Article
Chemistry, Physical
Konstantin Lamp, Niklas Kuechler, Juergen Horbach
Summary: This study presents molecular dynamics computer simulations of a polydisperse soft-sphere model under shear, showing the existence of transient amorphous solid states and brittle yielding below the critical temperature T-c.
JOURNAL OF CHEMICAL PHYSICS
(2022)
Article
Materials Science, Multidisciplinary
Z. Q. Chen, M. C. Li, J. S. Cao, F. C. Li, S. W. Guo, B. A. Sun, H. B. Ke, W. H. Wang
Summary: The plastic deformation mechanism of A/ANLs remains unclear, with the study finding that the amount and morphology of A/AIs play crucial roles in their plastic deformation process.
JOURNAL OF MATERIALS SCIENCE & TECHNOLOGY
(2022)
Article
Multidisciplinary Sciences
Hongyi Xiao, Ge Zhang, Entao Yang, Robert Ivancic, Sean Ridout, Robert Riggleman, Douglas J. Durian, Andrea J. Liu
Summary: This study introduces a new structuro-elastoplastic (StEP) model to tune the degree of strain localization in disordered solids, based on the stability of the disordered local structure represented by a machine learning-based descriptor called softness. The model exhibits semiquantitative agreement with experimental results for different disordered solids and provides a microscopic understanding of the interplay between structure, plasticity, and elasticity in strain localization.
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
(2023)
Article
Materials Science, Multidisciplinary
A. S. Aronin, O. I. Aksenov, D. V. Matveev, E. A. Pershina, G. E. Abrosimova
Summary: The formation of shear bands and their relationship with surface steps in an amorphous alloy under rolling were investigated using scanning, transmission electron, and atomic force microscopy. It was found that shear bands initiated from surface steps with a thickness of approximately 10 nm, which varied in different locations. Secondary shear bands were also observed, located at an angle of 70 degrees to the shear band coming out to the surface. The regions of shear bands exhibited light and dark contrast, indicating a change in the density of the amorphous phase along the shear band. The surface steps had a complex shape and were composed of elementary steps, with thickness corresponding to that of the shear band.
Article
Chemistry, Physical
Galina Abrosimova, Dmitry Gunderov, Evgenia Postnova, Alexandr Aronin
Summary: X-ray diffraction and scanning electron microscopy were used to study the structural changes in amorphous alloys under high-pressure torsion and multiple rolling. Shear bands were formed during deformation, which had lower density compared to the surrounding non-deformed amorphous matrix. Shear bands provided increased free volume, promoting crystallization processes. The proportion of free volume under different deformation types was estimated. The appearance of steps on the surface, the number of shear bands, and the surface morphology of deformed amorphous alloys were influenced by deformation type and material properties. The findings were discussed in relation to the concept of free volume in the amorphous phase.
Article
Physics, Fluids & Plasmas
E. A. Jagla
Summary: We present a two-dimensional mesoscopic model of a yield stress material that takes into account local volume fluctuations coupled to shear, resulting in a decrease in the material's shear strength as the local density decreases. The model successfully reproduces several well-known effects in the phenomenon of this type of material, including an increase in sample volume as deformation rate increases, non-45 degree orientation of shear bands with respect to the principal axis of applied stress, and instability of homogeneous deformation at sufficiently low deformation rates if the volume-shear coupling is strong enough. We also discuss the impact of this coupling on certain out-of-equilibrium configurations that are relevant to the study of shear bands observed in metallic glasses.
Article
Engineering, Mechanical
Yunlong Guan, Yunjiang Wang, Weidong Song
Summary: We propose an alternative strategy for modulating the mechanical properties of metallic glasses through introducing proper content of compositional or phase gradient. Molecular dynamics simulations demonstrate that phase gradient can increase the strength and improve the ductility of metallic glasses.
INTERNATIONAL JOURNAL OF MECHANICAL SCIENCES
(2022)
Article
Chemistry, Physical
Karina E. Avila, Vardan Hoviki Vardanyan, Stefan Kuechemann, Herbert M. Urbassek
Summary: Molecular dynamics simulations show a strong asymmetry in the response of bilayer systems with crystal-top and glass-top configurations, with the crystal-top system being the weakest and the glass-top system being the hardest. The presence of dislocations at the interface affects plastic activity and shear band formation differently in the two systems.
