Magnetization reversal and hyperfine field in cold-rolled Ni-Fe alloys

The coercive force Hc. saturation magnetization Ms, and squareness of cold-rolled binary Ni-Fe alloys were studied at 300°K over the composition range 0 to 100 percent Ni. These alloys were cold-rolled into thin foils with a reduction in thickness higher than 99 percent. In general, Hcand of the Ni-Fe alloys of various compositions showed marked frequency responses when the magnetizaion loops were cycled with fields having very low frequencies varying from 0.02 to 2 Hz. The hyperfine fields in the Ni-Fe alloys at the iron sites were determined by means of the Mössbauer effect. The Mössbauer patterns were used to analyze the magnetic heterogeneities caused by the cold-rolling. As concluded from this work, these heterogeneities seem to become appreciably larger near the Invar composition and may be responsible for the observed peaks in the magnitudes of Hcand of the alloys with 30 and 32.5 percent Ni.