Co/Cr alloys are among the most prominent materials for ultra-high density longitudinal magnetic recording media. The recording and magnetic properties of the materials are related to their microstructure. It has been found that compositional segregation (CS) of the Co phase at the grain boundaries, and physical separation of Co/Cr phases are effective in producing low noise media due to low intergranular exchange coupling. A series of Co/Cr alloy magnetic thin films were prepared by DC sputtering and studied using high-resolution transmission electron microscopy (HRTEM) coupled with energy dispersive x-ray spectroscopy (EDS). CoxCryPzPtw/Cr alloy thin films were deposited on circumferentially textured Ni-P/Al substrate. This substrate geometry was used to get better magnetic properties without substrate bias. A Hitachi HF-2000 field emission TEM was used for imaging and to provide a 1 nm beam for high spatial resolution EDS analysis.