Modeling the early stages of reactive wetting

Area of Science:

• Materials Science
• Chemical Engineering
• Physics

Background:

• Experimental studies show molten metal droplet motion on reactive substrates is primarily inertial.
• Understanding high-temperature wetting and spreading is crucial for materials processing and microelectronics.

Purpose of the Study:

• To investigate wetting and spreading dynamics of molten metal droplets on reactive substrates under dominant inertial effects.
• To model the behavior of a binary three-phase material using a thermodynamically derived diffuse interface approach.

Main Methods:

• Utilized a diffuse interface model incorporating van der Waals approach for liquid-vapor and phase field for solid-fluid transitions.
• Simulated droplet spreading, analyzing triple-line motion, spreading rates, and dissolution effects.
• Examined dissipation mechanisms using the entropy-production field.

Main Results:

• Demonstrated an O(t(-1/2)) spreading rate during the inertial regime.
• Observed triple-line oscillations during the transition from inertial to diffusive spreading.
• Found that enhanced dissolution, by manipulating liquid composition, reduces spreading extent.
• Model results show good agreement with experiments, particularly copper on silicon.

Conclusions:

• Spreading extent and rate are governed by the spreading coefficient derived from interface energies.
• Dissipation mechanisms shift from the triple-line region (inertial stage) to the solid-liquid interface (diffusive stage).
• The diffuse interface model provides a valuable tool for understanding high-temperature droplet spreading phenomena.