Precipitation Behavior and Magnetic Properties of Cu-Fe-Co Alloys Containing Nanogranular Ferromagnetic-Element Particles

Abstract

This work investigates the evolution of microstructures and magnetic properties during isothermal annealing of Cu-Fe-Co alloys, using electron microscopy and superconducting quantum interference device (SQUID) magnetometry. Small coherent granular precipitates composed of iron and cobalt formed in the copper matrix in the early stage of precipitation. As annealing proceeded, the precipitates lost coherency to the matrix after reaching a size of 15–20 nm and twin-like structures were consecutively introduced in the particles. The SQUID measurements revealed that the magnetic properties of the specimens correlated with the microstructural evolution. The coercive force initially increased with annealing time but decreased after reaching a peak. Lorentz Microscopy suggested that the initial large increase of magnetization was invoked by a structural transition from fcc to B2 in the precipitates.

Relationship between Microstructure and Magnetic Properties of Nano-Scale Particles Formed in Cu-Ni-(FeCo) Alloys

“…Therefore, this technique is best suited to prepare specimens to investigate the correlation of microstructure and magnetic properties of nano-scale magnetic particles in the coalescent process. Our group has applied this technique to investigate microstructural evolutions and the magnetic properties of Cu-Co [6], Cu-Fe [7], Cu-Fe-Co [8], Cu-Ni-Fe [9] and Cu-Ni-Co [10]. In this work, we investigated nano-granular FeCo particles in Cu-Ni-(FeCo) alloys.…”

Linear arrangements of nano-scale ferromagnetic particles spontaneously formed in a copper-base Cu–Ni–Co alloy

“…Our own team has also conducted investigations of the relationships between microstructures and magnetic properties of magnetic particles formed in various bulk alloys including Cu-Co [15,16], Cu-Ni-Co [16], Cu-Fe [17], Cu-Ni-Fe [17][18][19], and Cu-Fe-Co [20]. The study of homogeneous bulk materials has enabled us to explore in detail the evolution of microstructures on annealing, including the morphology, composition, sizes, shapes and spatial distribution of the particles, and the influence of these parameters on magnetic properties.…”