As the use of metals in hydrogen-intensive environments becomes increasingly important for future energy solutions, the need to understand microstructure–hydrogen interactions also becomes more critical. Titanium alloys are a key class of structural materials used for their high specific strength and good corrosion resistance, but they can experience hydrogen embrittlement due to the formation of hydrides. This phase transformation involves both a volume expansion, leading to localised internal stresses, and to the presence of the weaker hydride phase in the microstructure, creating pathways for cracking to occur prematurely. Alongside this, titanium alloys display a variety of complex microstructures that are readily adapted by processing routes, so that understanding the microstructural factors that influence hydride formation is of significant interest.

Previous studies have indicated that hydride formation at α/β phase boundaries is sensitive to the surrounding microstructural length scales. Hydrogen transport is also sensitive to crystallographic orientation and microstructural features. Here, we capture large areas of microstructure using scanning electron microscopy with in situ electrolytic charging. This enabled time-resolved observations of nucleation and growth processes in a dilute α+β alloy with a refined, equiaxed microstructure. We consider local microstructure and texture in determining the factors that influence hydride nucleation locations and, with continued charging, observe variations in growth behaviours occurring at the grain scale and across large regions of microstructure. Our analysis clarifies the roles of morphology, phase percolation and crystallography on localised hydride formation within α+β titanium alloys.