Thermomagnetic properties of nanocrystalline Fe-Si alloys with high Si content

We report the structural and temperature dependent magnetic properties of Fe100−xSix (0≤x≤40) alloy powders synthesized by a mechanical alloying process over a wide composition range. We have observed from X-ray diffraction (XRD) that non-equilibrium solid solution could be obtained up to 35 at% Si within 100 h of milling. As-milled powders have fine crystallites with size around 9 nm and dislocation density in the order of 1017 m−2. The variations of saturation magnetization and lattice constant with Si substitution show a good correlation between the structural and magnetic properties. Thermomagnetic studies reveal the presence of different magnetic phases in the milled Fe-Si powders with high Si content, which depends on both composition and milling time. Curie temperature of Fe-Si solid solution decreases gradually at a rate of 1.45 K/at% Si with increasing Si content. These results are in close agreement with the XRD data obtained for presently investigated nanocrystalline Fe-Si alloys.