Unstable crack extension in high strength aluminium alloys

摘要: Abstract Unstable fracture has been observed in high strength aluminium alloys, associated with a change mode from transgranular to intergranular after short, stable crack extension. The is accompanied by drop toughness and sudden extension rapid until arrest occurs. Fast reinitiated when the applied stress intesity factor raised level of quasi-static toughness. degree instability, as measured length fast extension, depends on prior heat treatment test temperature. It believed that may be triggered microfracture brittle second phase particles. A simple model used relate microstructural features surface.