Amorphization was achieved by room-temperature 200 keV xenon ion mixing in Zr-Mo multilayered films. In addition, two new Mo-based metastable crystalline phases were obtained, which were of FCC and HCP structures, respectively. A Gibbs free-energy diagram that concerns the free-energy curves of the amorphous phase and the terminal solid solutions was constructed to give related thermodynamic explanations to the observations.