Molecular Dynamics Simulation of Reduction of the Surface Layer Porosity in a BCC Crystal Induced by Laser Pulses

Abstract

A deeper understanding of the interaction of laser radiation with matter can facilitate the development of technologies for laser synthesis of materials with unique properties, nanostructuring of surfaces of processed solids, etc. The difficulties related to direct observations of various fast processes contribute to the progress in the computer simulation methods used to study them. This work presents the results of the simulation of reduction of the iron surface layer porosity induced by laser pulses. The investigations have been carried out using the potential calculated within the embedded atom method. The model under study has been subjected to structural analysis using the proven algorithms, which makes it possible to quantify the surface area of pores in the bulk of a crystal. The computational cells under consideration contain pores in the amorphous region, which remain stable upon the model cooling corresponding to the natural cooling of a solid in the environment described by a mathematical expression. Obviously, to get rid of defects, a solid should be annealed. It is shown that, after annealing at a temperature of no higher than half of the melting point, pores are preserved. Taking into account that the main mechanisms for reducing the porosity are the diffusion-viscous flow of matter into pores and that diffusion in the amorphous phase is more intense than in the crystalline one, the conditions for slowing down crystallization at a certain temperature should be established in the model. The required conditions have been achieved by straining the computational cell. It is shown that, as a result, the number of pores decreases under both compression and tension.