Investigation on the microstructures and hydrogen embrittlement mechanism of hydrogenated Ti6A14V

The microstructure of Ti6A14V alloy after hydrogenation has been investigated by XRD and TEM. It is shown that there are δ titanium hydride (fcc structure, a = 0.444 nm) plates precipitated in the specimens containing 0.302wt% and 0.490wt% hydrogen. Simultaneously, mass tetragonal martensite α″ has been found in the specimens as well as δ hydride. One eutectoid transformation mechanism from β_H to δ hydride and α-Ti is presented, based on diffusion transformation theory. The martensite transformation induced by hydrogen has also been discussed. Hydrogen-induced embrittlement did not appear until the hydrogen content exceeded 0.102wt%. δ titanium hydride and martensite a has the leading effects of hydrogen embrittlement of Ti6A14V alloy at room temperature, and δ hydride plates distributed along grain boundaries make for the germination and propagation of crack, while the tetragonal martensite α″ has positive effect on the propagation of crack. As a result, these two phases jointly caused the hydrogen embrittlement of.