MOLECULAR DYNAMICS SIMULATION OF THE REDUCTION IN POROSITY OF THE SURFACE LAYER OF A BCC CRYSTAL CAUSED BY INFLUENCE OF LASER PULSES

10.25712/ASTU.1811-1416.2024.02.003

Abstract

Under the influence of laser pulses, significant changes in the microstructure of the surface layers of materials are possible; in particular, an extended dislocation layer can be observed under the irradiated surface. At the same time, various mechanisms for the formation of dislocations in this case are proposed. Obviously, a more complete understanding of the root causes of the occurrence of dislocations is an urgent task and its solution can find its practical application. The complexity of direct observations of the processes under study does not allow for a comprehensive study, therefore, in this case, numerical experiments using computer modeling are successfully used. This paper presents the results of modeling structural changes that occur when simulating the impact of laser pulses with different energy densities on the surface of an iron crystal, and which are accompanied by the formation of dislocations. The model is based on an approximation that assumes that laser exposure only leads to heating of the irradiated material. To carry out the study, the molecular dynamics method was used using the interparticle interaction potential calculated within the framework of the embedded atom method. During the simulation, an interphase boundary appeared in the computational cell, which is a source of mechanical stress. Its peculiarity is the presence of surface curvature, leading to uneven stress distribution. It is suggested that it is precisely due to this that the necessary conditions for the formation of dislocations are created. The work visualizes the process of nucleation and subsequent growth of dislocations, as well as the dislocation reaction. The changes in the length of dislocations have been assessed for various variations of initial conditions and modeling parameters. Perhaps the results of the study will find their application in describing the processes that occur during high-energy exposure to a solid body.