嵌入纳米Fe颗粒的Fe液凝固过程的分子动力学模拟

采用Sutton-Chen 势函数及分子动力学(MD)方法对嵌入了Fe纳米团簇(半径从0.4-1.8 nm)的Fe液凝固过程进行了模拟. 模拟结果表明只有当嵌入的纳米团簇半径超过0.82 nm才能降低凝固时所需要的临界过冷度(ΔT^*), 起到诱导凝固的作用. 同时采用原子键型指数法(CTIM-2)对样本在凝固过程中的原子结构进行了标定, 通过观察微观结构演变发现当嵌入纳米团簇能够作为凝固核心时, 体系按照hcp-fcc 交叉形核的方式长大. 同时还发现嵌入纳米团簇对体系凝固过程晶核的生长方向及凝固的最终构型存在“结构遗传效应”.

Solidification of Liquid Fe with Embedded Homogeneous Solid Fe Nanoparticles from Molecular Dynamics Simulations

Solidification processes of liquid Fe with embedded homogeneous solid nanoparticle whose radius ranges from 0.4 to 1.8 nm have been studied by molecular dynamics simulation adopting the Sutton-Chen potential. It was found that the particles whose radii exceed 0.82 nm can obviously decrease the critical undercooling (ΔT^*) and induce solidification. The microstructural evolution during the solidification process is traced through the atom definition with cluster-type index method (CTIM-2). Results revealed that when the embedded particle induced solidification, the growth process of nucleus would proceed as a cross-nucleation between hcp and fcc structures, a little similar to the eutectic crystallization process. Moreover, the heredity effect attributed by embedded solid nanoparticle is clearly observed during the microstructural evolution.