Deformation behaviour and 6H-LPSO structure formation at nanoindentation in lamellar high Nb containing TiAl alloy

• Published in: Philosophical magazine letters Vol. 95; no. 2; pp. 85 - 91
• Main Authors: Song, L., Xu, X.J., Peng, C., Wang, Y.L., Liang, Y.F., Shang, S.L., Liu, Z.K., Lin, J.P.
• Format: Journal Article
• Language: English
• Published: Abingdon Taylor & Francis 01.02.2015; Taylor & Francis Ltd
• Subjects: Alloys; Bending; Deformation; Dislocations; Intermetallic compounds; Intermetallics; Lamellar structure; long-period stacking ordered structure; Microstructure; Nanoindentation; Plastic deformation; Strain rate; titanium aluminide; Titanium aluminides; Titanium base alloys; Titanium compounds; Transmission electron microscopy
• ISSN: 0950-0839; 1362-3036
• DOI: 10.1080/09500839.2015.1009515

Microstructure and deformation mechanisms at a nanoindentation in the lamellar colony of high Nb containing TiAl alloy have been studied using the focused ion beam and the transmission electron microscopy. Considerable deformation twins are observed around the nanoindentation, and a strain gradient is generated. A continuous change in the bending angle of the lamellar structure can be derived, and a strain-induced grain refinement process is observed as various active deformations split the γ grains into subgrains. In addition to all possible deformation mechanisms (ordinary dislocation, super-dislocation and deformation twining) activated due to the heavy plastic deformation, a 6-layer hexagonal (6H) long-period stacking ordered structure is identified for the first time near the contact zone and is thought to be closely related to the glide of partial dislocations.