an edm wire having an outer coating of gamma phase brass with an overlayer of continuous unalloyed zinc or ductile epsilon phase brass entrapping the gamma phase and a process for manufacturing the edm wire is provided . a second process for synthesizing a ductile epsilon phase brass coating on the aforementioned and other substrates is also provided . the first process includes coating a copper bearing metallic core with zinc . the zinc coating is then converted to gamma phase brass via a diffusion anneal and subsequently re - coated with zinc prior to being cold drawn to its finish diameter .