APPLIED SURFACE SCIENCE
(2021)
Article
Materials Science, Multidisciplinary
Zixiao Wang, Yingjie Yuan, Bingbing An
Summary: The film-substrate architectures show potential for improving the tensile ductility of metallic glasses. This study investigates the multiple cracking behavior of amorphous metallic glass films bonded to ductile substrates, taking into account factors such as pressure sensitive yielding and shear band induced cracking. The findings provide new insights for the design of reliable film-substrate systems.
INTERNATIONAL JOURNAL OF FRACTURE
(2022)
Article
Materials Science, Multidisciplinary
L. K. Zhang, D. Chen, C. G. Ye, L. C. Zhu, Y. Zhang
Summary: In this article, Cu45Zr45Ag7Al3 amorphous alloys were prepared using the copper mold suction casting method, and its three-point-bending fatigue performance was studied. The structural characteristics of the alloy were analyzed using X-ray diffraction (XRD), and the fatigue fracture morphology was analyzed using scanning electron microscopy (SEM). The results showed that the three-point-bending fatigue fracture surface morphology mainly consisted of three regions: the fatigue crack initiation region, the steady-state crack propagation region with typical fatigue stripes, and the final rapidly fracture region. The fatigue crack source was micropores ranging in size from 30 to 50 μm, where numerous shear bands formed. The fatigue limit of amorphous alloys was 410MPa, which was higher than the four-point-bending fatigue limit.
MATERIALS RESEARCH EXPRESS
(2023)
Article
Chemistry, Physical
Haixue Hou, Yuanyuan Chen, Lu Han, Panmei Liu, Zhang Liu, Zumin Wang
Summary: Graphene or graphene-like carbon-reinforced copper matrix composites have extensive application prospects in aerospace and electronic fields due to their high electrical, thermal conductivity and excellent machining performance. In this study, few-layer graphene (FLG) was synthesized by contacting amorphous carbon (a-C) with Cu at a low annealing temperature of 300 degrees C. The mechanism of low-temperature growth of graphene was investigated, and it was found that the formation of FLG is mediated by the diffusion of carbon atoms through the grain-boundary (GB), interfacial and surface diffusion. The Cu-induced growth of graphene at low temperatures may provide a promising support for synthesizing Cu/graphene composites in the future.
APPLIED SURFACE SCIENCE
(2022)
Article
Engineering, Mechanical
Ji Lin, Jin Qian, Yu Xie, Ji Wang, Rui Xiao
Summary: In this study, a micromechanical mean-field shear transformation zone (STZ) model is developed to systematically describe the stress responses of amorphous polymers. The model captures the behaviors of amorphous polymers in various loading conditions and successfully reproduces the Bauschinger effect. The deformation-induced material polarization, in the form of an anisotropic distribution of STZs, is identified as the governing mechanism of the Bauschinger effect.
INTERNATIONAL JOURNAL OF PLASTICITY
(2023)
Article
Physics, Condensed Matter
Ezequiel E. Ferrero, Eduardo A. Jagla
Summary: The study focuses on the strain load Delta gamma that triggers consecutive avalanches and the distribution of local distances to instability in amorphous solids, revealing the significant influence of system size on these characteristics.
JOURNAL OF PHYSICS-CONDENSED MATTER
(2021)
Article
Physics, Fluids & Plasmas
Bhanu Prasad Bhowmik, Michael Moshe, Itamar Procaccia
Summary: Recent progress in studying the physics of amorphous solids has shown that mechanical strains can be strongly screened by quadrupolar plastic events. This study provides direct measurements of the dipole field and demonstrates detailed agreement with the proposed theory. Measurements of the dipole fields can pinpoint the theory parameters that determine the profile of the displacement field.
Article
Nanoscience & Nanotechnology
Junjun Jia, Shimpei Iwasaki, Shingo Yamamoto, Shin-ichi Nakamura, Eisuke Magome, Toshihiro Okajima, Yuzo Shigesato
Summary: Understanding the crystallization mechanism of amorphous metal-oxide thin films is crucial for maintaining the stability of multifunctional flexible electronics. Experimental and theoretical analysis can be used to tune the crystal growth characteristics during crystallization process to optimize the electrical properties of materials, such as improving the carrier mobility of In2O3 films through crystallization.
ACS APPLIED MATERIALS & INTERFACES
(2021)