Effect of niobium additions on the structure and magnetic properties of equiatomic iron-cobalt alloys

Abstract

The structure of equiatomic iron-cobalt alloys containing 1, 2 and 3 wt% niobium has been studied using a variety of techniques, including X-ray diffraction, scanning and transmission electron microscopy and differential thermal analysis. It has been found that niobium is effective in reducing the kinetics of ordering to the B2 structure and of anti-phase domain growth, even though the solubility is only 0.3-0.5 wt %. The magnetic properties (coercive force and saturation magnetization) and the electrical resistivity of the three alloys have also been determined.

Influence of alloying elements on the mechanical properties of FeCo–V alloys

“…For example, the decrease in saturation magnetization and increase in coercivity of FeCo due to vanadium and niobium are shown in Fig. 7 [13,17]. As in FeCo -V alloys, saturation magnetization decreases with increasing amounts of the paramagnetic second phase.…”

“…In addition, vanadium addition decreases the permeability and increases the coercivity of FeCo [3,16,17]. Table 2 summarizes the effect of other alloying elements on the saturation magnetization of FeCo [3,13,15]. The saturation magnetization decreases from 1 to 5% for addition of each alloying elements.…”

“…Moreover, the solid solubility of most of the alloying elements is less than 1 at% in FeCo. Addition of such alloying elements in excess of their solid solubility results in precipitation of paramagnetic phases, which further increases the coercivity through pinning the domain wall movements [13,16].…”

“…Effect of vanadium and niobium contents on the (a) saturation magnetization and (b) coercivity of FeCo alloy[13,17].…”

Thermal Stability of the Nanostructured Powder Mixtures Prepared by Mechanical Alloying

“…Also, the phase transformation temperature from bcc to fcc structure in the Fe50Co50 powders is rather milling time independent (~982°C). The lower resistivity of Fe50Co50 compared to that of pure Fe at 300 K [52] and the higher Curie temperature of Fe50Co50 suggest that there is less scattering of the conduction electrons by the magnetic excitations. Thus, the Curie temperature cannot be clearly observed because there is a phase transformation from the bcc to fcc form at 985°C.…”