LIQUID-PHASE SEPARATION IN MELT-SPUN CU70CO30 RIBBON

Due to the large heat of mixing in the Cu-Co system, liquid phase sepa ration is inevitable in Cu70Co30 ribbons during the course of the quen ching process. The resulting large Go-rich particles exhibit either el ongated or roughly spherical morphology with a distinct Gu-rich shell. The large Go-rich particles are about 100-300 nm and the shell is abo ut 15-40 nm wide. On annealing, diffusion of Gu and Co through the she ll region results in a broadening and eventual disappearance of the sh ell region. A maximum magnetoresistance of 22% results after annealing at 723 K for 1 h, and more investigations are necessary to clarify th e contribution of these large Go-rich particles to the observed magnet oresistance.