The unique strain reversible superelastic and shape memory behaviour of NiTi alloy is due to martensitic transformation between the cubic austenite and monoclinic martensite phase. As the austenite phase transforms to martensite during cooling or mechanical loading, the austenitic grains become filled with blocks of martensite variants restricted by lattice correspondence and requirement for strain compatibility at newly created interfaces. The arrangement of martensite variants in grains depend on the stress at which the martensitic transformation occurs. When martensitic NiTi is further deformed, these martensite variants rearrange and deform plastically which leads to yeat another martensite variant microstructure.  
In this work we attempt to reconstruct the martensite variant microstructures evolving during tensile deformation of nanocrystalline martensitic NiTi wire by ex-situ TEM using two different approaches. The first, manual method consists in tilting the selected grain into specific low index zone, analysis of the composite diffraction pattern and dark field imaging. The second method employs automatic orientation mapping by ASTAR allowing for mapping nanoscale martensite variant microstructures in general crystallographic orientation with excellent spatial resolution. The reconstruction of martensite variant microstructure by application of both methods is presented and the pros and cons of both methods are discussed.