Environmentally assisted cracking of a single crystal nickel-based superalloy

Single crystal material, of CMSX-4® alloy composition, was cast and secondary orientation controlled at the machining stage, to produce c-ring cross-section tubes with known crystallographic orientations. The were coated NaCl before being subject loading up 700MPa heated for durations 2 hrs 550°C in flowing environments containing air SO2.No cracking observed short term tests that run absence either NaCl, or SO2, indicating a symbiotic interaction is required initiate cracking. Experiments confirm presence oxygen, chlorine sulphur crack tips, formed along {001} planes, however, they distributed discretely, several oxide sulphide phases observed.In this work, we image, analyse identify during corrosion superalloy hypothesise on complex chemical interactions take place initiation.