Atomistic study of nanotwins in NiTi shape memory alloys

Atomistic simulations are performed to study the structure and geometrical limit of nanoscale twins in NiTi shape memory alloys. We analyze compound twins as narrow as ∼1 nm, involving a few atomic layers. A novel nanotwinned structure is found, forming through the martensitic transformation of sublattices. We predict the temperatures of phase transformation, which are consistent with experimental measurements. The results provide an atomistic basis for further study of nanometer length scale effects on the martensitic phase transformation and shape memory behavior.