Crystallization of amorphous NiTiCu thin films

The effect of copper additions (1.3 at%) on the crystallization of amorphous nickel-titanium thin films was explored. Using differential scanning calorimetry (DSC), the overall activation energy and crystallization temperatures were found to be similar to pure NiTi. However, in situ transmission electron microscopy (TEM) showed the nucleation and growth behaviors were markedly different. NiTiCu exhibited a lower nucleation rate, suggesting a higher activation energy in comparison to NiTi. The large grains in NiTiCu microstructures are consistent with a lower growth activation energy. These data suggest copper additions create higher interfacial energies. This paper presents experimental measurements that corroborate this mechanism.