500 kV電子顕微鏡によるアルミニウム疲労クラック近くの組織観察
1970 年 34 巻 7 号 p. 746-752
詳細
1970 年 34 巻 7 号 p. 746-752
Thin-foil specimens of pure aluminium (99.99%) were fatigued at room temperature by an alternative bending apparatus. Structures around fatigue cracks formed in the foils were examined in an electron microscope operated at 500 kV.
As already revealed by transmission electron microscopy at 100 kV, well-defined substructure and strain-concentrated region were observed around a fatigue crack. It was confirmed that voids of 0.1∼1μ in size were formed in the vicinity of fatigue cracks. Voids were also observed in persistent slip bands and in sub-boundaries. Based on the experimental results, the mechanism of fatigue crack propagation due to the coalescences of the voids at the crack tip is suggested. Discussion on the process of void formation and the role of the substructure in fatigue crack propagation is described.
