Iron-cobalt alloys are the most important soft magentic materials which exhibit unique magnetic properties such as high magnetic saturation, high curie temperature and low magnetic loss and therefore are widely used in different industrial applications such as electric motors, information storage, telecomunications, high power transformators and recently in areospace industries. Although FeCo alloys are famous due to their magnetic properties, their application in different industries have drawn some attention to their mechanical properties as well. The formability of FeCo alloy is very low and so is not suitable for fabrication of magnetic parts by any deformation process such as rolling or extrusion. This mechanical property (formability) can be improved by addition of small amount of alloying elements such as V, Nb, Ni and Cr. The strength, hardness and wear resistance of these alloys may also be improved by reinforcement with hard ceramic particles. The main challenge in this respect is to maintain the magnetic properties when the mechanical properties are improved. So in this research work production of FeCo-Nb alloys and their reinforcement with WC particles was investigated using mechanical alloying technique. Elemental Fe, Co, Nb and WC powders were used as starting materials and the products, FeCo-Nb alloy and (FeCo-Nb)WC, were characterized for their magnetic properties, namely magnetic saturation and coercivity using a Vibrating Sample Magnetometer (VSM). Phase transformation, microstructural characteristics were studied by X-ray Diffraction (XRD), Scaning Electron Microscope (SEM). The results indicated that a phase transformation for Cobalt from fcc to hcp occurred at the first three hours of milling. This was followed by dissolution of Co in Fe and a nearly complete FeCo-Nb solid solution was obtained after 10 hr milling. Addition of WC to the starting powders resulted in a more efficient milling such that the alloy formation took place at a shorter time (5 hr). The SEM micrographs also indicated that a homogeneous composite with finely disstributed WC particles have been produced after 10 hr milling. Regarding the magnetic properties the results showed that addition of 2 wt% Nb to FeCo alloy improved the magnetic saturation and coercivity compared to the conventional FeCo and FeCo-V alloys. Reinforcement of FeCo-Nb alloy with WC particles did not change the magnetic properties severely but increased the microhardness from 470 Hv for FeCo-Nb alloy to 850 Hv for (FeCo-Nb)WC composite. Annealing the composite powders at 500?C increased the magnetic saturation from 160 emu/g to 180 emu/g and also decreased the coercivity to about 20 Oe. Annealing at higher temperatures (700 and 900?C ) declined the magnetic properties due to formation of an antimagnetic phase called the Eta phase (Fe 6 W 6 C). By sintering the composite powders at 1000?C and 1200?C and in H 2 atmosphere, bulk specimens were produced. The results showed that 1000?C was not sufficient for proper sintering while sintering at 1200?C was successful with less than18% porosity and a fine diersion of WC particles in the FeCo-Nb matrix. Furthermore hardness of the sintered sample, measured 720 Vikers and the magnetic saturation and coercivity of this sample were measured 194 emu/g and 39 Oe respectively. Keywords: Soft magnetic materials, FeCo alloy, magnetic properties, Mechanical alloying, composite, nanostructure
