Ni-Mn系新高透磁率合金「Nimalloy」の特性におよぼすW添加の影響について

Abstract

Masumoto et al. discovered previously that alloys near the Ni3Mn composition exhibit high-permeability by proper heat treatment. The alloys were named “Nimalloy”. In the subsequent work on the effect of additions of various elements on the properties of nickel-manganese alloys, the highest initial permeability of 76000 and the highest maximum permeability of 441000 have been obtained.The results on tungsten additions to nickel-manganese alloys show that the optimum cooling rate to attain the highest permeability in each alloy decreases gradually in general with increasing tungsten content, so that the alloys were baked for a long time at various temperatures below the order-disorder transformation point after slow-cooling from 900°C. With increasing tungsten content, the permeability of nickel-manganese alloys increases first gradually and then rapidly attains a maximum value, after which it decreases gradually.The alloy consisting of 76.65%Ni, 19.23%Mn and 4.12%W exhibits the highest initial permeability of 13720 when cooled at a rate of 5°C/hr from 900°C and reheated at 380°C for 430 hr, and the highest maximum permeability of 60700 when cooled at a rate of 3°C/hr from 900°C The latter heat-treated alloy shows a magnetic hysteresis loss of 47.47 erg/cm3/cycle and a coercive force of 0.0321 Oe for the maximum magnetic induction of 5000 G, an intrinsic magnetic induction of 6232 G at an effective magnetic field of 900 Oe and an electrical resistivity of 58.7 μΩ-cm at 20°C.