ABSTRACT
In this chapter, how external fields interact with different materials is discussed, leading to classifications of materials as dia-, para-, ferri•, ferro, and antiferromagnctic materials. While the materials that are inspected by the magnetic NDE method are ferromagnetic, some of the sensors used to detect MFL fields contain ferrites that are more properly classed as ferrimagnetic. Most other common materials, generally referred to as being nonmagnetic, are in fact weakly magnetic and classed according to whether they are repelled or attracted by a strong magnetic field, i.e., dia- or paramagnetic.
