Defect and Phase Transformation Pathway Engineering for Desired Microstructures: Simulation and Modeling
Sponsored by: TMS Materials Processing and Manufacturing Division, TMS: Phase Transformations Committee
Program Organizers: Yufeng Zheng, University of North Texas; Rongpei Shi, Harbin Institute of Technology; Yipeng Gao, Jilin University; Timofey Frolov, Lawrence Livermore National Laboratory; Stoichko Antonov, National Energy Technology Laboratory; Jessica Krogstad, University of Illinois at Urbana-Champaign; Bin Li, University Of Nevada, Reno
Tuesday 2:00 PM
March 16, 2021
Room: RM 55
Location: TMS2021 Virtual
Session Chair: Yipeng Gao, Idaho National Laboratory
2:00 PM
Interactions between Lattice Dislocations and 3D Metallic Interfaces: Shuozhi Xu1; Justin Cheng2; Nathan Mara2; Irene Beyerlein1; 1University of California, Santa Barbara; 2University of Minnesota, Twin Cities
In metallic systems, 3D interfaces are heterophase interfaces that extend out of plane into the two crystals. Unlike 2D sharp interfaces across which the material properties change abruptly, the 3D interfaces provide a smoother intergranular transition in material properties. In addition, a 3D interface itself is chemically and crystallographically dissimilar from the two crystals that join. While many numerical studies of the interactions between dislocations and 2D interfaces have been conducted, much fewer efforts were devoted to 3D interfaces in the same context. Here, we focus on the nanolayered Cu/Nb containing interfaces with 3D character. The interactions between dislocations and 3D interfaces are simulated via a phase-field dislocation dynamics (PFDD) method informed by atomic-level calculations. In PFDD, the heterogeneities with a general geometry and plastic deformation on general slip planes progress hand in hand. Selected simulation results are benchmarked against atomistic simulations and analytical solutions.
2:20 PM
Interfacial Segregation and Segregation-induced Transitions in a Polycrystalline Grain Boundary Network: Pulkit Garg1; Zhiliang Pang2; Vladyslav Turlo3; Timothy Rupert4; 1Arizona State University; 2Guilin University of Electronic Technology; 3Swiss Federal Laboratories for Materials Science and Technology (Empa); 4University of California, Irvine
Interfacial segregation can stabilize grain structures and even lead to interfacial complexion transitions. Atomistic simulations offer the highest resolution for characterizing grain boundary segregation, but most segregation studies are limited to bicrystal geometries. In this talk, we investigate the correlations between physical and chemical character of grain boundaries and subsequent structural transitions in polycrystalline Cu-rich alloys using hybrid atomistic Monte Carlo/molecular dynamics simulations. Physical parameters like excess free volume and atomic energy correlate strongly with solute content at grain boundaries in nanocrystalline Cu-Zr at a moderate temperature of 900 K, where segregation occurs but no complexion transitions are obvious. At a higher temperature state of 1050 K, a significant number of boundaries (~45%) are observed to transition to amorphous complexions with varying thickness. Overall, this work highlights that interfacial segregation is much more complex in a polycrystalline network than in a bicrystal system, with large variations in interfacial behavior observed.
2:40 PM
Twin Boundaries Continue to Surprise Us: Understanding Type II Twin in NiTi and {1012} Twin in HCP Materials: Ahmedsameerkhan Mohammed1; Huseyin Sehitoglu1; 1University of Illinois Urbana-Champaign
Twin Boundaries (TBs) are possibly the simplest interfaces that have an authoritative say in both structural and functional material behavior. Despite entertaining research for nearly a century now, they continue to surprise us with exciting behavior exemplifying the richness of material phenomena. This study investigates two TBs: the Type II TB in martensitic NiTi and the {1012} TB in HCP Ti. The Type II TB is possibly the only interface to date whose experimental characterization by multiple researchers has yielded disagreeing Miller Indices. This study recasts seemingly contrasting experimental evidence as consistent evidence of an evolving capability, allowing the interface to exhibit different indicial identities. Similarly, the {1012} TB has been under debate due to its unclear atomic structure and detwinning mechanism, both crucial in deformation of light HCP metals. This study uses modern atomistic simulation tools to systematically deduce an orderly shear-shuffle mechanism which reconciles earlier propositions.
3:00 PM
New Insights into The Effect of Solutes on Twinning in Ti Alloys: Shahriar Hooshmand1; Yan Chong1; Ruopeng Zhang1; Andrew Minor1; Mark Asta1; 1University of California, Berkeley
Ti alloys attract wide attention due to the unique combination of low density, high strength and corrosion resistance. Twinning is one of the essential plastic deformation mechanisms in Ti and other HCP materials, which impacts the mechanical properties. In this work, we systematically study various common twin modes activated under c-axis tension and compression using atomistic simulations. In agreement with our recent experiments, we find that addition of solutes to the elemental alpha-Ti can alternate the deformation twinning behavior and promote new twin modes. Density functional theory and molecular dynamics simulations are employed to investigate the mechanisms underlying the anomalous behavior of certain twins in presence of solutes. We also provide a comprehensive and quantitative analysis of thermodynamic and kinetic feasibility of solute transport around various twin boundaries. These insights can shed light on further understanding of complicated twinning behavior in Ti alloys and suggest novel strategies for materials design.
