Martensite nucleation on dislocations in Cu-Al-Ni shape memory alloys

In the present work, the martensite nucleation on dislocations has been observed. Cu-Al-Ni shape memory alloys have been superelastic cycled inside the transmission electron microscope. The in situ experiences show that the dislocations in beta phase can be a nucleation site for gamma(')(3) and beta(')(3) martensites, which at the same time have been characterized by electron diffraction. The martensite plates can nucleate on the dislocations when the stress is applied and retransform to the beta(L21) phase when the sample is unloaded. The results are discussed in terms of the atomic configuration of the dislocation core, which facilitates the martensite nucleation. (c) 2007 American Institute of Physics.