ROLE OF INTERFACE IN ION MIXING INDUCED AMORPHIZATION IN THE AG-MO SYSTEM WITH VERY POSITIVE HEAT OF FORMATION

A free energy diagram of the Ag-Mo system with a very positive heat of formation of +57 kJ/mol was constructed, with special consideration t o the interfacial free energy in the multilayered films for ion mixing . It was found that amorphization was possible to achieve within two s eparate composition ranges toward Ag and Mo ends, respectively, if 12 layers, or about 13% of the interfacial atoms were included in the fil ms. Accordingly, ion mixing of the Ag-Mo multilayered films was conduc ted at liquid nitrogen temperature by 190 keV xenon ions and the forma tion of amorphous phases was in good agreement with the calculation. B esides, a new metastable fcc phase was formed and, more interestingly, it transformed into an amorphous state upon aging, which can also be interpreted by a related free energy calculation. (C) 1995 American In stitute of Physics.