Influences of hydrogenation on room temperature microstructure of Ti6A14V alloy

Hydrogen is usually used as a temporary component to adjust the mechanical properties and the processing abilities of titanium alloys through modifying the microstructure. The paper investigated the microstructure of Ti6Al4V alloy after hydrogenation at solid state by OP, XRD and TEM. It was shown that the content of β phase increases with hydrogen. There are δ titanium hydride (fcc structure, a = 0.444 nm) plates precipitated in the specimens containing hydrogen 0.302wt% and 0.490wt%. Simultaneously, a mass of orthorhombic martensite α″ has been found in the specimens containing hydrogen 0.302wt% and 0. 490wt% as well as δ hydride However, metastable titanium hydride γ (fct structure, c/a = 1.02/1.09) has not been found. This paper presents one eutectoid transformation mechanism from β_H to δ hydride and a based on diffusion transformation theory. The martensite transformation induced by hydrogen has also been discussed.