Characterization of Fatigue Fracture in Ni-20 Pct Cr Alloys Using White Light Interference Microscopy and Scanning Probe Microscopy

摘要

Nanostructured and ultra–fine-grained metals and alloys are becoming of engineering interest. However, little is known about the influence of grain refinement on fatigue crack behavior. In this study, fatigue crack growth behavior and the key microstructural features controlling the fatigue fracture in nanocrystalline and ultra–fine-grain nickel alloys, processed using different techniques, were investigated. White light interference microscopy as well as the combination of atomic force microscopy (AFM) and ultrasonic force microscopy (UFM) were used to characterize the fractured surfaces of the metals. The role of grain size on the fatigue crack growth resistance and the effect of fracture surface roughness on the crack growth rate were evaluated. The combination of AFM and UFM is presented as a complementary tool to scanning electron microscopy in the fractography of metals.