Effect of the interchangeability of Ti and Nb on the crystal structure and hydrogen storage properties of Ti x Nb 80-x Al 10 Cr 10 (x=30, 40, and 50) multicomponent alloys

This work investigated the influence of Ti and Nb interchangeability on the hydrogen sorption properties of the Ti x Nb 80-x Al 10 Cr 10 (x = 30, 40, and 50) multicomponent system. The CALPHAD method was successfully employed to design body-centered cubic (BCC) solid solutions. These alloys absorb hydrogen at room temperature, achieving a hydrogen-to-metal ratio of about 1.7. Pressure-Composition-Temperature diagram measurements demonstrated that increasing Ti content at the expense of Nb led to increased stability of the metal hydrides. DFT calculations of the pure elements and binary hydrides of the Ti-Nb-Al-Cr system were carried out, and the lattice parameters of the BCC alloy and FCC hydride and the enthalpy of hydride formation were estimated by applying an ideal mixing rule. The calculated and experimental results showed satisfactory agreement, indicating that the theoretical approach can be used to estimate the structural and thermodynamic parameters of alloys and hydrides of the Ti x Nb 80-x Al 10 Cr 10 system.