Atomic structure evolutions and mechanisms of the crystallization pathway of liquid Al during rapid cooling. Issue 63 (14th December 2021)

• Record Type: Journal Article
• Authors: Zhou, Li-li; Pan, Jia-ming; Lang, Lin; Tian, Ze-an; Mo, Yun-fei; Dong, Ke-jun
• Is Part Of: RSC advances. Volume 11:Issue 63(2021)
• Page Start: 39829
• Page End: 39837
• Publication Date: 2021-12-14
• Subjects: Chemistry -- Periodicals; 540.5
• DOI: 10.1039/d1ra06777j
• Languages: English
• ISSNs: 2046-2069

Abstract

Abstract : After nucleation, metastable HCP regions experience the following 3 stages: HCP–FCC transformation, region regularization, and dislocation pinning or HCP–FCC transformation again. Abstract : The solidification of pure aluminum has been studied by a large-scale molecular dynamic simulation. The potential energy, position D, height H, and width W of the first peak and valley of PDF curves, and the local structures were investigated. It was found that the FCC-crystallization ability of pure Al is so strong that still local crystal regions exist in the amorphized solid. As the temperature decreases, besides the counter-intuitive increase in D p ( D of the first peak), H p increases monotonically; W p, D v, and H v decrease monotonically; only W v first decreases and then increases. They all change critically when phase transition happens. After the nucleation, orientation-disordered HCP-regions, as the grain boundaries or defects of FCC crystals, rapidly transform into FCC structures, and then the surviving HCP-regions regularize into few parallel layers or orientation-disordered HCP-regions. If parallel layers result in dislocation pinning, structural evolution terminates; otherwise, it continues. These findings will have a positive impact on the development of the solidification and nucleation theory.