Individually, alloying and ion irradiation are two avenues for modifying the chemical and phase structure at solid-state interfaces. Both can lead to the phenomena of alloying, intermixing, and, when combined, radiation-induced elemental redistribution. Thus, understanding how each independently influences the structure of interfaces provides insight into the chemical morphologies at the interface, the possible formation of secondary phases, and the basic mechanisms necessary for understanding alloying. Within the analytical framework provided by electron microscopy, we study changes in structure and chemistry in connection with the formation of composite layered interfaces following alloying and ion irradiation at metal-oxide interfaces. In particular, the chemical evolutions of as-deposited Fe/Cr and irradiated Fe thin films on \(\hbox {TiO}_{2}\) are characterized to reveal structural and chemical changes associated with physical interactions induced by either alloying or irradiation. The results of the study conclude by comparing the effects of alloying with radiation-induced intermixing. We find that the extent of Fe intermixing into the \(\hbox {TiO}_{2}\) substrate is similar for both irradiated and alloyed films, indicating that both can lead to the formation of similar complex nanoscale morphologies at the interface. Our results highlight the complex and competing phenomena that dictate the structure and chemistry at these interfaces.