Microstructure and mechanical properties of Ti44Al6Nb1Cr2V alloy after gaseous hydrogen charging at 1373–1693 K

The hydrogenation behavior of Ti44Al6Nb1Cr2V (at%) alloy at temperature range of 1373–1693 K and its effect on microstructure and room-temperature mechanical properties were studied systematically in this study. The results show that hydrogen content increases with the increase in temperature, and the maximum hydrogen content is 0.126 wt% at 1693 K. The heat of solution of hydrogen is calculated as 82.9 kJ·mol⁻¹ by curve fitting, indicating that hydrogen absorption in TiAl alloys is endothermic. Hydrogen promotes the lamellar colony size because hydrogen promotes the diffusion of elements. Hydrogen stabilizes B2 phase during hydrogenation resulting in more residual B2 phase in the hydrogenated alloy. The nanohardness and elastic modulus decrease after hydrogenation due to that hydrogen weakens the bonds. The Ti44Al6Nb1Cr2V alloy exhibits higher plasticity and lower flow stress hydrogenation with 0.039 wt% H, and the ultimate compressive strength decreases from 1220 to 1130 MPa, while the fracture strain is enhanced by 26%.