Investigation of the Evolution of Magnetic and Acoustic Characteristics as a Result of Annealing of Cold-Deformed Nickel

The change in the magnetic and acoustic properties of nickel as a result of cold deformation and subsequent annealing is investigated. It was found that annealing leads to very significant changes in the magnetic and acoustic properties of nickel. The coercive force decreases 50 times with an increase in the annealing temperature to 800 °C. The Rayleigh coefficient, which characterizes the mobility of domain walls, monotonically increases by a factor of 20 over the entire investigated range of annealing temperatures. The greatest changes in the velocity and damping of longitudinal ultrasonic vibrations occur in the range of recrystallization temperatures. It is shown that to diagnose the structure and magnitude of residual stresses in nickel, it is advisable to determine its magnetic and acoustic parameters.

An inverse scattering method in time-domain electromagnetics

An inverse scattering model, based on the time-domain concepts of electromagnetic theory is developed. Using the first five (zeroth to fourth) moment condition integrals, the Rayleigh coefficient and the next higher order nonzero coefficient of the power series expansion in k (wave number) of the object backscattering response are recovered. The Rayleigh coefficient and the other coefficient thus recovered are used (with the ellipsoidal assumption for the object shape) to determine the dimensions and orientation of the object.Some numerical results of the application of this coefficient recovery technique to conducting ellipsoidal scatterers are presented. The performance of the software system in the presence of normally distributed random noise is also studied.