Phase formation during ion beam mixing of transition-metal multilayers

Abstract

Abstract Evaporated films of alternating layers of early and late transition metals have been ion beam mixed with inert-gas ions for the study of the phase formation during ion irradiation. The mixing was performed with 500 keV Ar+ and Xe+. In addition, a few co-deposited amorphous films were irradiated, using 200 keV Ne+ and 500 keV Xe+ ions. All the ions fully penetrate the films of approximate thickness 800 Å. The microstructure was investigated by transmission electron microscopy and X-ray diffraction. The homogeneity and composition were checked by Rutherford backscattering spectrometry. The glass-forming ranges of Fe-Zr, Co-Zr, Ni-Zr, Ni-Ti and Ni-Nb were studied as functions of composition, temperature (30–750 K) and ion mass. Besides the amorphous phase, extended terminal solid solutions and, at higher temperatures, some unidentified compounds were observed. The measured glass-forming ranges are discussed in relation to thermodynamic parameters such as the heat of mixing and equilibrium solid solubilities. Furthermore, the ion-beam-mixing amorphization ranges are compared with corresponding ranges obtained by other techniques.