Abstract
Ni-Fe-Ta alloys were vacuum melted in hydrogen atmosphere over the temperature range 1050 to 1350°C and then cooled at various rates of 100 to 8100°C/hr from a temperature above their order-disorder transformation points. Magnetic properties of the alloys were improved by high-temperature heating in hydrogen atmosphere. The highest values of 75000 in initial permeability and 650000 in maximum permeability are obtained for the alloy of 73.00%Ni, 11.60%Fe and 15.40%Ta when cooled at the rate of 800°C/hr after heating at 1250°C for 0.5 or 2 hr, respectively. The latter heat-treated alloy shows a coercive force of 2.9 m Oe and a hysteresis loss of 3.9 erg/cm3/cycle for a maximum magnetic induction of 5 kG. The electrical resistivity of this alloy is 70.1μΩ-cm, with Vickers hardness 211. The high permeability of Ni-Fe-Ta alloys appears to be due to the removal of impurities, homogenization of alloys and grain growth by high-temperature heat treatment and also to the low value of magnetostriction in the proper ordering state of the alloys.
