High energy product of Sm$_{2}$Co$_{7}$/FeCo nanocomposites prepared by severe plastic deformation

Nanocomposite magnets, consisting of exchange coupled hard magnetic and soft magnetic phases exhibit enhanced remanent magnetization and therefore high energy product \textit{(BH)}$_{ max}$. In addition to the high performance, nanocomposites magnets are of commercial interest because the alloys require less expensive rare-earth elements. Here, we report Sm$_{2}$Co$_{7 }$+ x wt {\%} FeCo (x = 0 to 50) nanocomposites prepared by high energy ball-milling and subsequent heat treatments. The evolution of structure and magnetic properties with soft phase fraction was systematically studied. Effect of the soft phase composition Fe$_{100-X}$ Co$_{X}$ ( x = 20, 35 and 50) was also investigated. Microstructural studies by energy filter transmission electron microscopy revealed a homogeneous distribution of -Fe phase in the matrix of hard magnetic Sm-Co phase with grain size less than 20 nm after severe plastic deformation. Enhanced remanence and \textit{(BH)} $_{max}$ (up to 17 MGOe) in the nanocomposites with 40 {\%} of the soft phase are obtained.