Material decomposition mechanisms in femtosecond laser interactions with metals

M. E. E. Povarnitsyn (1) , Tatiana Itina (1) , Marc Sentis (1) , K. V. Khishchenko , P. Levashov

1 LP3 - Laboratoire Lasers, Plasmas et Procédés photoniques

A numerical hydrodynamic study of femtosecond laser ablation is presented. A detailed analysis of material decomposition is performed using a thermodynamically complete equation of state with separate stable and metastable phase states and phase boundaries. The lifetime of the metastable liquid state is estimated based on the classical theory of homogeneous nucleation. In addition, mechanical fragmentation of the target material is controlled based on available criteria. As a result, several ablation mechanisms are observed. A major fraction of the ablated material, however, is found to originate from the metastable liquid region, which is decomposed either thermally in the vicinity of the critical point into a liquid-gas-mixture or mechanically at high strain rate and negative pressure into liquid droplets and chunks. The calculation results explain available experimental findings.

Mots clés: aluminium; decomposition; laser ablation; metastable states; nucleation; phase diagrams; critical points; phase separation

Domaines: Génie des procédés

M. E. E. Povarnitsyn, Tatiana Itina, Marc Sentis, K. V. Khishchenko, P. Levashov. Material decomposition mechanisms in femtosecond laser interactions with metals. Physical Review B: Condensed Matter and Materials Physics (1998-2015), 2007, 75, pp.235414. ⟨10.1103/PhysRevB.75.235414⟩. ⟨ujm-00376970⟩