Twinning-induced dislocation and coordinated deformation behavior of a high-Nb TiAl alloy during high-cycle fatigue

The deformation mechanism responsible for the high-cycle rotating bending fatigue of a high-Nb TiAl alloy was investigated. Fatigue deformation in the gamma phase was dominated by superlattice dislocations [0 1 1] and twin-ning. Dislocations 11 0 in the B2 phase can be induced by twins in the adjacent gamma phase, which has a low stacking fault energy owing to the high Nb content. Stress transfer between two adjacent phases can be accomplished through atomic rearrangement of the interface by twinning. The local stresses were accommodated by the continuous dislocation slip of the B2 phase, deformation twins, and twin intersections in the gamma phase.

Automated summary

The deformation mechanism responsible for the high-cycle rotating bending fatigue of a high-Nb TiAl alloy was studied. Superlattice dislocations [0 1 1] and twinning dominated the fatigue deformation in the gamma phase. Dislocations 11 0 in the B2 phase were induced by twins in the adjacent gamma phase due to the low stacking fault energy caused by the high Nb content. Stress transfer between adjacent phases was achieved through atomic rearrangement of the interface by twinning. Local stresses were accommodated by continuous dislocation slip in the B2 phase, deformation twins, and twin intersections in the gamma phase.