ABSTRACT
This chapter looks at applications of magnetic measurements to materials characterization and to nondestructive evaluation (NDE) of materials. The ability to resolve features at length scales down to 40 nm, with little or no surface preparation required and under ambient atmosphere conditions, make this technique ideal for practical high-resolution magnetic evaluation of material surfaces. In order to evaluate the variation of materials properties from one location to the next, imaging techniques can be used. The effects of stress on the magnetic hysteresis properties of steels are of interest because they have applications to NDE of large-scale structures. The magnetic Barkhausen effect (MBE) consists of discontinuous changes in flux density, known as Barkhausen jumps. Magnetoacoustic emission is an effect that is very closely related to MBE. It is sometimes referred to as acoustic Barkhausen. The chapter reviews magnetic detection and characterization of defects or flaws in magnetic materials.
