Limiting velocities and transonic dislocations in Mg

Abstract

To accurately predict the mechanical response of materials, especially at high strain rates, it is important to account for dislocation velocities in these regimes. Under these extreme conditions, it has been hypothesized that dislocations can move faster than the speed of sound. However, the presence of such dislocations remains elusive due to challenges associated with measuring these experimentally. In this work, molecular dynamics simulations were used to investigate the dislocation velocities for the basal edge, basal screw, prismatic edge, and prismatic screw dislocations in Mg in the sub-, trans-, and supersonic regimes. Our results show that only prismatic edge dislocations achieve supersonic velocities. Furthermore, this work demonstrates that the discrepancy between the theoretical limiting velocity and the MD results for Mg is due to its sensitivity to large hydrostatic stress around the dislocation core, which was not the case for fcc metals such as Cu.

7 pages, 4 figures; v2 clarifications and additional results

References in corpus (4)

• Analytic model of the remobilization of pinned glide dislocations: including dislocation drag from phonon wind
• Dislocation drag and its influence on elastic precursor decay
• Clarifying the definition of 'transonic' screw dislocations
• A general solution for accelerating screw dislocations in arbitrary slip systems with reflection symmetry

Cited by in corpus (5)

• Exploring the relation between transonic dislocation glide and stacking fault width in FCC metals
• 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