Microstructure and deformation mechanisms in nanocrystalline Ni–Fe. Part I. Microstructure

We investigate various microstructural features of nanocrystalline electrodeposited Ni–Fe with a nominal iron content of 50% and compare them with the well-known nanocrystalline Ni system. In-depth electron microscopy analysis reveals the existence of large strain variations in the grain interior. Three-dimensional atom probe studies demonstrate no significant segregation to grain boundaries. However, significant deviations from a perfect chemically disordered system are found, which can be related to compositional variations of 5% over length scales of only a few nanometres. Finally, X-ray diffraction measurements suggest higher dislocation and twin density in Ni–Fe compared to Ni