Heterogeneity in homogeneous nucleation from billion-atom molecular dynamics simulation of solidification of pure metal

Abstract

Can completely homogeneous nucleation occur? Large scale molecular dynamics simulations performed on a graphics-processing-unit rich supercomputer can shed light on this long-standing issue. Here, a billion-atom molecular dynamics simulation of homogeneous nucleation from an undercooled iron melt reveals that some satellite-like small grains surrounding previously formed large grains exist in the middle of the nucleation process, which are not distributed uniformly. At the same time, grains with a twin boundary are formed by heterogeneous nucleation from the surface of the previously formed grains. The local heterogeneity in the distribution of grains is caused by the local accumulation of the icosahedral structure in the undercooled melt near the previously formed grains. This insight is mainly attributable to the multi-graphics processing unit parallel computation combined with the rapid progress in high-performance computational environments.

Nucleation instability in supercooled Cu–Zr–Al glass-forming liquids

“…Classical molecular dynamics (MD) has become the main theoretical tool that allows investigating properties of supercooled liquids and glasses which are hardly available in experiments. The examples include short-range and mediumrange order [2,[14][15][16], dynamical heterogeneities [17][18][19][20], potential energy landscape [21][22][23][24] and nucleation mechanisms [25,26]. The key point of any MD simulation is the choice of interaction potential determining all the system properties at microscopic level.…”

Variational formulation of a quantitative phase-field model for nonisothermal solidification in a multicomponent alloy

“…However, recent advances in high-performance computing techniques have enabled large-scale phase-field simulations of the competitive growth of a bunch of dendrites [21][22][23]43,44]. Furthermore, molecular dynamics (MD) simulations have contributed to the estimation of the interfacial properties required for quantitative phase-field simulations [45,46] and large-scale MD simulations are now closing the gap in the knowledge between the microstructural and atomistic scales [47,48]. We believe that, coupled with these recent advances, the present quantitative phase-field model will contribute to further progress in our understanding of the formation processes of solidification microstructures.…”

A Molecular Dynamics Study of Partitionless Solidification and Melting of Al–Cu Alloys

“…It basically agrees with previous reports for other pure metals. 21,23) The linearly fitted lines for (100) and (110) orientations intersect with dotted line showing the solid-liquid interface velocity to be zero at 945 K. It is defined as the melting point of pure Al for this potential, which is close to the experimental value 933.47 K. Figure 4 illustrates the temperature dependence of the interfacial velocity for (100) and (110) orientations, respectively for pure Cu system in the same manner as pure Al system. The kinetic coefficients of the solid-liquid interface of Cu for (100) and (110) orientations are estimated to be 0.193 and 0.131 m/sK, respectively.…”