Abstract
Fatigue deformation studies have been widely undertaken by many investigators, still the fatigue mechanism are not clarified yet. In the present investigation the fatigue deformation and also the fatigue mechanism of annealed polycrystals of pure aluminum (99.99%) have been studied at room temperature and at elevated temperatures of 80°C and 130°C. The deformation behavior of specimens during fatigue was examined by both the replica and the transmission electron microscopy techniques. At the same time the ease of cross slipping at elevated temperatures was taken into consideration.
The results obtained were as follows:
(1) At elevated temperature fatigue, the surface of the specimen is deformed more than at room temperature and the cracks propagate in such a way as to link many micro-cracks which are made of the pores.
(2) Large numbers of dislocation loops were found in the specimen at elevated temperature fatigue. These loops play an important part in forming the cell and they are also closely related to the initiation and the propagation of a crack.
(3) The cell walls are formed by dislocations which are clustered along low index planes, e. g. {100} and {110}. The cell size was larger at elevated temperature (5 to 9μ) than at room temperature (2 to 4μ).
