Effect of ternary Al, Ni additions on hydrogen absorption behaviour of Ti–45Nb alloys

The present study investigates the hydrogen absorption behaviour of a binary Ti–45Nb alloy and the effect of ternary additions of Ni and Al on the pressure–composition–temperature (i.e. p–c–T) behaviour of this alloy. It is found that at a given temperature and partial pressure, the Al-containing alloy has the lowest hydrogen content, followed by the Ni-containing alloy, and that the binary alloy exhibits maximum hydrogen absorption capacity. A comparison of the enthalpy of solution as a function of hydrogen content of the three alloys shows that the enthalpy minimum for the Al-containing alloy occurs at the lowest hydrogen content, followed by that for the binary alloy, and the enthalpy minimum for the Ni-containing alloy occurs at the highest hydrogen content. Enthalpy of solution at infinite dilution of hydrogen shows a linear dependence on the lattice parameter of the host alloys. X-ray analysis of the hydrogen containing samples reveals suppression of the α-phase and the Ti2Ni-phase in the presence of hydrogen.