Two particles touch. Heat them, and atoms migrate into the contact point — the “neck” — welding the pair together. Pick a transport mechanism, set the temperature and particle size, and watch the initial-stage law (x/r)n = K·t play out. The magnifier zooms into the neck and shows which route the atoms take.
Mechanism
Temperature1100 °C
Particle radius
Neck ratio x/r: 0.00Rate vs 1100 °C: ×1.0Size handicap (Herring): baselineDensifying: no
Schematic teaching model. Initial-stage law (x/r)n = K(T)·t/rm with textbook exponents (surface diffusion n=7, m=4; grain-boundary diffusion n=6, m=4; evaporation–condensation n=3, m=2); K(T) follows an Arrhenius law with a representative activation energy Q = 300 kJ/mol. Time runs in reduced units and playback is speed-compressed so fast runs stay visible — the curve shape is exact; the law is drawn up to x/r ≈ 0.3, beyond which intermediate-stage models (e.g., Coble) apply. Moving dots in the magnifier illustrate the transport route schematically, not individual atom trajectories. Real kinetics depend on material, atmosphere, and geometry.