Analysis of deformation mechanisms in magnesium single crystals using a dedicated four-point bending tester

Abstract

In this study, we explored the deformation mechanisms of Mg single crystals using a combination of scanning electron microscopy and electron backscattered diffraction in conjunction with a dedicated four-point bending tester. We prepared two single-crystal samples, oriented along the 〈11‾20〉 and 〈101‾0〉 directions, to assess the mechanisms of deformation when the initial basal slip was suppressed. In the 〈11‾20〉 sample, the primary {101‾2} twin (T1) was confirmed along the 〈11‾20〉 direction of the sample on the compression side with an increase in bending stress. In the 〈101‾0〉 sample, T1 and the secondary twin (T2) were confirmed to be along the 〈11‾20〉 direction, with an orientation of ±60° with respect to the bending stress direction, and their direction matched with (0001) in T1 and T2. This result implies that crystallographically, the basal slip occurs readily. In addition, the 〈101‾0〉 sample showed the double twin in T1 on the compression side and the tertiary twin along the 〈101‾0〉 direction on the tension side. These results demonstrated that the maximum bending stress and displacement changed significantly under the bend loading because the deformation mechanisms were different for these single crystals. Therefore, the correlation between bending behavior and twin orientation was determined, which would be helpful for optimizing the bending properties of Mg-based materials.

Keywords

• Four-point bending
• Magnesium single crystal
• Twinning
• Basal slip
• Scanning electron microscopy
• Electron backscatter diffraction