Crystalline nucleation in undercooled liquid nickel

Filipponi, A.; Cicco, Andrea Di; Panfilis, Simone De; Giammatteo, Paolo; Iesari, Fabio

doi:10.1016/j.actamat.2016.10.076

Cited by 19 publications

(13 citation statements)

References 29 publications

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“…Figure 2(d) shows that the nucleation rate in pure Ni as a function of temperature. The nucleation rate computed with the persistent-embryo MD covers a wide undercooling range, which can be compared directly to the recent experimental measurements [23,24]. The results agree well with Bokeloh et al's experimental measurements from 1400 K to 1450 K, in which homogeneous nucleation was carefully probed [23].…”

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confidence: 80%

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Overcoming the Time Limitation in Molecular Dynamics Simulation of Crystal Nucleation: A Persistent-Embryo Approach

et al. 2018

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The crystal nucleation from liquid in most cases is too rare to be accessed within the limited time scales of the conventional molecular dynamics (MD) simulation. Here, we developed a "persistent embryo" method to facilitate crystal nucleation in MD simulations by preventing small crystal embryos from melting using external spring forces. We applied this method to the pure Ni case for a moderate undercooling where no nucleation can be observed in the conventional MD simulation, and obtained nucleation rate in good agreement with the experimental data. Moreover, the method is applied to simulate an even more sluggish event: the nucleation of the B2 phase in a strong glass-forming Cu-Zr alloy. The nucleation rate was found to be 8 orders of magnitude smaller than Ni at the same undercooling, which well explains the good glass formability of the alloy. Thus, our work opens a new avenue to study solidification under realistic experimental conditions via atomistic computer simulation.

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confidence: 80%

“…As there are no constraints in the embryos anymore, the critical nucleus indeed melted in half of the MD runs and grew in the other half runs, which further validates the determination of the critical nucleus size. measurements [24] from 1360 K to 1380 K but these data could be affected by possible heterogeneous nucleation [24].…”

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confidence: 99%

Overcoming the Time Limitation in Molecular Dynamics Simulation of Crystal Nucleation: A Persistent-Embryo Approach

et al. 2018

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“…Over the past few years, numerous direct or indirect research techniques have been developed to investigate the nucleation pathway, such as precipitation of minerals/protein from aqueous solution 17–19 , formation of colloidal crystals 20,21 , metal/alloys solidification 22,23 and oxide materials crystallization 24,25 . Although the formation and evolution of nuclei and pre-nucleation clusters have been observed directedly through colloidal particales 21 or HRTEM 17,18,23 , the indirect methods, such as heat events studies 26 , high-speed video camera 24 , microstructure studies 27,28 and computational simulations 29,30 are still the most widely used approaches for studying the nucleation path from extremely high temperature melt (especially undercooling melt).…”

Section: Introductionmentioning

confidence: 99%

Polymorphic transition and nucleation pathway of barium dititanate (BaTi2O5) during crystallization from undercooled liquid

et al. 2019

Sci Rep

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The nucleation pathway plays an important role in vitrification, preparation of glass-ceramic composites and synthesis of metastable materials. In this paper, we studied the nucleation pathway of a novel ferroelectric BaTi 2 O 5 (BT2) during crystallization from undercooled liquid by aerodynamic levitation (ADL) containerless processing and structural analysis. An interesting polymorphic transition of BT2 regulated by the undercooling was observed during the crystallization process: the ferroelectric monoclinic phase ( γ -BT2) was fabricated at low undercoolings and the paraelectric orthorhombic metastable phase ( β -BT2) was obtained from hypercooled liquid. This polymorphic transition phenomenon corresponds to a non-classical nucleation pathway: metastable β -BT2 preferentially nucleates from undercooled melt and γ -BT2 is generated from β phase by solid-state phase transition. The two-step nucleation pathway stems from the structural heredity between the undercooled liquid and crystals. A stronger structural homology exists between the undercooled melt and β -BT2 than γ -BT2 based on diffraction data and atomic configurations analysis. This structural homology coupled with nucleation barrier calculation was used to elucidate the non-classical nucleation pathway of BT2 crystallization: the similarity of the structural unit (Ti-O polyhedra) between the undercooled liquid and the metastable β -BT2 reduces the nucleation barrier and contributes to the preferential precipitation of β -like clusters. This work reveals the formation route of BT2 from cooling melt, which not only benefits the synthesis and application of this novel functional material but also provides a guideline of the crystallization process of titanates from melt at atomic level.

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“…Our interest in the generation of Poisson random numbers was motivated by the effort to develop a Kinetic Monte Carlo computer simulation of the classical nucleation process [17] and was required for an approximate treatment of the high transition rate region. The method has been recently applied to compute the homogeneous crystalline nucleation rate in undercooled liquid Ni [18] for comparison with experimental data. In the parameter range m ≤ 50, an efficient exact approach was adopted combining the method of Marsaglia [14], tabulated for integer parameter values, with a O(m) algorithm correction for the decimal part of m. While, for larger m, the following non-linear transformation from a standard Gaussian random number z, was adopted:…”

Section: Introductionmentioning

confidence: 99%

Wilson-Hilferty-type approximation for Poisson Random Variable

Giammatteo¹,

Mascio²

2020

Adv. sci. technol. eng. syst. j.

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The possibility to apply non-linear transformation of the Wilson-Hilferty type to the Poisson random variable is investigated using an analytic approach, in order to improve the convergence towards the large-parameter Gaussian limit. Considering the already existing non-linear transformation for the Gamma distribution, the original Wilson-Hilferty and a higher-order transformations are showed and approximations for the Gamma function are illustrated. From this, an approximate algorithm which exploits standard Gaussian random numbers is established, in order to generate Poisson random numbers of any parameter m. The algorithm performance is also assessed. The convenience of this approximate approach it resides in the fact that simulations often could be computationally demanding so that optimized algorithms have to be adopted for the efficient extraction of Poisson random numbers with variable parameter m.

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Crystalline nucleation in undercooled liquid nickel

Cited by 19 publications

References 29 publications

Overcoming the Time Limitation in Molecular Dynamics Simulation of Crystal Nucleation: A Persistent-Embryo Approach

Overcoming the Time Limitation in Molecular Dynamics Simulation of Crystal Nucleation: A Persistent-Embryo Approach

Polymorphic transition and nucleation pathway of barium dititanate (BaTi2O5) during crystallization from undercooled liquid

Wilson-Hilferty-type approximation for Poisson Random Variable

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