Effects of Ni addition on liquid phase separation and giant magnetoresistance of Cu-Co alloys

The effects of Ni addition on the liquid phase separation and giant magnetoresistance (GMR) of Cu-Co alloys were discussed. The results reveal that Ni addition can partially restrain the liquid phase separation of Cu-Co alloys, resulting in a decrease of volume fraction for the Co-rich particles separated from the liquid phase and in refined microstructure. The composition analyses indicate that Ni is dissolved in both the Co-rich and the Cu-rich phases, but Ni content in the Co-rich phase is much higher than that in the Cu matrix. At the same time, Ni addition enhances the solubility between Cu and Co, especially Cu in Co solid solution. Ni alloying into Cu-Co alloys can fully prevent the liquid phase separation during melt spinning, which is very beneficial to improve GMR of Cu-Co alloys.