抄録
Evolution of grain boundary microstructure in electrodeposited nanocrystalline nickel-phosphorus (Ni-P) alloy during high-cycle fatigue test was investigated by using field emission-scanning electron microscopy (FE-SEM)/ electron backscattered diffraction (EBSD) analyses, in order to explain the fatigue properties in bulk nanocrystalline metallic materials. The nanocrystalline Ni-P alloy specimen possessed the average grain size of 45 nm, sharp {001} texture and high fraction of low-Σ coincidence site lattice boundaries. The fatigue limit of nanocrystalline Ni-P alloy was higher than that of microcrystalline Ni. The morphologies of fracture surface were changed in the order brittle fracture mode, fatigue fracture mode and tensile ductile fracture mode. The cyclic stress-induced grain growth was observed at specimen surface. The fractions of low-angle boundaries and Σ3 boundaries m the specimens were decreased by high-cycle fatigue test. The fatigue fracture mechanism was discussed in connection with grain boundary microstructure.
