Investigation on cyclic deformation behaviour of silver bicrystals and their component crystals

Abstract

Cyclic deformation and fatigue crack initiation of silver bicrystals and component single crystals were discussed based on three aspects: (1) affected by the grain boundary (GB), the plateau stress of the bicrystal is slightly higher than that of any component crystal; (2) owing to the limitation of GB, dislocations pile up near GB, which simplifies the occurrence of secondary slip; and (3) cracks in bicrystals are more likely to form where persistent slip band (PSB) interacts with GB, rather than more advanced dislocation patterns such as cell and labyrinth structures. Therefore, the initiation priority of fatigue crack initiation in bicrystals is as follows: PSB-GB > PSB-PSB (cell or labyrinth) > PSB > vein.

KEYWORDS:

• Silver bicrystal
• grain boundary affected zone
• secondary slip
• dislocation pattern
• persistent slip band
• cell
• labyrinth
• crack initiation

Acknowledgements

The authors are grateful to H.H. Su, Q.Q. Duan, J.L.Wen and G. Yao for their assistance in the fatigue experiments and dislocation observations. This work is supported by the Alexander von Humboldt Foundation, the National Natural Science Foundation of China (NSFC) under grant number 51001104 and grant number 51331007, the National Basic Research Program of China under grant number 2017YFA0700704 and Yanshan University Scientific Research Foundation for Advanced Talents.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by the National Basic Research Program of China (973 Program) [grant number 2017YFA0700704] and the National Natural Science Foundation of China [grant number 51001104].