Velocity dependent dislocation drag from phonon wind and crystal geometry

Abstract

The mobility of dislocations is an important factor in understanding material strength. Dislocations experience a drag due to their interaction with the crystal structure, the dominating contribution at high stress and temperature being the scattering off phonons due to phonon wind. Yet, the velocity dependence of this effect has eluded a good theoretical understanding. In a previous paper, dislocation drag from phonon wind as a function of velocity was computed from first principles in the isotropic limit, in part for simplicity, but also arguing that macroscopically, a polycrystalline metal looks isotropic. However, since the single crystal grains are typically a few microns up to a millimeter in size, dislocations travel in single crystals and cross boundaries, but never actually see an isotropic material. In this work we therefore highlight the effect of crystal anisotropy on dislocation drag by accounting for the crystal and slip plane geometries. In particular, we keep the phonon spectrum isotropic for simplicity, but dislocations are modeled according to the crystal symmetry (bcc, fcc, hcp, etc.). We then compare to the earlier purely isotropic results, as well as to experimental data and MD simulations where they are available.

25 pages, 9 figures; v2 revised/expanded, v3-5 improved presentation

References in corpus (3)

• Supersonic dislocations observed in a plasma crystal
• Line tension of a dislocation moving through an anisotropic crystal
• Averaging of elastic constants for polycrystals

Cited by in corpus (16)

• Dislocation drag from phonon wind in an isotropic crystal at large velocities
• Analytic model of the remobilization of pinned glide dislocations: including dislocation drag from phonon wind
• Properties of dislocation drag from phonon wind at ambient conditions
• Dislocation drag and its influence on elastic precursor decay
• Clarifying the definition of 'transonic' screw dislocations
• Limiting velocities and transonic dislocations in Mg
• On the temperature and density dependence of dislocation drag from phonon wind
• How to determine limiting velocities of dislocations in anisotropic crystals
• A general solution for accelerating screw dislocations in arbitrary slip systems with reflection symmetry
• The scattering of phonons by infinitely long quantum dislocations segments and the generation of thermal transport anisotropy in a solid threaded by many parallel dislocations
• Exploring the relation between transonic dislocation glide and stacking fault width in FCC metals
• Dynamic Peach-Koehler self-force, inertia, and radiation damping of a regularized dislocation
• Comparing theoretical predictions of radiation-free velocities of edge dislocations to molecular dynamics simulations
• Properties of accelerating edge dislocations in arbitrary slip systems with reflection symmetry
• PyDislocDyn: A Python code for calculating dislocation drag and other crystal properties
• Computationally efficient method for determining limiting velocities of edge dislocations in anisotropic crystals