Abstract
Microtwin sequences in thermoelastic NixAl100-x martensite plates of different size and composition (62·5↬x↬66·0) were investigated by conventional and highresolution electron microscopy. The average twin width increases with increasing twin length and with increasing Ni content. No systematic behaviour of the volume fraction of microtwin variants could be detected, partially due to the numerous stacking irregularities. Such irregularities are attributed to changing boundary conditions during the transformation, leading to multiple needle-shaped microtwins.
