The structure and phase transformations of thin Ni-Ti shape memory alloy films grown by molecular beam epitaxy are investigated for compositions from 43 to 56 at. % Ti. Despite the substrate constraint, temperature dependent x-ray diffraction and resistivity measurements reveal reversible, martensitic phase transformations. The results suggest that these occur by an in-plane shear which does not disturb the lattice coherence at interfaces.
Bibliographical noteFunding Information:
We thank J. L. Hall, R. Liptak, and L. Feigl for fruitful discussions. This work was funded by ARO-MURI Grant No. W911NF-07-1-0410. The MRL Central Facilities are supported by the MRSEC Program of the NSF; a member of the NSF-funded Materials Research Facilities Network.