Following the approach of earlier studies which have demonstrated that nanocrystalline microstructures can be produced in soft magnetic alloys through the addition of one percent of Cu to Fe based amorphous precursor alloys, it is demonstrated that substantial grain refinement can be produced in alloys of interest for structural applications. Grain sizes of approximately 50 nm were produced in the alloy Fe70Cr15Mo4B10Cu1. Such grain sizes should permit superplastic consolidation of powder or flake at reasonable rates with moderate die pressures at temperatures in the vicinity of 650 degrees C.