Magnetoresistance in (Co_xFe_1-x)₂₀Cu₈₀ granular alloys produced by mechanical alloying

The supersaturated solid solution (Co_xFe_1-x)₂₀Cu₈₀ alloys (x = 0-1) were prepared by mechanical alloying. The magnetoresistance (MR), magnetic properties and crystal structure of these alloys were investigated. The MR ratio for the (Co_xFe_1-x)₂₀Cu₈₀ alloys shows a maximum of 6.4% in the Co₂₀Cu₈₀ alloy (x = 1), and decreases with decreasing Co concentration. The b.c.c.-Fe and h.c.p.-Co phases disappear after milling for 50 h, and the f.c.c. phase only is observed. The b.c.c. phase is observed for the alloys with a small MR ratio (x ≤ 0.8), and is the alloy phase of Fe and Co. The b.c.c. phase is not observed for the alloys with a high MR ratio (x ≥ 0.9).