The recently proposed hypothesis that swift-heavy-ion induced mixing is a consequence of a transient molten state diffusion is tested by studying $230\mathrm{MeV}$ Au ion induced mixing at an $\mathrm{Fe}∕\mathrm{Si}$ interface monitored online by elastic recoil detection analysis. An extensive data analysis has been made to determine the experimental intrinsic diffusivities of Fe in Si, and vice versa. The required size and duration of the transient melt phase have been calculated theoretically from the thermal spike model. The close resemblance of the experimental diffusivities to the liquid state diffusivities reported in the literature is a verification of the hypothesis.

• Received 20 May 2004

DOI:https://doi.org/10.1103/PhysRevB.71.193405