Submicron plasticity: yield stress, dislocation avalanches, and velocity distribution

Abstract

The existence of a well defined yield stress, where a macroscopic piece of crystal begins to plastically flow, has been one of the basic observations of materials science. In contrast to macroscopic samples, in micro- and nanocrystals the strain accumulates in distinct, unpredictable bursts, which makes controlled plastic forming rather difficult. Here we study by simulation, in two and three dimensions, plastic deformation of submicron objects under increasing stress. We show that, while the stress-strain relation of individual samples exhibits jumps, its average and mean deviation still specify a well-defined critical stress, which we identify with the jamming-flowing transition. The statistical background of this phenomenon is analyzed through the velocity distribution of short dislocation segments, revealing a universal cubic decay and an appearance of a shoulder due to dislocation avalanches. Our results can help to understand the jamming-flowing transition exhibited by a series of various physical systems.

5 pages

References in corpus (5)

• Crackling Noise
• Intermittent dislocation flow in viscoplastic deformation
• Strain bursts in plastically deforming Molybdenum micro- and nanopillars
• Fluctuation phenomena in crystal plasticity - a continuum model
• Dislocation Glasses: Aging during Relaxation and Coarsening

Cited by in corpus (23)

• Dislocation-mediated growth of bacterial cell walls
• Dislocation evolution during plastic deformation: Equations vs. discrete dislocation dynamics study
• Quenched pinning and collective dislocation dynamics
• A minimal integer automaton behind crystal plasticity
• The Universality Class of Nano-Crystal Plasticity: Self-Organization and Localization in Discrete Dislocation Dynamics
• Mesoscale model of dislocation motion and crystal plasticity
• On the critical nature of plastic flow: one and two dimensional models
• Comparison of the dislocation density obtained by HR-EBSD and X-ray profile analysis
• Dislocations Jam At Any Density
• Determination of the universality class of crystal plasticity
• Scale-free phase field theory of dislocations
• Criticality of relaxation in dislocation systems
• Micro-plasticity and intermittent dislocation activity in a simplified micro structural model
• A probabilistic explanation for the size-effect in crystal plasticity
• Anisotropic velocity statistics of topological defects under shear flow
• Intermittent dislocation density fluctuations in crystal plasticity from a phase-field crystal model
• The Emergence and Role of Dipolar Dislocation Patterns in Discrete and Continuum Formulations of Plasticity
• The role of weakest links and system size scaling in multiscale modeling of stochastic plasticity
• Plastic strain is a mixture of avalanches and quasi-reversible deformations: Study of various sizes
• Avalanches, Plasticity, and Ordering in Colloidal Crystals Under Compression
• An efficient implicit method for discrete dislocation dynamics simulations
• Avalanche correlations and stress-strain curves in discrete dislocation plasticity
• Efficient numerical method to handle boundary conditions in 2D elastic media