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

摘要

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-fineβphase dispersed in between refinedαphase, produces a high tensile strength of ～1062?MPa. A fixed orientation relationship was determined between these refinedαphase and ultrafineβphase, which predicts a coherent interface makes the alloy stronger and showing transgranular and ductile fracture, avoiding intergranular fracture along theβgrain 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.