Twinning and twin intersections in grains of Ti-42.9Al-4.6Nb-2Cr

A nanoscale observation utilizing the transmission electron microscopy (TEM) device was presented to investigate the hot deformation behavior of beta-solidifying gamma-TiAl alloy (Ti-42.9Al-4.6Nb-2Cr, at.%) with duplex structure, and elucidate twinning and twin intersections in gamma grains. Results showed that twinning is tightly linked to twin intersections in gamma grains. At the initial stage of isothermal compression, faults in two directions with the acute angle of similar to 70 degrees intensively formed in gamma grains. With the proceed of isothermal compression, faults paralleling to each other gradually evolved into twins in the lateral direction, which is helpful to accommodate the atomic plane misfit. And dislocations piled-up advantageously promote longitude twinning in gamma grains. Once faults in all directions evolved into twins, various twin intersections phenomena would be observed in gamma grains. (C) 2021 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.

Automated summary

This study utilized transmission electron microscopy to investigate the hot deformation behavior of a beta-solidifying gamma-TiAl alloy with a duplex structure. It found that twinning is closely linked to twin intersections in gamma grains. As isothermal compression proceeded, faults evolved into twins, with dislocations aiding in promoting twinning in gamma grains.