to obtain a high number density of nanoscale precipitates and fine solute clusters. However, many challenges remain with designing effective thermomechanical processing routes. These include overcoming the competition between recrystallization and precipitation, decoupling the role of dislocations and vacancies in aiding the nucleation, and performing correlative microscopy studies. On the modeling side, there are challenges associated with capturing deformation gradients across multiple length scales and linking them to phase transformation processes. In this talk we will describe links between theory and experiments covering deformation enabled precipitation in Magnesium alloys and we will contrast them with those reported for Aluminum alloys.
10:00 AM Break
10:20 AM Invited
High-pressure Phase Transformation in Zirconium: Role of Slip Dislocations and Twinning: Arul Kumar Mariyappan1; T Yu2; Y Wang2; R McCabe1; C Tome1; Laurent Capolungo1; 1Los Alamos National Laboratory; 2University of Chicago
Group-IV transition hexagonal-close-packed (HCP) α-phase Zr is widely used in nuclear and chemical industries. With an increase in pressure, the HCP α-phase transforms into a simple-hexagonal ω-phase. This ω-phase is significantly stiffer, more brittle, and more plastically anisotropic than the α-phase. Understanding the α-to-ω transformation is relevant for enhancing the applicability of transition metals. In this work, using X-ray synchrotron experiments, the role of slip-dislocations and twinning on the α-to-ω transformation is investigated. The high-pressure experiments reveal that pre-existing prismatic<a> dislocations and tensile-twins favor the transformation compared to pyramidal<c+a> dislocations and compression-twins. Further, neutron diffraction-based in-situ pressure-hold experiments are performed to understand the transformation kinetics. These experiments find that the transformation rate increases with the holding pressure. Detailed analysis of the experimental data in connection with the Avrami equation finds that the nucleation and migration rates of slip dislocations increase with the imposed pressure and thus accelerate the α-to-ω transformation.
10:50 AM
Eutectoid Ordering Morphologies in Fe-Pd and Shockley’s (Controversial?) L1’ Phase: Adrian Savovici1; William Soffa1; Jerrold Floro1; 1University of Virginia
In Fe-Pd, the microstructure resulting from eutectoid decomposition, A1 -> L10 + L12, has never been explored, despite the potential for exchange-coupled ferromagnetism. We show that thermal aging of Fe–61.8 at% Pd bulk alloys at 650C produces well-known L10 polytwins, where L12 now coexists as nm-scale lamellae by wetting both the dodecahedrally-conjugated (110) twin boundaries and the L10 anti-phase boundaries. While this is nominally consistent with prior predictions by phase field modelling, the phase evolution is non-trivial. If this alloy is instead aged at 525C, L12 disappears, and secondary basal-plane ordering produces the Shockley L1’ phase. Predictions regarding this phase have been debated over decades, and direct experimental evidence has been quite limited. Our investigations aim to understand the stability, microstructure and the nature of the phase transformation (first- vs. higher-order and the role of magnetic energy) to L1’. National Science Foundation support through grant DMR-1709914 is gratefully acknowledged.
11:10 AM
Micro-addition of Fe in Highly Alloyed Cu-Ti Alloys to Improve Both Formability and Strength: Baptiste Rouxel1; 1Ecole Polytechnique Fédérale de Lausanne EPFL
Cu-Be alloys provide excellent electrical and mechanical properties, but it is progressively forbidden because of their high toxicity. The alternative alloys Cu-Ti have high mechanical resistance but show relatively low formability. This study showed that micro-additions of Fe can allow keeping a high concentration of Ti in solid solution and suppress the classical “wave-like” early-stage precipitation. Instead, a new dispersion of nano precipitates was observed. This behavior allows doubling the ductility in the solution annealed temper, together with maintaining a high strength after aging from precipitation of metastable nano α-Cu4Ti. A Cu-6Ti-0.3Fe alloy had an elongation of 48% at the solution annealed state and, after aging, had a very high yield strength of 975 MPa. This study shows that Fe micro-additions, when combined with higher amounts of Ti (6 wt%), enable the production of Cu-based alloys combining high formability and strength, providing an excellent alternative to Cu-Be in mechanical applications.
11:30 AM Invited
Alpha-Omega Phase Transformations and Microstructural Evolution in Shocked HCP Metals: Benjamin Morrow1; David Jones1; Ellen Cerreta1; 1Los Alamos National Laboratory
During shock loading, hcp metals (e.g. zirconium and titanium) can experience a phase transformation from hcp alpha phase to hexagonal omega phase. Omega phase is often retained in the microstructure after unloading, and has a strong influence on subsequent mechanical properties. A systematic study of the microstructural evolution under various shock conditions will be presented. Soft-recovered shocked samples were characterized using electron backscatter diffraction (EBSD) to observe and quantify crystal orientations and microstructural features (including twinning, phase variants formed during deformation, and textures) to determine likely transformation pathways. The kinetics of the phase transformation is also of interest, and in-situ experiments at the Advanced Photon Source, and shear experiments at LANL provide insight to the evolution during transformation. The combination of high-rate, in-situ and post-mortem data allow us to probe the mechanism and kinetics of phase transformations.