Guiding postprocessing of LPBF Ti2AlNb parts by 4D imaging AM defects during high temperature fatigue

Ti2AlNb alloy is a light weight, high performance, high temperature material with a density (~5.3-5.4 g/cm³) just 60% that of nickel-based superalloy (8.0-9.2g/cm3). The advent and rapid development of AM enables the direct fabrication of Ti2AlNb alloy into complex geometry parts. However, LPBF tends to result in defects whose presence are detrimental to fatigue performance. Therefore, LPBF Ti2AlNb is generally post-processed by hot isostatic pressing (HIP) or heat treatment (HT) to reduce defects, however, we find that these treatments are not always effective and their parameters need to be optimised . Here, by using synchrotron X-ray 𝜇CT, we aim to evaluate the efficacy of different treatments and their influence on fatigue of LPBF Ti2AlNb. Our results will be of significant benefits for industrial applications. To our knowledge, this will be the first experiment, where the evolution of defects in LPBF Ti2AlNb is observed in-situ 3D during very high temperature fatigue testing.