Effect of Tantalum Additions on the Properties of New High Magnetic Permeability Alloys “Nimalloy” in the Nickel and Manganese System

Abstract

Masumoto et al. have previously discovered that alloys in composition near to Ni₃Mn exhibited a high permeability when developed to an optimum degree of order, and these alloys were named Nimalloy. In the subsequent work on the effect of various additives on the properties of Ni–Mn alloys, the highest initial permeability of 121000 and the highest maximum permeability of 643000 have been obtained with Ni–Mn–Fe–Cr–Mo alloys.
The results of Ta additions to Ni–Mn alloys show that with increasing Ta content, the permeability of Ni–Mn alloys at first increases gradually, goes through a maximum rapidly, and then decreases gradually. The highest initial permeability of 20470 is obtained on the alloy composed of 75.88% Ni, 19.47% Mn and 4.65% Ta when cooled at a rate of 240°C/hr from 900°C and baked at 440°C for 64 hr, and the highest maximum permeability of 84800 on the alloy of 75.37% Ni, 19.08% Mn and 5.55% Ta when cooled at a rate of 240°C/hr from 900°C and baked at 440°C for 65 hr. The latter alloy shows a coercive force of 0.0253 Oe and a magnetic hysteresis loss of 50.85 erg/cm³/cycle for the maximum magnetic induction of 5000 G, and its electrical resistivity being 52.7 μΩ-cm at 20°C.