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采用所构建的长程F-S势函数,对连续升温过程中γ-Fe→δ-Fe→液态Fe的相变过程进行了分子动力学(MD)模拟。结果表明,计算得到的γ-Fe,δ-Fe以及液态Fe的微观结构(径向分布函数、配位数)和宏观物性(密度)都能与实验结果吻合很好,但相变温度点与实验值的偏差较大,推测是由过快升温速度造成的过热度过高所致,从微观结构、瞬态能量及密度的分析出发,讨论了固态相变(γ-Fe→δ-Fe)和固-液相变(δ-Fe→液态Fe)的具体过程,其中,固态相变主要形成于晶格扭曲和滑移,而固-液相变即熔化过程起始于固体岛颗粒的边缘,并逐渐向其中心扩散,在相变演化过程中,通过瞬态能量和密度的起伏观察到明显的孕育过程。
Using the constructed long-range F-S potential function, the molecular dynamics (MD) simulation of the phase transformation of γ-Fe → δ-Fe → liquid Fe during continuous heating was carried out. The results show that the calculated microstructure (radial distribution function, coordination number) and macroscopic physical properties (density) of γ-Fe, δ-Fe and liquid Fe all agree well with the experimental results. The deviation of the experimental values is large, which is presumed to be caused by the excessively high superheating rate caused by the excessive heating rate. Based on the analysis of the microstructure, transient energy and density, the solid state transformation (γ-Fe → δ-Fe) And solid-liquid phase transition (δ-Fe → liquid-phase Fe), in which the solid-state phase transformation mainly forms in the lattice distortion and slippage, and the solid-liquid phase transformation, ie, the melting process, begins at the edge of the solid island particles , And gradually spread to its center. During the process of phase transformation, obvious inoculation process was observed through the fluctuation of transient energy and density.