Microstructure, magnetic and transport properties of melt-spun Cu60(Ni0.8Fe0.2)40 alloys

The effect of annealing on the microstructure, magnetic and transport properties of melt-spun Cu-60(Ni0.8Fe0.2)(40) ribbons is reported. High-resolution analytical electron microscopy on as-spun ribbon shows a granular-like microstructure with the (Ni,Fe)-rich phase, which grows in its size after annealing, embedded in a Cu-rich matrix and a concentration gradient across the interface between the (Ni,Fe)-rich phase and Cu-rich matrix. By analyzing the magnetization curves, we found that the ferromagnetic contribution to the magnetization drastically increases from 11% for as-spun sample to 78% after annealing at 673 K for 240 min, which is clearly correlated to the microstructure modification. The ribbons show complex magnetoresistance behaviors: anisotropic magnetoresistance at low fields and giant magnetoresistance at higher fields. (C) 1998 Elsevier Science B.V. All rights reserved.