Zhou LL, Pan JM, Lang L, Tian ZA, Mo YF, Dong KJ. Atomic structure evolutions and mechanisms of the crystallization pathway of liquid Al during rapid cooling.
RSC Adv 2021;
11:39829-39837. [PMID:
35494156 PMCID:
PMC9044542 DOI:
10.1039/d1ra06777j]
[Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2021] [Accepted: 11/29/2021] [Indexed: 01/09/2023] Open
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 Dp (D of the first peak), Hp increases monotonically; Wp, Dv, and Hv decrease monotonically; only Wv 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.
After nucleation, metastable HCP regions experience the following 3 stages: HCP–FCC transformation, region regularization, and dislocation pinning or HCP–FCC transformation again.![]()
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