Permalloy B is a Nickel-Iron alloy containing about 45% Nickel and called 45% Permalloy or PB Permalloy, etc.
This material has better soft magnetic properties than electromagnetic steel, but is more expensive because it contains more Nickel. However, since it does not contain Chromium, which is a non-rusting component, its corrosion resistance is inferior to that of 18-8 stainless steel.