First-principles study of interfacial energy between alpha-zirconium and zirconium hydride

The interfacial energies among α-Zr, ζ-, γ′-, γ-, and δ-phase zirconium hydride have been calculated via first-principles calculations. Hydrogen biplane configurations of ζ and γ′ are confirmed by binding energy calculations. Based on binding energy calculations and convex hull plots, the ζ phase is not a local stable configuration, and ZrH0.4 is more stable. ζ can be viewed as composed of α and γ′, as well as α∣γ′ interfaces with a 65 mJ/m2 interfacial energy. Thus, ζ is less stable than γ′, assuming no hcp-fct/fcc transformation occurred. Based on the calculated convex hull plots, γ is more stable than δ. The negative interfacial energy between ζ (or γ′) and δ may promote the δ hydride formation.