A study of the effect of nanostructured surface layers on the fatigue behaviors of a C-2000 superalloy

Fatigue behaviors of a Ni-based C-2000 superalloy subjected to the surface nanocrystallization and hardening (SNH) process were investigated. The influence of the SNH processing condition on the fatigue properties of the material was analyzed. The near-surface structures of the SNH-treated specimens were characterized by means of the scanning-electron microscopy, X-ray diffraction, and transmission-electron microscopy. It is shown that the SNH is an effective method to render the material with the features, such as a nanostructured and work-hardened surface layer as well as compressive residual stresses, which can pronouncedly improve the fatigue strength of the material. However, excessive treatments deteriorate the fatigue properties, and the surface contaminations are considered to be the main reason.