摘要
Metals in advanced nuclear reactors,such as W,often experience microcracks.However,the synergistic effects of high temperature,stress,and specialized structures can improve the self-healing ability of these metals.Microcrack healing is closely related to crack surface conditions.The order and disorder degree of crack surface atoms may affect crack stability.In this study,first-principles calculations,ab initio molecular dynamics,and surface thermodynamic theory were used to investigate the stability of grain boundary(GB)cracks at 0,293,and 373 K.We compared the energy densities,crack attraction energies,and atomic diffusion behaviors of crack surfaces atΣ3 GBs with those atΣ5 GBs.Adsorption on the nanocrack surface determines the critical nanocrack width.It was found that AlΣ3(111)nanocracks heal at high temperatures,and this healing behavior is closely related to the crack surface energy.Meanwhile,the GB cracks of W heal in an orderly manner at 573 and 1203 K.BY contrast,the GB cracks of Ti remain unhealed.Finally,a high-temperature nanocrack expansion model was developed and used to predict crack behavior under applied stress at different temperatures.
基金
supported by the National Natural Science Foundation of China(Nos.12175323,11832019,and 11705264)
project supported by the State Key Laboratory of Powder Metallurgy,Central South University,Guangdong Basic and Applied Basic Research Foundation(2023A1515012692)
the National Natural Science Foundation of China Original Exploration Project(12150001).
