Transmission Electron Microscopy Investigations of Fatigued Copper Single Crystals: Experimental Aspects

摘要

Dislocation configurations in slices of material taken ahead of the fatigue crack tip in copper single crystals were observed through transmission electron microscopy. These observations revealed: (a) a distinct transition in configuration as a region within approximately 250 microns of the crack tip was approached and (b) a reduction in dislocation cell size with decreasing distance from the crack tip similar in form to cell-size-vs-fatigue-stress-increase curves. These observations lend support to the concept of a distinct 'plastic zone' in the vicinity of the fatigue crack tip, with associated blunting-type crack propagation mechanisms. (Author)