[SY-F12] Symposium F-12

[SY-F12] Microstructure formation in large-scale molecular dynamics simulation

Invited

^○Yasushi Shibuta¹, Shin Okita¹, Eisuke Miyoshi², Shinji Sakane², Tomohiro Takaki², Munekazu Ohno³ (1.The University of Tokyo, Japan, 2.Kyoto Institute of Technology, Japan, 3.Hokkaido University, Japan)

Microstructure formation is discussed on the basis of large-scale molecular dynamics (MD) simulations of nucleation, solidification and subsequent grain grow for pure iron [1-3]. After the nucleation and solidification, the time change of volume of grains is directly estimated for 2D and 3D grain growths [1]. For the 2D grain growth, grains with seven and more neighboring grains generally grow larger, whereas those with five and less neighboring grains shrink and disappear [2], which basically agrees with von Neumann-Mullins law. For the 3D grain growth, threshold number of neighboring grains is estimated to be approximately 14 [2]. Moreover, the physical origin of the deviation from the ideal grain growth is investigated by the direct estimation of the reduced mobility (i.e., the product of the intrinsic grain boundary mobility and the grain boundary energy) and the geometric factor [3]. The new insights based on large-scale MD simulations up to billion atoms are achieved for the first time owing to a multi-graphics processing unit (GPU) parallel computation on the GPU-rich supercomputer.

[1] Y. Shibuta, et al., Nature Comm. 8 (2017) 10. [2] S. Okita, Y. Shibuta, ISIJ Int. 56 (2016) 2199. [3] S. Okita et al., submitted.