Interface-generated vitrification in the Y-Mo system with a small positive heat of mixing

We report, in this letter, the first observation of vitrification in the Y-Mo system with positive heat of mixing, as a function of the number of interfaces or more precisely the fraction of interfacial atoms, in Y-Mo multilayered films. The thermodynamic driving force is the excess free energy originating from the interfaces, which elevates the initial energetic state of the multilayered films beyond that of the amorphous phase. In addition, the role of a large atomic size mismatch in vitrification is discussed.