Heat and mass transfer under non-stationary external influence

Area of Science:

• Materials Science
• Physics
• Thermodynamics

Background:

• Pulsed thermal exposure, especially from giant laser pulses, significantly affects material properties.
• Understanding mass and heat transfer kinetics under extreme conditions is crucial for materials processing.
• Fick's law limitations in describing kinetic processes at high pulse power warrant investigation.

Purpose of the Study:

• To investigate mass and heat transfer phenomena in metals under high-energy pulsed laser excitation.
• To analyze structural changes in metals subjected to pulsed thermal exposure.
• To explore the role of dislocations in energy transfer during high-speed deformation.

Main Methods:

• Experimental studies of mass and heat transfer under pulsed power conditions.
• Analysis of structural changes induced by Q-switched laser pulses.
• Application of the Frenkel-Kontorova (FK) equation for dislocation energy transfer estimation.
• Utilizing the laser flash method for thermophysical studies.
• Calculation of Peierls stress.

Main Results:

• High-energy excitations of the crystal lattice were studied under small and large pulse power conditions.
• Accelerated mass and heat transfer processes share a common nature under high-speed metal deformation.
• Dislocations contribute to heat transfer, with energy estimates aligning with experimental laser flash method results.
• Fick's law is insufficient for describing kinetic processes at anomalously large pulse powers.

Conclusions:

• Directed dislocation flow contributes significantly to heat transfer, validated by the Frenkel-Kontorova equation and experimental data.
• The study provides insights into the mechanisms of mass and heat transfer under extreme pulsed thermal loads.
• Calculated Peierls stress offers further understanding of material behavior under these conditions.