关键词: 诱导凝固, 吉布斯-汤姆森效应, 固液界面能, 分子动力学模拟

Abstract:

Molecular dynamics (MD) simulation was applied to analyze the solidification of liquid Al induced by embedded solid nanoparticles with radii ranging from 0.37 to 2.4 nm. It was found that the critical temperature was proportional to the inverse of the nucleus radius, i.e., Gibbs-Thomson (G-T) effect, through which the G-T coefficient Γ and the bulk melting temperature T_m^bulk were obtained, 1.41.4*10^-7 Km and (985.36±11.25) K, respectively. The solid-liquid interfacial energy which was estimated (140.35±9.05)mJ/m² from Γ, was very close to the calculated 149 mJ/m² by capillary fluctuation method. It proved again that Turnbull underestimated this quantity experimentally (93 mJ/m²). The critical failure radius was extrapolated to be 0.91 nm. Meanwhile, the corresponding system temperature had reached the lower limit for the critical temperature, under which the system could be spontaneously nucleated, and the incubation time was somewhat random. Besides, the microstructure was characterized by the metastable cross stacking faults. When the embedded nucleus could serve as the nucleation core, the incubation time increased with increasing embedded nucleus radius. However, the growth rate decreased separately with the increasing embedded nucleus radius. The microstructure adopted the relatively stable lamellar structure.

Key words: induced solidification, Gibbs-Thomson (G-T) effect, solid-liquid interfacial energy, molecular dynamics (MD) simulation