Different driving force for metallic glass formation NbNi and NbY systems by ion mixing and solid-state reaction

Abstract

Room temperature 190 keV xenon ion mixing was conducted for the NbNi (heat of formation = −45 kJ/mol) and NbY (heat of formation = +44 kJ/mol multilayered films, which were designed on the basis of free energy calculation. Metallic glasses were obtained not only in the NbNi system but also the NbY system. To discuss the singularity of the observed metallic glass transition, Miedema's model was employed to construct the corresponding Gibbs-free-energy diagrams, including the free energy curves of amorphous phase and the multilayered films with various fractions of interfacial atoms. The constructed diagram can give a qualitative and reasonable interpretation to the ion mixing results. More interestingly, the interface concept was also applicable to solid-state reaction and thermal annealing of the multilayered films designed under similar considerations and indeed resulted in the formation of glasses in the Nb-Y system, which has long been recognized as a non-glass system.