Deformation Mechanisms, Microstructure Evolution, and Mechanical Properties of Nanoscale Materials: Mechanical Behaviors of Nanoporous and Nanoarchitectured Materials
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
Wednesday 2:00 PM
March 22, 2023
Room: Aqua 300AB
Location: Hilton
Session Chair: wendy Gu, Stanford University; Dan Mordehai, Technion
2:00 PM Invited
Second Phase Strengthening in Nanofoams and Nanolayers: David Bahr1; Alexandra Loaiza1; 1Purdue University
Materials with nm scale dimensions in planar (layers) and linear (ligaments in foams) form can exhibit high yield strength. We examined the solid solution and second phase particle strengthening to determine if a bulk strengthening mechanism would further increase the strength beyond size-induced strengthening using Zn and ZnO in Cu based nanofoams and Cu deposited in a non-equilibrium solution in a Nb/Cr multilayer thin film. In both cases the second phase (either through internal oxidation or precipitation) showed an order of magnitude increase in strengthening effect over the solid solution form. The precipitation hardened multilayer hardness increased from 6 to 10 GPa, while solid solution only showed a ≈500 MPa increase in strength. Similarly, the hardness of the foam increased by about a factor of two with the oxide particles, but showed no measurable increase in hardness between a Cu and Cu-10%Zn foam.
2:30 PM
Development and Characterization of Gradient Nanostructured Metals via Compositional Means: Alejandro Barrios1; James Nathaniel II1; Joseph Monti1; Khalid Hattar1; Douglas Medlin1; Remi Dingreville1; Brad Boyce1; 1Sandia National Laboratories
Nanocrystalline metals are usually highly unstable and exhibit poor ductility. Common strategies to overcome these two challenges are to introduce an alloying element, stabilizing the microstructure via kinetic and thermodynamic mechanisms, and to develop gradient nanostructured films. In this work, we combine both strategies and introduce a methodology to fabricate gradient nanostructured films via chemical compositional means. We demonstrate that annealing an alloyed PtAu thin film, fabricated with a compositional gradient, results in a film with a microstructural gradient. We employ phase-field modeling to further explore the competing mechanisms of Au diffusion and thermally induced grain growth. We additionally investigate the mechanical behavior of these gradient films and compare its behavior to microstructurally homogeneous films. This new fabrication method offers an alternative for the development of the next generation of thin films with increased mechanical performance. SNL is managed and operated by NTESS under DOE NNSA contract DE-NA0003525.
2:50 PM
Microstructure and Mechanical Deformation of Nanoscale Hydrogel Infusion-based Additively Manufactured Ni: Wenxin Zhang1; Julia Greer1; 1California Institute of Technology
Additive manufacturing of nano-sized metals is challenging because it requires high-precision nanofabrication capabilities and custom-synthesized precursors. We developed a nanoscale hydrogel infusion-based additive manufacturing (nanoHIAM) method to create 3D metallic structures with sub-micron dimensions, in which metal ions are infused into two-photon lithography-printed hydrogel matrices and subsequently thermally treated to form metal oxides then further reduced to parent metals. Using this technique, we fabricated nickel (Ni) nanopillars with ~200nm diameters and ~900nm heights. Transmission electron microscopy (TEM) reveals nanoHIAM-Ni to be nanocrystalline (d ~10nm). In-situ uniaxial pillar compressions unveiled yield strengths of ~2-3GPa, higher than the single-crystalline power-law and polycrystalline inverse/classical Hall-Petch predictions. We attribute this unique mechanical performance to the kinetically-driven microstructure, with nanovoids, nanotwins, and high boundary densities influencing the plasticity. Metal-nanoHIAM opens an experimental pathway for combining complex microstructures and geometries and fosters opportunities for nanoscale multifunctionality by introducing 3D architectures beyond 2D patterning.
3:10 PM
Silica-coated DNA Lattices as Mechanical Metamaterials: John Kulikowski1; Shuang Wang2; Melody Wang1; Yonggang Ke2; Wendy Gu1; 1Stanford University; 2Emory University
Lightweight and strong nanolattices show promise as impact resistance metamaterials. Typical lithographic fabrication methods face scalability issues. Additionally, as-printed structures typically have microscale features, and must be further processed (e.g. pyrolysis, coatings) to reach nanoscale dimensions. Self-assembled colloidal particle templates address scalability, but are generally limited to FCC structure. Here, we use self-assembled DNA to form octahedron lattices. These lattices are infiltrated with 1.8 nm thick silica, forming high strength core-shell lattice structures. Single crystal structures are on the order of ~5 µm, with ~40 nm unit cells. Structures are mechanically tested using in-situ SEM compression. Nanoscale size effects result in a yield strength of ~250 MPa and elastic modulus of ~850 MPa with density of ~0.5 g/cm3, which is comparable to state of the art lithographed structures. SEM imaging reveals two fracture regimes: cracking vertically and at 45o angles. FEA simulations are implemented to better understand this deformation behavior.
