Three-Dimensional Imaging of Dislocations in a Ti–35mass%Nb Alloy by Electron Tomography

• Main Authors: Kazuhisa Sato, Satoshi Semboshi, Toyohiko J. Konno
• Format: Article
• Language: English
• Published: MDPI AG 2015-04-01
• Series: Materials
• Subjects: electron tomography; dislocations; 3D configurations; Ti–Nb; scanning transmission electron microscopy (STEM)
• Online Access: http://www.mdpi.com/1996-1944/8/4/1924

We have studied three-dimensional (3D) configurations of dislocations in the β phase of a Ti–35mass%Nb alloy by means of single-axis tilt tomography using bright-field scanning transmission electron microscopy (BF-STEM). To visualize dislocations, the hh0 systematic reflections were excited throughout tilt-series acquisition with the maximum tilt angle of 70°. Dislocations in the β grains were clearly reconstructed by the weighted back-projection algorithm. The slip planes of the dislocations were deduced by rotating the reconstructed volumes with the aid of selected area electron diffraction patterns. It was found that BF-STEM images with relatively low contrasts, taken along low-order zone axes, are capable to reproduce and preserve the quality of reconstructed image of dislocations. We also found that tilt angles as low as 40° are practically acceptable to visualize 3D configurations of dislocations, while there exists limitation in resolution due to the existence of a large missing wedge.