Ni-Mn系新高透磁率合金「Nimalloy」について

抄録

The magnetic properties of ferromagnetic Ni-Mn alloys containing less than 35.56% manganese have been measured at room temperature, after cooling at various rates from 900°C, with ring-form specimens punched from thin plates, and the relation between the magnetic permeability and order-disorder transformation of Ni₃Mn (23.78 wt%Mn) has been investigated. It has been found that the initial and maximum permeabilities become larger as the cooling rate becomes smaller; the former shows only one maximum against the composition, and the latter two. An alloy containing 21.80% manganese has the best properties when cooled at the rate of 5°C/hr from 900°C; the initial permeability is 5090, the maximum permeability 12490, the magnetic hysteresis loss 18.5 erg/cm³/cycle (B_max=2000 G), the coercive force 0.027 Oe (B_max=2000 G), and the specific electric resistance 60.5 μΩ cm at 20°C. This alloy can be forged and rolled more easily than permalloys and has been named “Nimalloy” which is an abbreviation of Ni-Mn alloys.