In-situ SEM study of fatigue crack initiation and propagation behavior in 2524 aluminum alloy

With the help of in-situ scanning electron microscopy(SEM) fatigue test, the fatigue crack initiation and propagation behavior in a high strength 2524 aluminum alloy have been investigated using a non-notch sample at room temperature. The results show that fatigue cracks in 2524 alloy nucleate on inclusion particles or the interface between inclusion particles and matrix material. The main crack propagation is found to propagate along either slip bands in a shearing mechanism or along the direction of micro-crack ahead of crack tip in a crack-linking mechanism. The micro-crack propagation direction and rate can be affected by the grain boundary(GB). [Display omitted] •Inclusion particles of 7–8μm diameter in AA2524 alloy are most likely to initiate cracks, whilst particles smaller than 2μm do not•Shearing and crack-linking are the key crack growth mechanisms in this alloy.•Fatigue cracks were found to deflect at grain boundaries.