Relationship between the microstructure and the magnetic properties of nano-scale magnetic particles formed in a Cu-10 at% Ni-5 at% Co alloy

Cu-10 at% Ni-5 at% Co specimens containing nano-scale magnetic particles were investigated with respect to the relationship between the microstructure and the magnetic properties, by using a transmission electron microscope (TEM), a SQUID magnetometer and a magnetic thermobalance. The present TEM observations revealed that small magnetic precipitates were formed in a copper matrix in a specific manner that has never been reported in conventional precipitation alloys consisting of non-magnetic elements. The SQUID measurements indicated that a specimen annealed for a short period had a large coercive force, although the force decreased for longer annealing treatments. The magnetic thermogravity scan in the temperature range of 300-1223 K showed that the alloy specimen had a paramagnetic state between two ferromagnetic regions.