Deformation Mechanisms, Microstructure Evolution, and Mechanical Properties of Nanoscale Materials: Deformation Mechanisms II
Sponsored by: TMS Materials Processing and Manufacturing Division, TMS: Nanomechanical Materials Behavior Committee
Program Organizers: Niaz Abdolrahim, University of Rochester; Matthew Daly, University of Illinois-Chicago; Hesam Askari, University Of Rochester; Eugen Rabkin, Technion; Jeff Wheeler, Femtotools Ag; Wendy Gu, Stanford University
Thursday 8:30 AM
March 23, 2023
Room: Aqua 300AB
Location: Hilton
Session Chair: Laurent Beland, Queen’s University; Penghui Cao, University of California, Irvine
8:30 AM
Multi Principal Element Borides from Amorphous Colloidal Nanoparticles: Melody Wang1; Mehrdad Kiani2; Brandon Lum1; Wendy Gu1; 1Stanford University; 2Yale University
Multi principal element (MPE) alloys, amorphous metals and ceramics can have high strength, toughness and hardness. Here, we present a colloidal synthesis route to MPE amorphous metal nanoparticles and their crystallized multi-metal boride counterparts. CoNiB and CoFeNiB amorphous metal nanoparticles of ~100 nm in diameter are fabricated. The elemental composition is characterized using TEM EDS, which shows a higher concentration of nickel at the outer surface and remaining metals within the core. The particles are crystallized via annealing in inert gas and characterized using XRD. These particles are then sintered under heat and pressure into millimeter-scale, nanocrystalline multi-metallic borides. Mechanical tests will be performed via nanoindentation and micropillar compressions to determine elastic modulus, hardness, yield strength and ductility. The mechanical properties of individual amorphous metal and crystalline boride nanoparticles are also determined using in-situ SEM compression tests. These properties are related to the core shell structure and nanoscale chemical heterogeneities.
8:50 AM
Mechanical Behaviour of Ni and Ni3Al Free-standing and Matrix-embedded Metallic Nanoparticles at Different Temperatures: Alla Ndiaye Dieng1; Celine Gerard1; Jonathan Cormier1; 1Institut Pprime - CNRS - ISAE-ENSMA
Nano-composite materials represent a tremendous opportunity for improving mechanical properties and/or multi-physics coupling. Nevertheless, the understanding of their deformation mechanisms is still limited, especially at lower scales. Few studies have already investigated the mechanical behavior of free-standing nanoparticles at room temperature. In the present work, we investigate both free-standing and matrix-embedded nanoparticle behavior thanks to molecular dynamics simulations. Uniaxial compressions are performed on 20nm-sized nanoparticles after relaxation/thermalization. The impact of the force field model is first studied in order to discuss the modelling representativeness of mechanical testing in molecular dynamics.The Ni3Al nanoparticle mechanical behavior is then investigated through a large spectrum of temperatures. The plastic deformation mechanisms are analyzed in details both for free-standing and Ni matrix-embedded nanoparticles. The effect of nanoparticle shape, crystallographic orientation or temperature on plasticity mechanisms and yield stress are discussed. Particular attention is paid to the interface and the effect of the misfit.
9:10 AM
An Experimental and Modeling Investigation of Creep Resistance of a Stable Nanocrystalline Alloy: C Kale1; R Koju2; B Hornbuckle3; K Darling3; Y Mishan2; Kiran Solanki1; 1Arizona State University; 2Geroge Mason University; 3ARL
Nanocrystalline (NC) materials possess excellent room temperature properties, such as high-strength, and toughness as compared to their coarse-grained counterparts. However, NC microstructures are unstable at higher temperatures. Significant grain growth is observed already at moderately low-temperatures, limiting broader applicability of NC-materials. Here, we present a design approach that leads to a significant improvement in the high temperature creep resistance (up to 0.64 of the melting temperature) of a NC Cu-Ta alloy. The design approach involves alloying of pure elements to create a distribution of nanometer sized solute clusters within the grains and along the grain boundaries. We demonstrate that the addition of Ta nanoclusters inhibits the migration of grain boundaries at high temperatures and reduces the dislocation motion. This leads to a highly unusual creep behavior. This design strategy can be readily scaled-up for bulk manufacturing of creep-resistant NC parts and transferred to other multicomponent systems such as Ni-based alloys.
9:30 AM Invited
Exploring Defect Behavior and Size Effects in Micron-scale Germanium from Cryogenic to Elevated Temperatures: Ming Chen1; Alla Sologubenko2; Jeffrey Wheeler1; 1ETH Zürich, Laboratory for Nanometallurgy, Department of Materials Science; 2ETH Zürich, Scientific Center for Optical and Electron Microscopy
Micron-sized single crystalline Germanium displays enhanced carrier mobility under mechanical straining, which makes it a key material for optoelectronics and ultrafast semiconductor devices. However, the extreme brittleness of Ge constrains its processing and applicability especially at low temperatures. In this study, we demonstrate Ge is plastically deformed even at cryogenic temperatures by using in situ compression of micropillars. Micromechanical tests were performed at temperatures from −100 to 400 °C (0.14 − 0.56 Tm). This wide temperature range includes two transitions in dislocation-mediated plasticity: shuffle-to-glide (~0.31 Tm) and brittle-to-ductile (~0.47 Tm). Dynamic mechanical tests were performed to measure activation parameters for each deformation mechanism. The size effect in defect-scarce Ge was observed to be weak for deformation via partial dislocations but more pronounced via perfect dislocations. This study provides in-depth information and comprehensive knowledge for the defect-mediated plasticity in tetravalent semiconductors and practical guidelines for fabrication of robust Ge-based micro-structures.
