Molecular dynamics simulation was performed to investigate the influence of twin boundary （TB） spacing on crack propaga- tion of AI. This study reveals the orientation of initial crack may affect the mechanism of cr...Molecular dynamics simulation was performed to investigate the influence of twin boundary （TB） spacing on crack propaga- tion of AI. This study reveals the orientation of initial crack may affect the mechanism of crack growth obviously. TB strengthens A1 when the crack orientation is parallel with TB because of the hinderance of TB to the emission of the disloca- tions. The results indicate that there is an optimal TB spacing for mechanical properties of the A1, exhibiting reverse HP （Hall-Petch） and HP effect when the TB spacing is near the critical TB spacing. Furthermore, we find that there is a yield strength hardening effect in nanotwinned A1 when the crack orientation is perpendicular to the TB, and the Young＇s modulus is smaller in the nanotwinned A1 than that of twin free A1. The studies also demonstrate that this distinctive deformation behavior is related to nucleation of dislocations and the repulsive force of TB to the dislocations and crack propagation, as well as the distance between the crack tip and the TB.展开更多
基金supported by the National Natural Science Foundation of China(Grant No.10902083)the Program for New Century Excellent Talents in University(Grant No.NCET-12-1046)the Program for New Scientific and Technological Star of Shaanxi Province(Grant No.2012KJXX-39)
文摘Molecular dynamics simulation was performed to investigate the influence of twin boundary （TB） spacing on crack propaga- tion of AI. This study reveals the orientation of initial crack may affect the mechanism of crack growth obviously. TB strengthens A1 when the crack orientation is parallel with TB because of the hinderance of TB to the emission of the disloca- tions. The results indicate that there is an optimal TB spacing for mechanical properties of the A1, exhibiting reverse HP （Hall-Petch） and HP effect when the TB spacing is near the critical TB spacing. Furthermore, we find that there is a yield strength hardening effect in nanotwinned A1 when the crack orientation is perpendicular to the TB, and the Young＇s modulus is smaller in the nanotwinned A1 than that of twin free A1. The studies also demonstrate that this distinctive deformation behavior is related to nucleation of dislocations and the repulsive force of TB to the dislocations and crack propagation, as well as the distance between the crack tip and the TB.
