Direct observation of corrosion fatigue cracks in aluminum alloy using ultra-bright synchrotron radiation

Refraction contrast X-ray imaging using synchrotron source with ultra-bright light and highly directional beam is a unique method to diagnose non-destructively cracks or voids formed in materials, providing us in principle completely different information from conventional methods such as absorption contrast X-ray imaging. The authors have applied this imaging technique in SPring-8 to materials fracture study. We have also introduced home-made, in-situ observation facility system of crack formation and propagation in materials and the originally-designed 3D X-ray imaging systems to the experimental Hutch C of BL24XU (Hyogo BL) of SPring-8. Using these 3D X-ray imaging technique, in-situ observations of initiation and propagation of corrosion fatigue crack of Al–10%Mg alloy were conducted. The absorption contrast X-ray images were also obtained for comparison. It is concluded that the X-ray imaging method using ultra-bright synchrotron radiation is very useful for fracture research of materials and 3D X-ray contrast images are much more distinct than the conventional X-ray images to obtain information of the crack initiation and propagation behavior in the alloy.