Microstructure of Ti–6Al–4V processed by hydrogenation

Precipitation of α2 (Ti3Al) and β phases in the form of platelet or spherical particle in the α matrix of Ti–6Al–4V was observed after hydrogenation/dehydrogenation treatment at 600 °C. The crystallographic orientation relationship of α and α2 was determined to be 〈12¯10〉α∥〈12¯10〉α2 and {0 0 0 1}α∥{0 0 0 1}α2. The nanoscale β phase precipitated in the α matrix was also observed, with their orientation relationships being {0 0 0 1}α∥{1 1 0}β and 〈112¯0〉α∥〈111〉β. The formation of α2 and β phases can be attributed to the disproportionation effect.