Abstract
Specimens made of 1441 aluminium-lithium alloy were cycled with constant plastic strain amplitudes and cyclic plastic stress-strain response, and their fatigue life was evaluated. Simultaneously, the changes of the internal structure were studied. In order to assess the inhomogeneity of the material the specimen was made of, the center and the edge of the plate were measured. The material cyclically hardens - only cycling with the highest strain amplitude results in cyclic softening. Cyclic stress-strain curve, Manson-Coffin and derived Wöhler curves were determined. Transmission electron microscopy revealed the character and the internal structure of the slip bands. The cutting and dissolution of δ'-precipitates in the slip bands result in formation of the characteristic ladder-like dislocation structure. Cyclic strain is highly localised and due to strong texture the slip bands easily cross several grains, which negatively influences the fatigue life of the material

Key words
aluminium-lithium alloy, cyclic plasticity, fatigue life, δ'-precipitates, dislocation structures, slip bands

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