Laser ablation of Al–Ni alloys and multilayers

Abstract

Laser ablation of Al-Ni alloys and multilayers has been studied by molecular dynamics simulations. The method was combined with a two-temperature model to describe the interaction between the laser beam, the electrons, and the atoms. As a first step, electronic parameters for the alloys had to be found and the model developed originally for pure metals had to be generalized to multilayers. The modifications were verified by computing melting depths and ablation thresholds for pure Al and Ni.Here known data could be reproduced. The improved model was applied to the alloys Al 3 Ni, AlNi and AlNi 3 . While melting depths and ablation thresholds for AlNi behave unspectacular, sharp drops at high fluences are observed for Al 3 Ni and AlNi 3 . In both cases, the reason is a change in ablation mechanism from phase explosion to vaporization. Furthermore, a phase transition occurs in Al 3 Ni. Finally, Al layers of various thicknesses on a Ni substrate have been simulated. Above threshold, 8 nm Al films are ablated as a whole while 24 nm Al films are only partially removed. Below threshold, alloying with a mixture gradient has been observed in the thin layer system.

Continuous Demixing Transition of Binary Liquids: Finite‐Size Scaling from the Analysis of Sub‐Systems

“…by virtue of the definition of 𝜒 𝓁 analogous to Equation ( 6), with ⟨N 𝓁 ⟩ = 𝜌𝓁 d , and using Equation (12) in the second step. For every value of y = 𝓁∕𝜉, the ŷ-integral yields a constant f 2 (y).…”

“…In the past decade, the seemingly never ending growth in computing power was, among other factors, driven by a shift to massive parallelization, making molecular simulations of unprecedented system sizes and run lengths broadly available. [7][8][9][10][11][12][13] The use of huge systems mitigates artifacts due to a finite simulation box and allows, in principle, probing the critical divergences directly as one would do in an experiment. Yet, an elegant and conceptually superior alternative exploits the scale invariance of the critical fluid and turns the limitation of a finite system size into an advantage by explicitly following the divergences of certain fluid properties as a function of the system size.…”

Laser Ablation of Al-Ni Alloys and Al-Ni Layer Systems simulated with Molecular Dynamics and the Two-Temperature Model

“…Details of the laser ablation and laser induced melting have been presented in [18]. The pure phases and alloys Al, AlNi and AlNi 3 are cubic.…”

“…Details of this work have been published already [18]. Therefore the method and results will only shortly be summarized.…”

Continuous demixing transition of binary liquids: finite-size scaling from the analysis of sub-systems

“…In the past decade, the seemingly never ending growth in computing power was, among other factors, driven by a shift to massive parallelisation, making molecular simulations of unprecedented system sizes and run lengths broadly available [7][8][9][10][11][12][13] . The use of huge systems mitigates artifacts due to a finite simulation box and allows, in principle, probing the critical divergences directly as one would do in an experiment.…”