Effects of magnetic field on precipitation and growth of ferromagnetic Co particles in Cu-Co single crystals

The effects of magnetic field on the growth of ferromagnetic Co precipitate particles in Cu-2.7 mass%Co alloy single crystals have been examined by the magnetic anisotropy measurement. The (110) disk specimens of the solution-treated Cu-Co alloy were aged at 973 K for 1 similar to 24 h under the magnetic field of 1.25 MA/m parallel to the [001] direction. The magnetic anisotropy was examined by measuring magnetic torque around the (110) plane. Considering the crystal and shape magnetic anisotropies, the torque curves were analyzed theoretically. It is found that the Co particles which precipitate under the magnetic field slightly elongate to the [001] direction parallel to the magnetic field. Furthermore, the torque curves were also sensitive to the coherent-->incoherent shape change of the Co particles. The results can be explained by considering the minimization of the magnetostatic energy of the Co particles.