Nanostructured Materials in Extreme Environments: Nanostructured Materials in Mechanical Extremes
Sponsored by: TMS Materials Processing and Manufacturing Division, TMS Structural Materials Division, TMS: Nanomechanical Materials Behavior Committee, TMS: Advanced Characterization, Testing, and Simulation Committee, TMS: Mechanical Behavior of Materials Committee, TMS: Nuclear Materials Committee
Program Organizers: Haiming Wen, Missouri University of Science and Technology; Nan Li, Los Alamos National Laboratory; Youxing Chen, University of North Carolina Charlotte; Yue Fan, University of Michigan; Niaz Abdolrahim, University of Rochester; Khalid Hattar, University of Tennessee Knoxville; Ruslan Valiev, UFA State Aviation Technical University; Zhaoping Lu, University of Science and Technology Beijing
Wednesday 8:30 AM
March 22, 2023
Room: Aqua 303
Location: Hilton
Session Chair: Niaz Abdolrahim, University of Rochester
8:30 AM Invited
Understanding the Superior Strength and Localized Plasticity in Nanotwinned Ni-Mo-W Alloys: Mo Rigen He1; Arunima Banerjee1; Kevin Hemker1; 1Johns Hopkins University
The focus on nanoscience has greatly advanced our ability to synthesize, characterize, and model nanomaterials with unprecedented physical and chemical properties that are derived from dimensional constraints. Nanotwinned Ni-Mo-W possess ultrahigh strengths exceeding 4 GPa, which stem from its unique microstructure, ultrafine nanotwins densely packed in textured columnar grains. These materials also manifest extreme strain localization upon plastic deformation, but the microscopic mechanisms that lead to the activation and evolution of shear bands remain to be clarified. In this study, two materials with atomic composition of Ni84Mo11W5 and Ni86Mo3W11 are tested with nanoindentation and in situ SEM and TEM pillar compression. Combined with postmortem TEM imaging and orientation mapping, it is revealed that detwinning, spatially adjacent to and temporally prior to the developed shear bands, triggers the formation of shear bands. The potential role of alloy composition in facilitating early-stage plasticity and mitigating strain localization is further studied.
8:55 AM Invited
Phase Stability and Nanomechanical Behavior of Laser Direct Metal Deposited Concentrated Fe-Cu Alloys: Amit Misra1; 1University of Michigan
Non-equilibrium solute partitioning in laser additive manufactured concentrated binary alloys is shown to produce hierarchical multi-phase microstructures with feature sizes ranging from nanometer to micrometer length scales. Experimental and modeling results from concentrated Fe-Cu binary alloys, with 25-50 atomic% Cu, fabricated using laser direct metal deposition are analyzed. Cu phase exhibited nanoscale, coherent, metastable FCC Fe precipitates, while the Fe phase either had both nanoscale, coherent, metastable BCC Cu and semi-coherent FCC Cu precipitates or just the latter, depending on composition and processing history. The hierarchy of nanoscale precipitation is shown to produce synergistic mechanisms that simultaneously enhance flow strength and strain hardening. Phase stability of the nanoscale precipitates was evaluated using high-pressure diamond anvil cell experiments that revealed nanoscale phase transitions in both Cu and Fe precipitates.
9:20 AM Invited
Enhanced Thermomechanical Stability of Nanolamellar Composites Containing Thick 3-dimensional Interfaces: Nathan Mara1; Justin Cheng1; Zezhou Li2; Shuozhi Xu3; Youxing Chen4; Mauricio De Leo1; Jonathan Poplawsky5; Nan Li6; Jon Baldwin6; Irene Beyerlein3; 1University of Minnesota; 2Beijing Institute of Technology; 3University of California, Santa Barbara; 4University of North Carolina, Charlotte; 5Oak Ridge National Laboratory; 6Los Alamos National Laboratory
2-dimensional (2-D) interfaces with distinct boundaries demarcating an abrupt discontinuity in material properties in nanolayered composites are responsible for enhanced behaviors such as strength, radiation damage tolerance, and deformability. However, 2-D interfaces have limitations with respect to deformability and toughness. 3-D interfaces are defined as heterophase interfaces that extend out-of-plane into the two crystals on either side and are chemically, crystallographically, and/or topologically divergent, in three dimensions, from both crystals they join. We focus on thermal stability (up to 500° C) and mechanical behavior of nanolayered Cu/Nb containing interfaces with 3-D character. The resulting compositional gradient gives rise to new interphase boundary structures analyzed and quantified via S/TEM and Atom Probe Tomography. Micropillar compression results show the strength of nanocomposites containing 3-D interfaces is significantly greater than those containing 2-D interfaces. We describe structural evolution mechanistically through the use of atomistic and Phase Field Dislocation Dynamics simulations.
