Abstract: Hydrogenation experiments in porous TC4 alloys are investigated through gas-solid hydrogenated method by using a tubular hydrogen treatment furnace. The influences of relative density, hydrogenation temperature and time on phase composition and microstructure evolution are investigated by means of optical microscope (OP), X-ray diffraction (XRD) and scanning electron microscope (SEM). The result shows that the α phase decreases and β phase increases with the increase of hydrogen content, meanwhile, some δ hydrides are formed. At a certain critical temperature, a certain amount of hydrogen will induce martensite phase transformation, which results in the formation of martensite α'. After hydrogenation, the original equiaxed microstructure in porous TC4 alloy transforms into acicular and lamellar structure. With higher hydrogen content, laminar martensite α' phase is observed when the temperature is higher, while the basket-weave α phase is shown when the temperature is lower. The microstructure of porous TC4 alloy is finer than the titanium alloy powder with the similar hydrogen content.

Key words: Hydride, Hydrogenation, Microstructure, Phase, Porous TC4 alloy