Occurrence of Single and Double Slip Crossover Bands in Fatigued Alloys C460 and C22

Aluminium lithium alloy C460 and nickel chromium alloy C22 are used extensively in the aerospace industry for various aircraft components. In this study, fine and coarse -grained specimens of these alloys were subjected to fatigue testing in air and at room temperature in a servo-hydraulic testing machine to study fatigue behavior and the microstructures developed by cyclically deforming the specimens in a series of stress-strain hysteresis loops. Microstructural characterization revealed the development of single and double slip crossover bands within grains. Further, it was found that double slips crossover band density increased with the number of cycles to failure, with double slip crossover bands being more pronounced in C22 than in C460. Double slip crossover bands in C22 were readily observed by scanning electron microscopy (SEM), whereas, for C460 the clear observation of double slip crossover bands required transmission electron microscopy (TEM).