Studying hydrogen redistribution at microstructure length scales via lattice swelling measurements

Hydrogen (H) fuel will play an important role in decarbonising aviation. However, H ingress in metals is known to dramatically degrade mechanical properties due to hydrogen embrittlement (HE). Despite decades of research, the influence of microstructure remains little understood, as models at this scale are still in their infancy. This proposed research aims to fill this knowledge gap by employing Laue diffraction for grain orientation mapping and strain measurements of stressed metallic polycrystals with and without H to quantify microstructure-driven H-redistribution by measuring H-induced lattice swelling directly, and via an Eigenstrain modelling methodology. From this, we will identify key microstructure characteristics affecting HE and ultimately validate high-fidelity models we are developing to predict component life. We aim to deduce the effects of elastic anisotropy and grain morphology on H localisation (and hence HE) at the µm-scale.