Photoelectron microscopy of plastic zone around a fatigue crack
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The photoelectron emission from a metal is enhanced by fatigue cycling. This increase, which is often referred to as exoelectron emission, has been observed directly in a photoelectron microscope. The increase of emission results primarily from the rupturing of the thin surface oxide, thereby revealing a fresh metal surface of lower work function. During the propagation of a fatigue crack there are two sources of exoelectrons. 1) The crack itself, which emits very strongly and is easily identified. 2) The deformation generated in the nearby material,i.e. the plastic zone. In addition, the active portion of the plastic zone at the crack tip may be distinguished from the relatively inactive wake of deformed material.
KeywordsFatigue Metallurgical Transaction Fatigue Crack Plastic Zone Fatigue Cycle
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