The aim of the present study was to analyse extended defects, related to the twinning, using transmission electron microscopy. Based on these observations, the very early stage of twin nucleation could be attributed to the pole mechanism with deviation proposed by Cohen and Weertman or to the model of Miura, Takamura and Narita, while the twin growth was controlled by the pole mechanism proposed by Venables. High densities of sessile Frank dislocations were observed within the twins at the early stage of deformation, which could affect the growth and the stability of the twins, but also the strength of these twins and their interactions with the gliding dislocations present in the matrix. This experimental evidence was discussed and compared to recent results in order to relate the defects analysis to the macroscopic behaviour of this category of material.

On the Mechanism of Twin Formation in Fe–Mn–C TWIP Steels. H.Idrissi, K.Renard, L.Ryelandt, D.Schryvers, P.J.Jacques: Acta Materialia, 2010, 58[7], 2464-76