The longitudinal Kerr effect has been used to observed domain structure during dc and 60-Hz magnetization in conventional (110) [001] grain oriented 3% Si–Fe as a function of applied tensile stress parallel to the rolling direction. The observed domain processes indicate that the source of the Villari reversal in this material is demagnetizing fields occurring at grain boundaries and at the sheet surface. In grains where the [001] tilted out of the sheet surface, demagnetizing fields were produced when 90° flux closure domains were eliminated by applied tensile stress. During magnetization under applied tensile stress, these demagnetizing fields restabilized the original unstressed closure structure. High speed movies of the magnetization process in grains with perfect plane orientation revealed that although the 180° wall spacing was decreased by applied tensile stress the flux became very nonuniform due to the buildup of grain boundary demagnetizing fields and the average 180° wall velocity was not decreased. The observed domain processes explain the magnetic properties previously observed in this material under applied tensile stress, e.g., decreased maximum permeability, the appearance of negative magnetostriction and lack of improvement in core loss at stress levels in excess of 500 psi.
A quantified maximum entropy method is applied to the optimisation of analytical information from FPR spectra of free radicals. Statistically meaningful errors are produced for the positions and intensities of all spectral peaks and considerable improvements in sensitivity compared with conventional spectral enhancement procedures are obtained with measurements of the intensities of spectra of known radicals.
The dependence of coercivity, resistivity and mechanical hardness on aging time and temperature was studied in solution treated and quenched 5 mil thick 82Co-12Fe-6Ti tape and related to changes in microstructure observed using transmission electron microscopy of thin foils. The results indicate that a fine scale periodic array of coherent precipitates is responsible for the increase in coercivity in this alloy in the solution treated, quenched, and aged state. This periodic coherent phase mixture must coarsen appreciably in order to produce a significant increase in coercivity, whereas mechanical hardness is significantly increased by the development of the modulated structure from the onset of precipitation.
The magnetic domain structure was studied in a 0.17 cm wide ×32 μm thick ribbon of a Ni40Fe40P14B6 amorphous alloy (Metglas Alloy 2826 manufactured by Allied Chemical during dc and ac magnetization after stress relief annealing and under various levels of applied tensile stress. The longitudinal Kerr effect was used for domain observation. Under an applied tensile stress, a simple antiparallel 180° wall structure was observed and the flux density of the sample correlated well with the observed 180° wall displacement. The domain wall spacing/sheet thickness ratio (2L/d) was extremely large (∠48) and decreased with increasing magnetizing frequency and applied tensile stress; the dependence of 2L/d on magnetizing frequency is characteristic of systems in which domain wall motion is eddy current limited. Significant improvements in losses and permeability during magnetization at power frequencies will occur if methods can be found to reduce these rather large domain wall spacings.
Optical and electron microscopic techniques were used to characterize surface morphologies of (110) [OOI] oriented 3% Si-Fe sheets, and to relate these observations to measurements of core loss. Smooth surfaces were found to produce significantly lower losses than rough surfaces. Smooth surfaces were obtained by annealing with an A1 2 0 3 separator or by chemical polishing. Rough surfaces were produced by annealing with an MgO separator, annealing for a time too short to reduce the surface oxides, annealing in oxidizing atmospheres, and by chemical etching.
The effect of N 2 in the anneal atmosphere on the texture and the associated magnetic properties of Al bearing 3% Si-Fe was investigated. Cold rolled/decarburized samples were annealed in either 100% H 2 or a mixture of 25% N 2 -75% H 2 . Orientations of grains were determined using selected area electron channeling. Misoriented (i.e., not
