The nanocrystalline Ni-W alloy fabricated by an electrodeposition method has a high-strength and high-bending ductility. However, its fatigue properties are not known yet. Therefore, fatigue tests were carried out to clarify the fatigue properties. Nanocrystalline Ni-W alloy specimens containing 16.9 at% W with about 20 μm in thickness, 200 μm in parallel part length, and 100 μm in width were produced by both UV photolithography and electrodeposition methods. The average grain size was about 6 nm in diameter and the tensile strength was about 2.8 GPa. The fatigue test was conducted at a stress ratio of 0.1 and a frequency of 10 Hz. The fatigue limit and fatigue ratio showed 2.1 GPa and 0.74, respectively. Macroscopic fractured morphology showed no necking and perpendicular fracture for the loading axis. However, microscopic fracture surface showed flat and featureless morphology at near the crack initiation region and it showed striations from the region where the striation spacing became more than about 10 nm. The final unstable fracture surface showed dimples with a diameter of 100~200 nm.