10:00 AM Break
10:20 AM
Hydrogen Effects on Mechanical Deformation, Dislocation Density, and Phase Separation in 4130 Steel: Zachary Buck1; Matthew Connolly1; May Martin1; Damian Lauria1; Jason Killgore1; Peter Bradley1; Yan Chen2; Ke An2; Andrew Slifka1; 1National Institute of Standards and Technology; 2Oak Ridge National Laboratory
Interrupted tensile tests were performed on AISI 4130 steel in air and under hydrogen pressures ranging from 260 psi to 2600 psi. Investigation by neutron diffraction of the deformed specimens reveal a hydrogen-dependent partitioning of ferrite and martensite phases as a function of applied strain. Dislocation densities of the two individual phases were extracted by analyzing the Bragg peak broadening using a Williamson-Hall approach. A phase transformation from predominantly martensitic steel to ferritic steel was also observed as a function of applied strain. Lastly, scanning Kelvin probe force microscopy (SKPFM) was used to measure hydrogen in 4130 steel. Results from SKPFM suggest a slower rate of hydrogen desorption from martensite grains compared to ferrite grains.
10:40 AM Invited
Numerical Recipes: Preparing Nanostructured Materials for Computational Studies, from Metals to Colloids: Laurent Karim Béland1; Hao Sun1; Peyman Saidi1; Yaoting Zhang1; Mark Daymond1; Isaac Tamblyn2; 1Queen's University; 2National Research Council, Canada
Numerical recipes: preparing nanostructured materials for computational studies, from metals to colloids.Analogously to physical experiments, the relevance of numerical simulations hinge on the quality of the samples at hand. In this presentation, numerical sample preparation methods will be discussed, exploring various nanostructured materials, including nanograined nickel, aluminium and bentonite clay. In the case of nickel, the mechanical properties of nanograined nickel prepared using different strategies will be compared and contrasted. In the case of aluminium, we will show how to use neural networks to predict how grains will reorient under deformation. In the case of bentonite clay, we will show how to upscale nano-scale interations to the mesoscale, and construct micron-scale models of bentonite clay, which mechanical properties are in good agreement with experiments.
11:10 AM
One-dimensional Migration of Prismatic Loop in Refractory High Entropy Alloy and Effects of Local Chemical Order: Hangman Chen1; Penghui Cao1; 1University of California, Irvine
One-dimensional migration of nanometer-sized prismatic loops in irradiated metals has been studied for decades to understand the fundamental mechanisms of structural materials degradation under extreme conditions. With high melting points, extraordinary mechanical strength and irradiation tolerance, body-centered cubic refractory high entropy alloys (HEAs) are promising materials for nuclear applications. However, the influence of high local chemical complexity on defect migration and evolution is not well understood. In this talk, we present the atomistic mechanisms and energy landscape underlying the one-dimensional migration of prismatic loops in refractory HEAs. Our results show that local chemical complexity increases the roughness of habit plane and impacts the migration behaviors. The effects of local chemical order on the one-dimensional migration will also be discussed.
11:30 AM
Role of Stacking Fault Energy in the Interaction of Extended Dislocations with Nanovoids: Ashley Roach1; Shuozhi Xu2; Darby Luscher3; Daniel Gianola1; Irene Beyerlein1; 1University of California, Santa Barbara; 2University of Oklahoma; 3Los Alamos National Lab
Voids are prolific in structural metals, ranging from nanometers to micrometers in diameter. On the nanoscale voids act as dislocation obstacles, increasing shearing stress and strengthening the metal. Phase Field Dislocation Dynamics (PFDD), an intermediate length-scale model, is rich in physics with discrete dislocations that evolve simultaneously with voids, while allowing for cell sizes relevant to part performance. Void strengthening and the influences of void size, void spacings, and material properties are investigated, with focus on stacking fault energy (SFE) for dislocations in fcc, which dissociate into Shockley partials. The critical stress for a dislocation to bypass a given void obstacle was tracked, which is related to bulk material yielding. In addition, dislocation bypassing behaviors and mechanisms were studied with climb and cross slip excluded. A linear trend between void fraction and obstacle strength was observed, bucking previously predicted trends from literature and any anticipated size effects at the nanoscale.
11:50 AM
Nanoindentation of Alumina and Multiphase Inclusions in 42CrMo4 Steel: Ruben Wagner1; Robert Lehnert1; Enrico Storti1; Lisa Ditscherlein1; Christina Schröder1; Steffen Dudczig1; Urs Peuker1; Olena Volkova1; Christos Aneziris1; Horst Biermann1; Anja Weidner1; 1TU Bergakademie Freiberg
Aiming to reduce nonmetallic inclusions in steels, a combined cleaning filter system was applied to 42CrMo4 steel causing formation of novel multiphase inclusions. These multiphase inclusions consist of TiO2-x and Al2O3 in a low-melting spessartine matrix and were characterized by nanoindentation, automated scanning electron microscopy (ASPEX), atomic force microscopy, focused ion beam technique and confocal laser scanning microscopy. Compared to pure Al2O3 inclusions, the spessartine multiphase inclusions are softer and have a lower Young’s modulus, fitting much better to the mechanical properties of the steel. The area below the indents was investigated by focused ion beam technique and transmission scanning electron microscopy revealing dislocations. Furthermore, the low-melting character of the spessartine matrix was proven by means of a confocal laser scanning microscope. Accordingly, the low-melting spessartine inclusions appear as liquid inclusions during steel melt processing and could contribute to clogging prevention in continuous steel casting.