Cobalt rich phase formation in metastable Cu-Co alloys by means of melt spinning

Metastable Co_xCu_100-x alloys with extended cobalt solubility (5 ≤ x ≤ 20), which can not be obtained by equilibrium methods, were prepared by melt spinning. The separation of the cobalt rich phase upon heating was monitored by X-ray diffraction and calorimatric measurements. The volume fraction of cobalt rich particles can not be determined using X-ray diffraction if the cobalt rich particle size is below a critical value. The separation of the cobalt rich phase seems to be a three step process including nucleation, growth, and coarsening. The non-isothermal kinetics of nucleation and growth of the cobalt rich phase were analysed in terms of a modified Kissinger model. The heat release during phase separation is closely related to the amount of cobalt dissolved in the copper matrix.