Article
Materials Science, Multidisciplinary
Emile Maras, Emmanuel Clouet
Summary: The plasticity in hexagonal close-packed zirconium is controlled by screw dislocations, which easily glide in prismatic planes and occasionally across-slip in other planes at high temperatures. Molecular dynamics simulations reveal a combination of prismatic and pyramidal slip in the high stress regime, with basal slip favored at low stress levels due to a change in the glide mechanism.
Article
Nanoscience & Nanotechnology
Christian Brandl, In-Chul Choi, Ruth Schwaiger
Summary: The thermally activated plasticity of body-centered cubic (BCC) metals was investigated through high-temperature nanoindentation, revealing the change in slip plane as a result of dislocation kink pair formation with increasing temperature.
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
(2022)
Article
Engineering, Mechanical
Wenbin Liu, Lirong Chen, Long Yu, Jiaqi Fu, Huiling Duan
Summary: A continuum crystal plasticity framework incorporating a stochastic distribution model of critical resolved shear stress (CRSS) is developed to describe the formation of dislocation channels and further plastic flow localization in irradiated materials. The stochastic model successfully simulates the dislocation channel formation and plasticity localization in both irradiated single and polycrystalline copper (Cu), providing new insights for the study of plasticity localization in metals.
INTERNATIONAL JOURNAL OF PLASTICITY
(2022)
Article
Materials Science, Multidisciplinary
Yang Li, Giacomo Po, Yinan Cui, Nasr Ghoniem
Summary: In this study, three-dimensional dislocation ensembles in Zr pillars are modeled using newly developed mobility laws for dislocations on prismatic and basal planes. The effects of loading orientation and temperature on the micro-scale mechanical response of single crystals are systematically investigated. It is found that the transition from prismatic to basal glide of dislocation ensembles can be controlled by selecting the sample temperature and loading orientation.
Article
Materials Science, Multidisciplinary
Yilun Xu, Felicity F. Worsnop, David Dye, Fionn P. E. Dunne
Summary: The slip intermittency and stress oscillations observed in titanium alloy Ti-7Al-O are investigated using a discrete dislocation plasticity model. The results show that these phenomena are caused by dislocation escape during stress holds, governed by a thermal activation constitutive law. The stress drops due to basal slip are larger than those along prism due to their differing rate sensitivities, which has been previously observed in micropillar testing. It is suggested that interstitial oxygen suppresses stress oscillations by inhibiting the thermal activation process. Understanding these mechanisms is important for the design and safety assessment of jet engine titanium alloys subjected to dwell fatigue.
JOURNAL OF THE MECHANICS AND PHYSICS OF SOLIDS
(2023)
Article
Materials Science, Multidisciplinary
Wenzhen Xia, Piyush Pramod Patil, Chang Liu, Gerhard Dehm, Steffen Brinckmann
Summary: The tribology induced microstructure plays a key role in determining the tribological properties of metals. Single nano-/microasperity sliding tests have enabled the investigation of plastic evolution during the initial stages of wear, but the formation mechanisms of sliding induced grain refinement are still largely unknown. In this study, a novel microwall sliding test was conducted to simplify the stress state and directly inspect the contact zone. The formation of a misorientation jump in the crystal orientation below the wear track was observed, leading to the formation of large angle grain boundaries.
Article
Materials Science, Multidisciplinary
M. Longsworth, M. Fivel
Summary: The cross-slip rate of screw segments in dislocation dynamics simulations was calculated using a model based on the harmonic transition state theory and the Meyer-Neldel rule. The results were in quantitative agreement with atomistic simulations.
JOURNAL OF THE MECHANICS AND PHYSICS OF SOLIDS
(2021)
Article
Materials Science, Multidisciplinary
Yang Li, Sabyasachi Chatterjee, Enrique Martinez, Nasr Ghoniem, Giacomo Po
Summary: In the model, basal-to-prismatic cross-slip is energetically favorable, while prismatic-to-basal cross-slip is only activated under specific conditions. The proposed mechanism for basal slip of <a> screw dislocations in Zr involves the formation and lateral migration of kink pairs formed by double cross-slip.
Review
Materials Science, Multidisciplinary
Jian Wang, Amit Misra
Summary: Heterostructured materials composed of nanoscale phases can enhance both yield strength and strain hardening, leading to uniform distribution of plastic flow. Deformation mechanisms in nanoscale eutectic binary systems enable slip transmission and interface-enabled plasticity, explaining the strength-ductility relationship and distributed plastic flow in multi-component eutectics.
CURRENT OPINION IN SOLID STATE & MATERIALS SCIENCE
(2023)
Article
Materials Science, Multidisciplinary
Qun Yang, Yang Hu, Jian-Min Zuo
Summary: This study examined the dislocation structure of slip bands in high entropy alloy (HEA) nanopillars oriented for single slip, providing experimental evidence on the dislocation organization in a slip band and comparing the results with previously proposed models. The unique aspects of HEA that enable such observations were investigated through an examination of the dislocation microstructure and its response to applied forces in the nanopillars.
JOURNAL OF MATERIALS SCIENCE & TECHNOLOGY
(2021)
Article
Chemistry, Physical
Laszlo Z. Toth, Lajos Daroczi, Tarek Y. Elrasasi, Dezso L. Beke
Summary: The results of acoustic emission measurements during plastic deformation of polycrystalline Sn samples are analyzed using the adaptive sequential k-means method. The acoustic avalanches are separated based on their spectral properties and presented on feature space plots and power spectral density curves. The clustering analysis is able to eliminate background noise and accurately distinguish between different acoustic emission sources.
Article
Materials Science, Multidisciplinary
Ronan Madec, Luc Portelette, Bruno Michel, Jonathan Amodeo
Summary: The mechanical behavior of UO2 single crystal, especially the unexpected multi-slip observations, has been studied in this research. A multi-scale model based on composite slip is proposed, in which dislocation density can be transferred from primary slip systems to secondary systems under the effect of cross-slip. This approach accurately describes the anisotropic mechanical response of UO2 single crystal, providing new insights into the links between dislocation microstructures and mechanical properties. The composite slip mechanism appears to be a candidate for explaining unexpected plastic behaviors in complex materials with multiple slip modes, suggesting that slip activation may be more complex than in usual constitutive laws.
Article
Multidisciplinary Sciences
Yifan Wang, Wei Cai
Summary: This study reveals the microscopic mechanisms of cross-slip of screw dislocations in crystalline solids using molecular dynamics simulation and identifies the influence of anharmonic effects. This finding contributes to a better understanding of stress-driven thermally activated processes in solids.
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
(2023)
Article
Materials Science, Multidisciplinary
Andrew J. Birnbaum, Anna K. Rawlings, John C. Steuben, Athanasios Iliopoulos, John G. Michopoulos
Summary: This study aims to investigate the mechanism of plastic strain generation in nickel single crystals during laser processing. The use of ultra-high purity nickel single crystals simplifies the analysis by minimizing dislocation interactions with grain boundaries or solutes.
Review
Crystallography
Khanh Nguyen, Meijuan Zhang, Victor Jesus Amores, Miguel A. Sanz, Francisco J. Montans
Summary: The bridge between classical continuum plasticity and crystal plasticity is narrowing due to improved computational power and engineers' desire for more accurate simulations including microstructure effects. This paper provides an overview of current techniques used in crystal plasticity formulations for finite element analysis, serving as a starting point for researchers looking to incorporate microstructure effects in elastoplastic simulations. Both classical and novel crystal plasticity formulations, as well as approaches to model dislocations in crystals, are discussed.