Surface recrystallization of a gamma-TiAl alloy induced by shot peening and subsequent annealing treatments

Fine-grained recrystallization microstructure induced by shot peening and subsequent annealing treatment was achieved in the surface of Ti–48Al–2Cr–2Nb alloy. Annealing treatment at 900 °C for 6–12 h and the lamellar orientation angle of close to 45° are the most favorable conditions for recrystallization. The rotation, dissolution and invasion of the lamellae fragments into the adjacent normal lamellae under the driving force of residual deformation energy with phase boundary bulging mechanism is considered to be the most possible microscopic approach of the recrystallization.