Nano-structure of Bulk Nano-granular Material in Cu/Co System

Abstract

Nano-granulation process of Cu/Co system is investigated on the route of bulk mechanical alloying. Using the bulk mechanical alloying, the super-satu rated solid solution of Cu-20mol%Co has been prepared. Through the further h eat treatment, the Co nano-precipitated from the super-saturated solid solut ion in the copper matrix, resulting in appearance of the giant magneto-resis tance. In the present study, the nano-precipitation of Co and the Co-particu late size is investigated by XRD, VSM and TEM. The relationship between the magneto-resistance ratio and the nano-precipitation process of Co is investi gated. This relation depends on both the nucleation rate of Co-cluster preci pitate and the growth rate of Co-cluster. The change of the magneto-resistan ce ratio with the Co-cluster size is also obtained: Co precipitate size mus t be 1-3 nm to attain higher magneto-resistance ratio than 10%.