Solubility enhancement and Au-Ni bimetallic alloy formation in immiscible Au/Ni multilayers by ion irradiation

In the present work, we investigated ion beam mixing and grain growth induced in [Au/Ni] × 5 /Si multilayer by 500 keV Xe ion irradiation at different fluence values, using Field Emission Scanning Electron Microscopy (FESEM), X-ray Diffraction (XRD) and Rutherford Backscattering (RBS). Ion-induced grain growth has been evidenced using FESEM analysis and successfully compared to previous experiments and theoretical models. RBS showed total mixing and significant surface sputtering. XRD measurements offered an excellent way to bring light on ion beam mixing kinematics and new phases formation. Thermal spike model calculations combined with the available experimental results in literature of mixing rates enabled us to estimate the diffusivity and examine the validity of inter-diffusion in liquid state. For present work, the atomic diffusivity was estimated to 1.86 × 10-3 cm2/s. The thermal spike model predicted no intermixing for 100 MeV swift heavy Au ion irradiated samples, in good agreement with experimental results.