Hydrides in α-Ti: Characterization and effect of applied external stresses

The hydrides precipitated in commercially pure titanium, produced by cathodic hydrogenation followed by a thermal diffusion treatment, have been characterized using optical and electron microscopy. δ and γ-hydrides have been observed in specimens with low hydrogen concentrations (⩽500 wppm). Hydrides with {011¯0} habit plane were the most abundant ones. Hydrides with {0 0 0 1} and {101¯7} habit planes, both with the same matrix–hydride crystallographic relationship, have also been recognized. The {101¯2} habit plane was confirmed by transmission electron microscopy with a {01¯11}//{001} and 〈21¯1¯0〉//〈11¯0〉 orientation relationship. The distribution of the orientation of the hydride platelets was studied with increasing levels of constant load applied during a cooling process. The relative frequency of precipitated hydrides in planes perpendicular to the tensile axis was increased and this was more remarkable when the orthogonal plane corresponds to a prismatic plane.