LAUSR

Since the introduction of high‐strength aluminum alloys understanding their fatigue behavior is of high interest for the structural integrity of engineering components, in this context, the alloy EN AW‐2618A gains its high strength from both nanometer size precipitates and micrometer size primary phases. The latter phases are often identified as crack initiation sites. In this study, it uses a combination of synchrotron and laboratory‐based X‐ray computed tomography to image and quantify such primary phases and the fatigue cracks appearing in interrupted tests. Based on the gray‐level differences in the synchrotron X‐ray computed tomography scans, this study is able to distinguish low‐ and high‐absorbing particles. The dominant (volume fraction >99%) high absorbing primary phase can be quantified in good agreement with results of Thermo‐Calc calculations. To image the fatigue crack, laboratory X‐ray computed tomography scans are performed at different tensile loads to open the crack. The results show that with an appropriate crack opening tensile load, the fatigue crack morphology can be reliably revealed. Based on these results, the influence of the primary phases on the fatigue crack initiation and propagation are discussed.