High-voltage electron-microscopic observation of cyclic slip behavior around a fatigue crack tip in an iron alloy

The cyclic slip behavior around a fatigue crack tip originally located inside a bulk Fe–Si alloy was successfully observed by a high-voltage electron microscope in combination with a novel specimen preparation method. The method, by taking advantages of ion milling and focused ion beam techniques, ensures that the original shape of the crack tip is preserved without introducing additional slips. The observation confirms that the slip bands emitted from the fatigue crack tip are bounded by a labyrinth-like wall structure.