[SY-E13] Symposium E-13

[SY-E13] Molecular dynamics simulation of the interaction between grain boundary and point defects

^○Liang Zhang¹, Yasushi Shibuta¹, Cheng Lu² (1.The University of Tokyo, Japan, 2.University of Wollongong, Australia)

Molecular dynamics simulations were carried out to investigate the dynamic interaction between different grain boundaries (GBs) and two types of point defects, namely the stacking fault tetrahedron (SFT) and the void. The GB can migrate itself under the shear strain and can serve as a sink to remove SFT and void. The sink efficiency of GBs is sensitive to their structural characteristics, the size of point defects, and temperature. The high-angle GBs can show a great ability to remove the point defects even at a low temperature, while the increase of temperature can facilitate the annihilation of the point defects at the low-angle GBs. The simulation reveals a new possible GB-mediated damage healing mechanism of irradiated materials. In particular, the nanotwinned metals are generally anticipated to be less effective in the alleviation of radiation damage because they contain mostly coherent twin boundaries, which are low-energy boundaries and are inefficient defect sinks in irradiated metallic materials. However, recent in situ studies have indicated that some nanotwinned metals exhibit unprecedented radiation tolerance, and the unexpected self-healing of twin boundaries in response to radiation was observed. In this work, we proposed two possible self-healing mechanisms of twin boundaries by considering the defective coherent twin boundary structures which contained incoherent twin segments or self-interstitial atoms. The mechanisms were confirmed and atomistic evidence was provided by carrying out the long-time molecular dynamics simulations.