抄録
Kobayashi and two of the present authors discovered in a previous work that nickel-manganese alloys exhibit high permeability in the concentration of less than about 24% manganese, and named them Nimalloy. Much subsequent work has been carried out on the effects of additions of various elements on the properties of nickel-manganese alloys and obtained the highest initial permeability of 76000 and the highest maximum permeability of 441000. In the present paper, the effect of aluminium additions on the characteristic properties of nickel-manganese alloys have been studied. The results show that the optimum cooling rate for attainment of the highest permeability in each alloy increases in general with increasing aluminium content. Thus the alloy containing 78.95% Ni, 19.85% Mn and 1.20% Al showed the highest initial permeability of 10780 when cooled at a rate of 400°C/hr from 900°C and the alloy containing 78.81% Ni, 19.56% Mn and 1.63% Al exhibited the highest maximum permeability of 73200 when cooled at a rate of 800°C/hr from the same temperature; the latter shows a magnetic hysteresis loss of 9.49 erg/cm3/cycle and a coercive force of 0.0121 Oe for the maximum magnetic induction of 2000 G, and a specific electrical resistivity of 61.0 μΩ-cm at 20°C.
