Thermal stability of solid solutions formed by ultrasonic milling of Cu-Co and Cu-Fe powder mixtures

Abstract

The structure and magnetic properties of coarse-grained copper-cobalt and copper-iron powder-mixtures produced by the ultrasonic milling and annealed at 600 or 800 ° C have been studied, by using the X-ray diffraction and magnetometry methods. The treatment of the mixtures in an ultrasonic ball mill is shown to result in the mutual dissolution ofmetals and the solid solution formation, as well as in a considerably finer mixture structure. The following annealing of those powder mixtures at 600 ° C did not change their phase compositions, but substantially affected the size of coherently scattering domains. In the both cases, the latter grew by almost an order of magnitude in agreement with the Lifshitz-Slyosov-Wagner theory. The annealing of the specimens at 800 ° C resulted in the absolute decomposition of supersaturated solid solutions formed under the ultrasonic treatment.