9:45 AM
Influence of Hydrostatic Pressure on Impurity Segregation in Nanocrystalline Metals: Zuoyong Zhang1; Chuang Deng1; 1University of Manitoba
Previous work evidenced that hydrostatic pressure would stabilize the ultrafine-grained metals and induce the elimination of inverse Hall-Petch effect. Herein, we employ molecular dynamics simulations to investigate the hydrostatic pressure effects on the impurity segregation in nanocrystalline metals. The results show that it will facilitate the segregation of Mg in nanocrystalline aluminum by increasing the pressure up to a critical value 5 GPa. Then, the preferred segregation grain boundary sites will be reduced under higher pressure. The existence of a maximum solubility in grain boundaries due to hydrostatic pressure in the Al-Mg system is unexpected and somewhat surprising. The underlying mechanisms are analyzed based on the influence of pressure on the local environments at grain boundary sites. It reveals that the free energy for impurity segregation is not a simple function of free volume at grain boundaries, which shed new light on alloy design for high pressure applications.
10:05 AM Break
10:25 AM Invited
Nanoscale Templating of Reinforcing Phases with Linear Complexions to Achieve Extreme Strength: Divya Singh1; Edward Li1; Hannah Howard2; Daniel Gianola2; Timothy Rupert1; 1University of California, Irvine; 2University of California, Santa Barbara
The stress fields around dislocations can induce local phase transformations, coined linear complexions. In this talk, we explore how linear complexions can directly modify dislocation motion, with an eye toward enabling pronounced strengthening and strain hardening in face-centered cubic alloys. Atomistic simulations are first used to uncover unique behavior for different types of linear complexions, including dislocation breakaway, faceting, and nucleation from the complexion environment. The critical stress barriers are then identified for complexions with different sizes and spatial configurations, in order to build continuum descriptions of plasticity. Next, processing experiments are used to induce linear complexion formation and study their structure, demonstrating that a high density of strong obstacles can be achieved through this concept. Finally, mechanical deformation experiments in transmission imaging modes show that individual dislocation motion can be directly modified with linear complexions. As a whole, linear complexions provide a direct pathway for microstructure design of alloys.
10:50 AM Invited
Anomalous Mechanical Behavior of Nanocrystalline Binary Alloys under Extreme Conditions: S srinivasan1; B Hornbuckle2; S Turnage2; K Darling2; Kiran Solanki1; 1Arizona State University; 2ARL
Microstructural instability in traditional nanocrystalline-metals limits the understanding of the fundamental effect of grain size on mechanical behavior under extreme environments. In this work, the interplay between Ta concentrations and processing temperature on the resulting microstructure of a powder processed, fully dense Cu-Ta alloy along with their tensile and compressive behavior at different strain rates are investigated to probe the possibility of manipulating or tuning microstructurally dependent parameters to control the flow-stress upturn phenomenon. Consequently, the results reveal that there is a crucial length-scale, i.e., small grain size and appropriate cluster spacing, below which such upturn is damped out. The observation of changes in flow stress upturn behavior is consistent with the observed changes in measured high-rate plasticity, which enhances below the critical length scale. Overall, this work presents a systematic approach to control or engineer reduced high strain rate flow stress upturn behavior in metallic alloys, for high-rate applications.
11:15 AM
Micromechanics of Strain Localisation and Damage in a Spinodal Bronze: Felicity Worsnop1; C. Cemal Tasan1; 1Massachusetts Institute of Technology
Surface degradation through wear is a significant cause of early failure for bearings in aerospace and industrial applications. However, wear at sliding contacts involves highly localised and fluctuating stresses, generating complex micromechanical conditions. Microstructural complexity further complicates the understanding of these processes. For example, spinodally hardened bronzes have a hierarchical microstructure including nanoscale spinodal domains and ordered precipitate phases, which contribute significantly to its wear resistance. Here, we report in situ scanning electron microscopy scratch tests and tension tests, carried out to probe the micromechanical strain localisation and damage of a spinodal bronze, and to systematically evaluate the role of microstructural constituents.
11:35 AM
Nanotwin Stability under Temperature-dependent Deformation States: Jarod Robinson1; Akarsh Verma2; Eric Homer2; Gregory Thompson1; 1The University of Alabama; 2Brigham Young University
Nanotwins can provide significant strengthening; however, these same boundaries can also de-twin facilitating a loss of strength. This de-twinning behavior can become more prevalent at cryogenic temperatures. In this work, a series of copper nanotwinned columnar grains have been alloyed with aluminum. These alloys have been subjected to deformation at approximately -190°C and ambient temperature. Under indentation, at a lower aluminum solute content (2at.%), the columnar grains bent and corresponded with a loss of twins. In contrast, at a higher aluminum solute content (8at.%) the grains sheared and retained the high density of twins. Molecular dynamics based atomistic simulations reveal an increase in the incoherent twin boundary velocity with decreasing temperature (Non-Arrhenius behavior), but this boundary velocity is reduced and becomes more invariant with temperature as the solute content increases. Coupling increases in solid solution strengthening and nanotwin stabilization is used to explain the microstructural differences between the alloys.