3:30 PM Break
3:50 PM Invited
Modelling the Mechanical Properties of Nanoporous Metallic Structures: Santhosh Mathesan1; Zhi Chen1; Ben Engelman1; Dan Mordehai1; 1Israel Institute of Technology
Nanoporous metals are attracting increasing interest to various emerging applications and in this talk I will present our recent studies on how both material properties and topological features of porous structures are related to mechanical properties. Using MD simulations of nanoporous Au nanopillars, we show that the stress-strain curves demonstrate an initial non-linear regime, followed by a stress plateau and a strong hardening stage. We developed a hybrid skeletonization/dislocation-analyses tool to discuss how the different features of the stress-strain curve depend on the ligament average diameter and the topology of the nanoporous structure. We extend the discussion to compression of spherical nanoporous Au nanoparticles, which can also be fabricated experimentally, and we emphasize on the importance of local densification. Finally, we go up the scales using finite elements simulations, to propose universal laws for the mechanical properties of porous lattice architectured structures in a large range of material properties.
4:20 PM
A Machine Learning Approach to Model the Mechanical Response of Nanofoams: Sepideh Kavousi1; Mohsen Asle Zaeem1; 1Colorado School of Mines
Nanofoam metals are low-density and impact-absorbing materials with various potential applications, such as shock absorbers. In this study, we developed a machine learning model to investigate how geometric attributes of closed cell aluminum nanofoams affect their mechanical response. The Voronoi tessellation method is used to make closed-cell nanofoam models with random pore sizes between 15 and 39 nm and wall thicknesses between 2.8 and 10 nm. All the training and testing data are generated by molecular dynamics simulations of uniaxial tensile and compression loading of the nanofoams. The machine learning model correlates the mean size of nanopores, their size distribution, and wall thickness to various mechanical properties such as elastic modulus, yield stress and strain, and strain after unloading.
4:40 PM
Micromechanics of Hybrid Ceramic-organic Nanoarchitected Materials: Diletta Giuntini1; 1Eindhoven University of Technology
The controlled assembly of matter at the nanoscale is leading to a broad spectrum of new functional materials with emergent collective properties. Oftentimes, however, self-assembled materials are affected by poor mechanical performance. A promising solution against this backdrop has been found in the tailored combination of multiple constituents into hierarchically structured hybrid materials. We present here the case of ceramic-organic nanocomposites featuring a periodic superlattice, i.e. supercrystallinity. Strategies for strengthening, stiffening, hardening and toughening these nanoarchitected materials are highlighted, together with the key role played by time-dependent deformation, via a combination of ex- and in-situ high resolution microscopy and synchrotron studies, supported by finite-element simulations.
5:00 PM
Size and Shape Effects on the Strength of Platinum Nanoparticles: Jonathan Zimmerman1; Anuj Bisht1; Yuri Mishin2; Eugen Rabkin1; 1Technion - Israel Institute of Technology; 2George Mason University
Mechanical properties of nanoparticles have received a great deal of attention due to growing interest in their applications. We have studied the compressive strength of Pt nanoparticles of widely varying shapes and sizes produced by the solid-state dewetting method and report a maximum compressive strength of 9.5 GPa. This strength approached the lower limit of the theoretical strength of bulk Pt, yet in relative terms it is lower than the strength of particle of other FCC metals - Au and Ni, fabricated using the same method. We report a clear size effect on strength – as reported in previous research – along with a novel shape effect. We formulated a combined power law describing the dependence of particles strength on their size and shape in terms of geometrical parameters which are easily accessible experimentally. Our experimental results are in a good agreement with previous computational studies on Pt strength.
5:20 PM
Observing and Quantifying Deformation Mechanisms in Metal Nanoparticles: Ruikang Ding1; Soodabeh Azadehranjbar1; Ingrid M. Padilla-Espinosa2; Andrew Baker1; Muztoba Rabbani2; Ashlie Martini2; Tevis D. B. Jacobs1; 1University of Pittsburgh; 2University of California, Merced
Small metal nanoparticles have important industrial applications due to their unique size-dependent properties, such as high reactivity and unique photoelectromagnetic properties. However, their performance and reliability depend on their mechanical integrity. Here we investigated the fundamental mechanisms governing deformation of platinum particles with single-digit-nanometer diameters. Specifically, we performed in situ compression testing inside of a transmission electron microscope. The loading force is measured with nanonewton-scale resolution. The nanoparticle’s shape, structure, size, and deformation are analyzed using real-time high–resolution video. The results reveal the competitive and cooperative interactions between defect-mediated and diffusion-mediated deformation mechanisms.