13th International Conference on Fracture June 16–21, 2013, Beijing, China -5- The correlation between the void lengths at failure and void orientation is not strong. This is different from what was predicted in the work of Hosokawa et al [5]. However, in the previous work isotropic materials were tested where void growth was uniform and linkage occurred by internal necking of the voids. In the magnesium materials tested premature linkage occurs by grain and twin boundary failure. Therefore, the weak relationship between the void fraction and void orientation can be attributed to the fact that the linkage of the holes is not driven solely by plasticity in the magnesium materials tested. Micro XCT has been used to investigate the bulk of the deformed samples. Figure 5 shows a deformed sample with a row of voids perpendicular to the tensile axis with a center to center hole distance of 70 µm. A grain boundary crack was detected by SEM shown in Figure 5a). The reconstructed 3D volume is shown in Figure 5b). Figure 5: a) SEM image b) Reconstructed 3D volume c) Data slice at the back of the sample d) Data slice at the front of the sample. The volume was examined using the Data Viewer software developed by SkyScan which allows the user to view the reconstruction slice by slice. Figure 5c) reveals that a crack has already developed on the side of the sample which cannot be detected by SEM. Figure 5d) shows the depth of the crack that is shown in the SEM image. The results suggest that the failure of the materials tested is very complex and the 3D structure must be accounted for to accurately predict the failure of these materials.
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