Effects of Chromium and Tungsten Additions on the Characteristic Properties of New High Magnetic Permeability Alloys “Nimalloy” in the System of Nickel and Manganese

Abstract

Since the discovery of high magnetic permeability alloys “Nimalloy”, a series of experiments has been carried out on the effects of additions of various elements on the properties of Nimalloy, and the highest initial permeability of 76000 and the highest maximum permeability of 441000 have been obtained in the case of Cr additions to Ni–Mn–Fe alloys. In the present investigation, it has been found that with increasing Cr and W additions to Ni–Mn binary alloys the cooling rate at which the highest permeability is attained becomes smaller gradually. Therefore, in most cases, the alloys were slow-cooled from 900°C and further baked for a long time at a temperature below the order-disorder transformation point. With increasing contents of Cr and W, both the initial and maximum permeabilities of the alloys increased gradually to the maximum values and afterwards decreased gradually. By the addition of Cr, the alloy composed of 80.93% Ni, 17.13% Mn and 1.94% Cr showed the highest value of 17000 in initial permeability and the alloy of 80.47% Ni, 17.30% Mn and 2.23% Cr, the highest value of 103000 in maximum permeability. In the case of W addition, the alloy composed of 76.65% Ni, 19.23% Mn and 4.12% W showed the highest values of 13720 in initial permeability and 60700 in maximum permeability.