Phase stability in pulse electrodeposited nanograined Co and Fe–Ni

Nanograined Co and Fe–Ni films with low levels of defects and impurities were prepared by pulse electrodeposition. The significant reduction in the onset temperature of phase transformation upon heating in nanograined Co and Fe–Ni indicates that these phase transformations are greatly promoted by grain growth, which in turn reduces the thermal stability of the low-temperature-phases ε-Co and α-FeNi. The abnormal stability of the high-temperature phase γ-Co may be attributed to the inhibition of the nanoscale twin boundaries caused by annealing.