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MM: Fachverband Metall- und Materialphysik

MM 50: Methods in Computational Materials Modelling II: Microstructure evolution

MM 50.4: Vortrag

Donnerstag, 10. März 2016, 11:00–11:15, H53

Laser Ablation of Alloys and Layered Materials — •Johannes Roth¹, Dennis Rapp², Alexander Kiselev¹, and Hans-Rainer Trebin¹ — ¹FMQ, Universität Stuttgart — ²IWMF, Universität Stuttgart

We have studied laser ablation of Al-Ni alloys and layers using MD simulations combined with a two-temperature model (TTM) to describe the influence of the electrons. First the simulation program had to be adapted to alloys and the parameters for the electronic contribution had to be determined. After tests with pure Al and Ni melting depths and ablation thresholds for AlNi, AlNi₃ and Al₃Ni have been determined. For AlNi₃ we observe a change in ablation mechanism at high fluences and for the orthorhombic Al₃Ni a phase transition to a cubic L1₂ phase. Unfortunately there are nearly no experimental data avaialable to compare with.

Al layers on Ni substrates have also been studied. A thin layer of Al melts first, the Ni substrate follows, then the Al is ablated completely. A thicker Al layer absorbs a lot of laser energy and delays the melting of the Ni substrate to considerably higher fluences. At fluences low above the ablation threshold the thick Al layer is ablated as a whole as before, but at higher fluence the ablation depth is reduced due to vaporization of Al which cools the sample. The diffusion assisted formation of AlNi alloys has been observed in the thin layer case for fluences close to the ablation threshold. The structure of the compounds is fcc as in AlNi, but the composition varies from pure molten Al to solid Ni.