3:20 PM
Evolving Core Structures in Dislocation-twin Boundary Interactions: Orcun Koray Celebi1; Ahmed Sameer Khan Mohammed1; Francisco Andrade Chávez1; Jessica Krogstad1; Huseyin Sehitoglu1; 1University of Illinois Urbana Champaign
The superior performance of nanotwinned microstructures is fundamentally attributable to the dislocation-Twin Boundary (TB) interactions. However, this interaction exhibits a complex dependence on microstructural parameters such as twin crystallography and load orientation. Consequently, current state-of-the-art models follow a case-by-case analysis of each possible interaction, requiring expensive atomistic or dislocation-dynamics simulations. Furthermore, the existing models are not truly predictive in that they employ some form of empiricism. We develop a predictive analytical framework devoid of empiricism, extending the idea of a Generalized Peierls-Nabarro model. Analytical predictions are validated against atomistic simulations employing Molecular Dynamics (MD). We propose for the first time, the non-planar core structures of sessile dislocations of the reactions. We uncover the sensitivity of twin interaction stresses on planar fault energies, aimed to inform exploration of the compositional design space for superior nanotwinned alloys.
3:40 PM
Characterizing and Modeling Collective Atomic Displacements during Grain Boundary Migration: Ian Chesser1; Anqi Qiu1; Ankit Gupta2; Garritt Tucker2; Brandon Runnels3; Elizabeth Holm1; 1Carnegie Mellon University; 2Colorado School of Mines; 3University of Colorado Colorado Springs
In this work, we leverage high-throughput molecular dynamics simulations and a forward model for atomic displacements in the dichromatic pattern to characterize migration of a crystallographically diverse set of grain boundaries (GBs). We introduce the displacement texture construction, inspired by spin textures and dynamic structure factor, to quantify transition paths during GB motion. Displacement textures reveal a variety of interesting symmetry-breaking phenomena characteristic of high temperature shuffling. An optimal transport based forward model allows separation of ordered shuffles in the dichromatic pattern from diffusive, string-like displacements. Our analysis extends to shear coupling scenarios in both bicrystals and polycrystals. It is found that vortex displacement patterns frequently correspond to multimodal disconnection motion under constraints. Metastable states play an important role in determining boundary plane anisotropy of collective displacement patterns. Although our characterization supports existing models for grain boundary migration in some cases, many examples call for more flexible models.
4:00 PM
Assessment and Design of Complex Microstructural Features in Zirconia Shape Memory Ceramics via Elasto-Plastic Phase-field Modeling: Cheikh Cissé1; Mohsen Asle Zaeem1; 1Colorado School of Mines
Shape memory ceramics have large transformation temperature windows in the range 0-500 oC, which is appealing for various engineering applications. However, the lack of comprehensive understating of their microstructure-controlled thermomechanical response have hindered their further developments and applications. In this work, we present the most complete and fully thermomechanically coupled phase-field model to quantitively predict the microstructure-controlled pseudoelasticity and shape memory responses of stabilized zirconia. The model has been used to analyze the reversible monoclinic-to-tetragonal phase transition in zirconia-based shape memory ceramics. This model considers the suppressive effects of grain boundaries on the phase transformation, the pernicious effects of plastic deformation on the shape recovery, the effects of grain orientations on the degree of transformation, the effects of microvoids on the mechanical response, and the interaction of microcracks with the phase transformation during reversible transformation. The proposed model can guide designing the microstructures of shape memory ceramics.
4:20 PM
Pseudoelastic Response of Ion-implanted Nickel-titanium Shape Memory Alloy: Combining Experimentation and Forward Modeling: Daniel Hong1; Harshad Paranjape2; Peter Anderson1; Alejandro Hinojos1; Michael Mills1; Khalid Hattar3; Nan Li4; Jeremy Schaffer5; 1The Ohio State University; 2Confluent Medical; 3CINT Sandia National Laboratories; 4CINT Los Alamos National Laboratories; 5Fort Wayne Metals
This work reports on an experimental-simulation approach to determine the effect of Ni-ion implantation on the pseudoelastic-plastic response of Ni-rich NiTi shape memory alloys. A key aim is to achieve a strain glass response by manipulating nucleation and pinning sites for phase transformation. Near-surface regions of ion-implanted material are investigated using nanoindentation and electron microscopy and coupled with finite element simulations of nanoindentation. The approach provides a means to quantify the effects of ion implantation on the stress-induced phase transformation and crystal plasticity in the austenite phase. Initial results show that ion-implantation can more than double hardness while increasing the percent of recoverable displacement during indentation. The results suggest the potential for ion-implantation to improve wear and fatigue resistance of Ni-Ti shape memory alloys.This work is supported by the Department of Energy, Basic Energy Sciences (DE-SC0001258), Center for Integrated Nanotechnologies (2019BC0126), and Ohio Supercomputing Center (PAS0676).
4:40 PM
Investigation of Nucleation Mechanisms Associated with Formation of Co-precipitates in Ni-based Superalloys: Hariharan Sriram1; Semanti Mukhopadhyay1; Rongpei Shi2; Michael Mills1; Yunzhi Wang1; 1The Ohio State University; 2Lawrence Livermore National Laboratory
Experimental studies have shown that IN 718-based alloys could form a rich variety of co-precipitate microstructures through careful control of alloy chemistry and heat treatment. Although the growth and coarsening mechanisms of the co-precipitates have been investigated, nucleation of γ" or γ' on existing γ' or γ" core is yet to be understood. In this presentation we will show a quantitative assessment on the effects of concentration and stress field associated with an existing and growing γ' or γ" precipitate on the nucleation of γ" or γ' precipitates, leading to the formation different co-precipitate configurations. The chemical driving force for nucleation are calculated using the CALPHAD approach and databases, while the contributions from the elastic interaction and interfacial energies between different interfaces are quantified by using a combination of a multi-phase field free energy formulation and a saddle point search algorithm, i.e., the nudged elastic band method