Correlation of Magnetic Permeability and X-Ray Diffraction Line Broadening in Cold-Worked Iron

Abstract

The permeability of annealed and cold-worked iron (0%–3.8% plastic tensile strain) was measured at field levels up to 0.8 Oe. and found to obey the Rayleigh relationship, μ=μ0+vH. The results show that the reciprocal of either Rayleigh constant, μ0 or v, varies linearly with the square root of the plastic strain value and that their ratio (μ0/v) is essentially independent of the degree of plastic strain. X-ray diffraction lines were also recorded for each sample and the line width was found to vary linearly with the square root of the plastic strain. The x-ray line broadening produced by cold work is ascribed to small particle size, caused by dislocations with an average spacing of D. The constant μ0, taken as a measure of reversible domain wall motion, is shown to be directly proportional to D, in support of certain models which have been proposed for hindrances to wall motion.