The magnetic behaviour in heterogeneous f.cc. Co10CU90 melt-spun ribbons

摘要

The metastable magnetic alloy ComCugo has been prepared by the conventional melt-spinning technique. The rapid solidification process results in an extended solubility of Co in Cu although some Co particles already have precipitated during quenching. In comparison with conventional ageing methods, Joule heating could also be adopted to fabricate granular Co-Cu alloys with even finer Co particles. The finest size of 4'0nm has been achieved for C010Q190 alloy after annealing with a current I = 4 A for 1 min. Single-domain behaviour results in a value of coercivity in excess of 40-0 kAm" ' for the sample annealed with I= 9-5 A. Below the size of 60 nm, Co particles exhibit superparamagnetic behaviour at room temperature, which has been investigated using a superconducting quantum interference device magnetometer. A unique change in Ms with annealing current or temperature was discovered.