New approach to achieve high strength powder metallurgy Ti-6Al-4V alloy through a simplified hydrogenation-dehydrogenation treatment

Abstract A simplified hydrogenation-dehydrogenation approach is demonstrated to achieve high strength powder metallurgy Ti-6Al-4V alloy by introducing 0.90  wt. % hydrogen in the green compact, without the help of hydrogen flow. The refined cross-linked network microstructure, where ultra-fine β phase dispersed in between refined α phase, produces a high tensile strength of ∼1062 MPa. A fixed orientation relationship was determined between these refined α phase and ultrafine β phase, which predicts a coherent interface makes the alloy stronger and showing transgranular and ductile fracture, avoiding intergranular fracture along the β grain boundary as in vacuum sintered sample. The influence of hydrogen content on mechanical properties and microstructures is also investigated in detail. The critical hydrogen content of 0.36  wt. % was revealed for presenting the beneficial effect of hydrogen.