The project A8 investigates with transmission electron microscopy technique microstructural aspects of thermal and stress-induced martensitic transformations in NiTi shape memory alloys. Both conventional TEM (microstructures, phase analysis, chemical analysis) and in-situ TEM investigations (heating/cooling and straining) will be carried out. Interesting experimental results of the precipitation and growth of Ni-rich particles in the NiTi system will be modeled with the phase-field method.