I presume that we are talking about magnetically soft alloys.
This somewhat depends on the field strength and temperature. At very high field strengths the highest saturation is at lower Co contents, say about 35% (Fe2Co), this is also true as you go to temperatures lower than room temp.
If you cut or machine a part it will need a good anneal to recover maximum saturation.
Additions of V or Cr help to lower the initial permeability, but lower the saturation.
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