Effect of severe plastic deformation on the coercivity of Co–Cu alloys

Cast Co–5.6 wt% Cu and Co–13.6 wt% Cu alloys were subjected to severe plastic deformation (SPD) by high-pressure torsion (HPT). The HPT treatment drastically decreases the size of the Co grains (from 20 µm to 100 nm) and the Cu precipitates (from 2 µm to 10 nm). As a result, the coercivity H c of both the alloys radically increases. The saturation magnetization, M s, remains almost unchanged. Thus, SPD of the bulk samples opens the way for drastic increase in the coercivity for the Co-based alloys.