Magnetic softening of Co doped α-Fe16N2 containing residual Fe-Co alloy prepared in low temperature nitridation

Preparation and magnetic properties were investigated on the Co doped alpha ''-Fe16N2 obtained in low temperature nitridation of bcc Fe1-xCox alloys to change its magnetic coercivity. The alloys were prepared by the reduction of (Fe1-xCox)(3)O-4 obtained by hydrolysis of iron and cobalt acetylacetonate mixture in benzyl alcohol. Fine powder of the pure spinel-type (Fe1-xCox)(3)O-4 was obtained in x = 0-0.05. The oxides were reduced to bcc Fe1-xCox alloy at 400 degrees C in H-2 gas and then nitrided at 150 C for 5 or 8 h under NH3 gas flow. XRD and X-ray absorption spectroscopy suggested the nominal alpha ''-(Fe1-xCox)(16)N-2, similar to alpha ''-Fe16N2 was obtained as a mixture with the residual bcc (Fe1-xCox) alloy at x = 0.03 as in the case of the nitrided product without cobalt. The present nitrided product exhibited a larger magnetization of 217Am(2) kg(-1) and a smaller magnetic coercivity of 30mT at x = 0.03 than those for the present products without the Co doping. (C) 2014 The Ceramic Society of Japan. All rights reserved.