We have presented the results of a crystallization study on NiTi shape memory thin films in which amorphous films were annealed by scanning a laser across the surface of the film. Our results show that under the correct conditions of laser power density and scanning speed, it is indeed possible to crystallize the films. Moreover, X-ray diffraction clearly shows the formation of martensite in the crystallized sections of the film. The temperature profiles induced by the laser beam were calculated using a three-dimensional finite element model. The model takes into account the crystallization kinetics of amorphous NiTi and allows prediction of the size of the crystallized regions as a function of laser annealing parameters if the reflectivity of the NiTi surface is known. Our results further show that it is critical to minimize oxide growth during the laser-annealing process for good control of the process.
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