Three parallel algorithms for classical molecular dynamics are presented. The first assigns each processor a fixed subset of atoms; the second assigns each a fixed subset of inter-atomic forces to compute; the third assigns each a fixed spatial region. The algorithms are suitable for molecular dynamics models which can be difficult to parallelize efficiently—those with short-range forces where the neighbors of each atom change rapidly. They can be implemented on any distributed-memory parallel machine which allows for message-passing of data between independently executing processors. The algorithms are tested on a standard Lennard-Jones benchmark problem for system sizes ranging from 500 to 100,000,000 atoms on several parallel supercomputers--the nCUBE 2, Intel iPSC/860 and Paragon, and Cray T3D. Comparing the results to the fastest reported vectorized Cray Y-MP and C90 algorithm shows that the current generation of parallel machines is competitive with conventional vector supercomputers even for small problems. For large problems, the spatial algorithm achieves parallel efficiencies of 90% and a 1840-node Intel Paragon performs up to 165 faster than a single Cray C9O processor. Trade-offs between the three algorithms and guidelines for adapting them to more complex molecular dynamics simulations are also discussed.

Fast parallel algorithms for short-range molecular dynamics

Separating and recycling metal mixture of pyrolyzed waste printed circuit boards by a combined method.

Modification of the surface morphology of 4H-SiC by addition of Sn and Al in solution growth with SiCr solvents

Multi-phase-field lattice Boltzmann model for polycrystalline equiaxed solidification with motion

This paper reviews a current trend and recent progress in research on phase stability, atomic structures, mechanical and functional properties of high-entropy alloys. The survey is carried out based partly on the special issue published in April, 2020, in Materials Transactions (Vol. 61, No. 4). Research on high-entropy alloys has spread worldwide since the year of 2004, as many of them exhibit attractive properties for structural and functional applications, which have never been achieved in conventional alloys. Signi ﬁ cant progress has been made in recent years in our understanding of high-entropy alloys in terms of processing, characterization, modeling and simulation, and so on. Some of them are brie ﬂ y described in this paper. [doi:10.2320

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Recent Progress in Our Understanding of Phase Stability, Atomic Structures and Mechanical and Functional Properties of High-Entropy Alloys

Thermodynamic evaluation of the C-Cr-Si, C-Ti-Si, and C-Fe-Si systems for rapid solution growth of SiC

Time-resolved tomography (4D-CT) and X-ray diffraction (XRD) were combined to observe growing dendrites and to measure their crystallographic orientation in a CrMnFeCoNi high-entropy alloy with an FCC structure. The evolution of the dendritic grains cooling at 0.083K/s was reconstructed using 200 projections over a 180° rotation every 4 s from 4D-CT and a phase field filter. The voxel size was a 6.5μm cube. Simultaneously, the crystallographic orientations of the dendritic grains were measured by XRD. The dendrite arms grew preferentially along the ©100a direction, corresponding with typical FCC alloys. The specific solid­liquid interfacial area, which was normalized by the total volume, was evaluated as a function of solid fraction. The interfacial area reached a maximum at a solid fraction of 0.55. The interfacial area was compatible with the reported values of Al­Cu and Mg­Sn alloys. The secondary arm spacing was on the same order of magnitude as the spacing of conventional alloys. Overall, it appears that solidification in this high-entropy alloy can be analyzed by using models developed for binary or pseudo-binary alloys. [doi:10.2320/matertrans.MT-MK2019006]

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Characterization of Growing Dendrites in CrMnFeCoNi High-Entropy Alloy by Time-Resolved and In-Situ Tomography

/pdf/transformation-from-ferrite-to-austenite-during-after-40p3eqhe04.pdf

Transformation from Ferrite to Austenite during/after Solidification in Peritectic Steel Systems: an X-ray Imaging Study

Quantitative analysis of solidification of equiaxed grains in Al-Cu alloy refined by inoculant TiB2 particles with using time-resolved X-ray tomography

Taka Narumi

Papers

Thermodynamic evaluation of the C-Cr-Si, C-Ti-Si, and C-Fe-Si systems for rapid solution growth of SiC

Characterization of Growing Dendrites in CrMnFeCoNi High-Entropy Alloy by Time-Resolved and In-Situ Tomography

Transformation from Ferrite to Austenite during/after Solidification in Peritectic Steel Systems: an X-ray Imaging Study

Quantitative analysis of solidification of equiaxed grains in Al-Cu alloy refined by inoculant TiB2 particles with using time-resolved X-ray tomography

Solution growth of silicon carbide using unary chromium solvent