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.

中文翻译：

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激光脉冲诱导 BCC 晶体表面层孔隙率减少的分子动力学模拟

摘要

更深入地了解激光辐射与物质的相互作用可以促进激光合成具有独特性能的材料、加工固体表面的纳米结构等技术的发展。与直接观察各种快速过程相关的困难有助于在用于研究它们的计算机模拟方法。这项工作提出了激光脉冲引起的铁表面层孔隙率减少的模拟结果。研究是使用嵌入原子方法计算的电势进行的。所研究的模型已经使用经过验证的算法进行了结构分析，这使得量化晶体主体中孔隙的表面积成为可能。所考虑的计算单元在非晶区域中包含孔，这些孔在模型冷却时保持稳定，该模型冷却对应于数学表达式所描述的环境中固体的自然冷却。显然，为了消除缺陷，固体应该进行退火。结果表明，在不高于熔点一半的温度下退火后，孔得以保留。考虑到降低孔隙率的主要机制是物质进入孔隙的扩散粘性流动，且非晶相中的扩散比晶相中的扩散更强烈，因此应建立在一定温度下减缓结晶的条件在模型中。通过对计算单元进行应变已达到所需的条件。结果表明，在压缩和拉伸情况下，孔隙数量都会减少。