Preparation of FeCo-, FeNi- and NiCo-alloy coated cenosphere composites by heterogeneous precipitation

Precursors of binary alloy (Fe1/2Co1/2, Fe1/2Ni1/2, Ni1/2Co1/2, hereinafter referred to as FeCo, FeNi, NiCo) coated cenospheres were prepared by heterogeneous precipitation under optimized conditions. Magnetic binary alloy coated cenosphere composites with core-shell structure were subsequently obtained by thermal reduction of the as-prepared precursors at 700 degrees C for 2 h under H-2/N-2 atmosphere. The results showed that the alloy coatings were uniform and the binary alloy coated cenosphere composites basically retained the spherical morphology, suggesting that the thickness of the alloy coating could be adjusted to fabricate core-shell composites with multilayer structures. The composites exhibited higher coercivity than the pure alloy powders, and could therefore be used for high-performance functional materials and devices. (C) 2011 Chinese Society of Particuology and Institute of Process Engineering, Chinese Academy of Sciences. Published by Elsevier B.V. All rights reserved.