Influence of the milling conditions on the magnetoresistive properties of a Cu80(Fe0.7Co0.3)20 granular alloy elaborated by mechanical alloying

Abstract High-energy ball milling was used to prepare a magnetoresistive granular alloy composed of Fe70Co30 magnetic clusters dispersed in a Cu matrix. Two milling processes were tested. The first process consists of milling a mixture of pure Cu, Fe and Co powders. The second process consists of milling a mixture of Cu and Fe70Co30 powders. The first milling process leads to the formation of a Cu–Fe–Co solid solution after 20 h of milling. This solid solution was subjected to annealing treatments to obtain a granular structure. After annealing at 415 °C for 1 h, the magnetoresistance reaches its optimum (16% at 5 K). With the second process, the Fe70Co30 phase is directly dispersed in the Cu matrix. After 20 h of milling, the structure of the powder is similar to that obtained from the first process followed by annealing at 415 °C, but the magnetoresistance is lower (5% at 5 K).