Deformation of shape memory alloys associated with twinned domain re-configurations

Most of the applications of shape memory alloys (SMAs) imply deformation of martensite; it is therefore one of the fundamental research topics on the shape memory effect. So far, several classifications of the deformation mechanisms have been made as a function of deformation amplitude. However, the deformation details of martensitic SMAs are still not yet satisfactorily understood and these classifications need to be refined, because several incoherencies have been found lately by mechanical testing and transmission electron microscopy (TEM) observations. The present work summarizes some new results on the deformation mechanisms of martensitic NiTi SMAs under tension. As a result, the deformation process of martensite twins as a function of the deformation strain amplitude is refined.