Formation of Metastable Phases Observed in the Zr-Co-Nb Multilayers upon Ion Beam Irradiation

Six multilayered films with overall compositions of Co10Zr80Nb10, Co10Zr70Nb20, Co20Zr70Nb10, Co30Zr60Nb10, Co20Zr60Nb20and Co10Zr60Nb30were first prepared by alternatively depositing high pure metals onto the NaCl single crystal substrates and then irradiated by 160 keV xenon ions with the doses ranging from 2×1014Xe+/cm2to 9×1015Xe+/cm2. It turns out that several metastable phases, e.g. amorphous phase, were formed in these metallic multilayered films upon irradiation. Meanwhile, some interesting phase transformations were also observed with increasing irradiation doses. Besides, the phase formation and transformation mechanism of non-equilibrium alloy phases are discussed in terms of thermodynamics of solids and atomic collision theory. KEYWORDS: Zr-Co-Nb system, metastable alloys, phase transformation, ion beam irradiation