Influence of Hydrogenation on Room Temperature Microstructure of Porous TC4 Alloy

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 *a phase decreases and *b phase increases with the increase of hydrogen content, meanwhile, some *d 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 *a'. After hydrogenation, the original equiaxed microstructure in porous TC4 alloy transforms into acicular and lamellar structure. With higher hydrogen content, laminar martensite *a' phase is observed when the temperature is higher, while the basket-weave *a 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.