Effects of accommodated grain boundary sliding on triple junction nanovoid nucleation in nanocrystalline materials

A theoretical model is suggested to investigate the effect of grain boundary (GB) sliding with GB diffusion accommodation on triple junction nanovoids nucleation in deformed nanocrystalline materials. Within our description, at high strain rate, nanovoids are nucleated due to GB sliding which is non-accommodated at comparatively low temperature and effectively accommodated by GB diffusion process at elevated temperature. In this paper, the corresponding energy characteristics of the pile-up of GB dislocations caused by GB sliding and GB diffusion are calculated, respectively. Then, the nucleation of nanovoid at triple junctions is studied and the equilibrium radius of nanovoid is obtained. Calculation results show that: the nucleation and the equilibrium radius of the triple junction nanovoid both depend significantly on the shear stress, the length of the pile-up and the GB structures; the accommodated GB sliding results in the suppression of nanovoid generation, and thereby promotes the ductility deformation behavior in a nanocrystalline material.