Fatigue Properties in Electrodeposited Nanocrystalline Ni-W Alloy

Abstract

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 mm in thickness, 200 mm in parallel part length, and 100 mm 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.

Fabrication of Ni–W Microgears Using LIGA Process

“…In this study, the Ni-W electrodeposited alloy (3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14) developed by Yamasaki and others, which showed high strength and ductility, has been applied to the LIGA process using synchrotron radiation to fabricate high-precision microgears with high durability. Ni-W electrodeposited alloys have nanocrystalline/amorphous composite structures with high plastic deformability despite their high strength.…”