Properties of Dislocation Drag from Phonon Wind at Ambient Conditions

Area of Science:

• Materials Science
• Condensed Matter Physics
• Solid Mechanics

Background:

• Dislocations are fundamental to plastic deformation.
• Dislocation mobility is influenced by interactions with the crystal lattice.
• Phonon wind, caused by phonon scattering off dislocations, significantly impedes dislocation motion at high temperatures and stresses.

Purpose of the Study:

• To investigate the functional dependence of dislocation drag coefficient (B) on dislocation velocity (v).
• To analyze this dependence across various regimes, from low velocities to near the transverse sound speed (cT).
• To establish an effective functional form for dislocation drag across different slip systems and dislocation characters.

Main Methods:

• Utilizing a semi-isotropic approach previously detailed in J. Phys. Chem. Solids (2019).
• Analyzing dislocation drag across a spectrum of velocities relative to the transverse sound speed (cT).
• Considering fixed room temperature and low pressure conditions.

Main Results:

• The study elucidates the approximate functional dependence of dislocation drag (B) on dislocation velocity (v).
• An effective functional form for B(v) is identified for diverse slip systems and dislocation characters.
• The findings are applicable to velocities up to the transverse sound speed (cT).

Conclusions:

• The phonon wind significantly impacts dislocation drag, especially at higher velocities.
• A generalized functional form for dislocation drag is established, applicable to various crystalline materials.
• This research provides crucial insights into the mechanisms governing plastic deformation in solids.