Phase-field modeling of crystal nucleation in undercooled liquids


László Gránásy,a,b Gyula I. Tóth,c James A. Warren,d Frigyes Podmaniczky,a György Tegze,a László Rátkai,a Tamás Pusztai a

In a recent article appeared in the prestigious journal Progress in Materials Science (impact factor 23.725), researchers from the Wigner Research Centre for Physics (Hungary), the Loughborough University (UK), and the National Institute of Standards and Technology (US) review how phase-field theoretical studies contributed to the understanding of crystal nucleation in undercooled liquids. Crystal nucleation, i.e., the stochastic formation of crystal seeds via random fluctuations, plays a central role in various branches of science including materials science, chemical physics, cryobiology, atmospheric sciences, geophysics, etc. Besides the molecular- and mesoscale models, a broad range of phenomena are addressed in the review including the stages of the crystalline ordering, nucleation in eutectic and phase separating systems, phase selection via competing nucleation processes, growth front nucleation (a process, in which crystal grains of new orientations form at the growth front) yielding crystal sheaves and spherulites, and the transition between the growth controlled cellular and the nucleation dominated equiaxed solidification morphologies. A few interesting cases are displayed by the computer animations shown below (Figs. 1 – 3).
  a1    1b

                     1a                                                                            1b
Fig. 1: Phase-field modelling of microstructures forming in Al-Ti alloy on the mesoscale. (a) Columnar, (b) equiaxed structures.

2a
2a

  2b   2c

2b                                                                                       2c
Fig. 2: Heterogeneous nucleation in the mesoscale phase-field model at foreign surfaces under boundary conditions that ensure contact angles of (a) 30, (b) 90, and (c) 120 degrees at the solid-liquid-foreign wall trijunction. 


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Fig. 3: Structural analysis of two-step crystal nucleation in molecular scale phase-field modelling. The white, red, and green colours denote amorphous local structure, medium range crystallike structural order, and base centred cubic crystal, respectively. 


a Wigner Research Centre for Physics, P.O. Box 49, H-1525 Budapest, Hungary
b Brunel Centre of Advanced Solidification Technology, Brunel University, Uxbridge, Middlesex UB8 3PH, UK
c Department of Mathematical Sciences, Loughborough University, Loughborough, Leicestershire LE11 3TU, UK
d National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA

Link to the paper: https://www.sciencedirect.com/science/article/pii/S0079642519300453

This work was supported by the "Frontline" excellence programme of the National Research, Development and Innovation Office (Hungary).