LAUSR

Abstract The stability of binary intermetallic Laves phase YFe 2 and its hydride YFe 2 H x ( x  = 0–5) are studied using first-principles calculation. Accompanied with the analysis of the hydrogen binding energy and the formation enthalpy in various interstitial sites in YFe 2 H x , a transition of the stability from cubic to orthorhombic phase is found when hydrogen concentration increases to 1.5H/f.u. It is found that the hydrogen binding energy is very sensitive to the magnetic property of neighboring atoms. To get a further insight of the transition, we take into account external strains, as well as chemical substitution at Y site. It turns out that the transition point can be tuned by strain and chemical bonding.