In-situ study on the effect of Li concentration on hydrogen microporosity evolution in Al-Li alloys by synchrotron X-ray radiography

The nucleation and growth of hydrogen microporosity during the solidification of Al-Li alloys were in situ observed by synchrotron radiation X-ray radiography, and the effect of initial Li concentration on its evolution kinetics was investigated. The results show that the high Li concentration effectively contributes to the high-temperature nucleation effect of hydrogen microporosity during the solidification of Al-Li alloys, and significantly increases the nucleation and growth rates of hydrogen microporosity. When the initial Li concentration was 2.0 wt%, the nucleation supersaturation of hydrogen microporosity was 1.96, which was 3.5 times higher than that at low Li concentration (1.5 wt%), and the growth rate was up to 2.61 μm/s. In addition, the quantitative results of the final size, morphology, and distribution of the hydrogen microporosity based on 3D X-ray computed tomography (X-CT) showed that high Li concentration not only increased the volume of monolithic hydrogen microporosity, and increased the total number of microporosities, but also increased the degree of irregularity of hydrogen microporosity. The in-situ observation results can provide a new dataset for the establishment and validation of the hydrogen microporosity model of Al-Li alloys.