The basis of the technology lies in the fact that in metallurgical alloys, many micro/ultra-structural processes create regions that are analogous to dissimilar metal junctions – i.e. on either side of the semi-coherent/incoherent interfaces created by the processes are regions that have a different Seebeck coefficient.  Examples are inclusions and precipitates in alloy matrices, accumulation of fatigue damage (that creates regions of intense deformation separated by regions of almost no deformation – akin to the formation of a physical interface) and all corrosion processes.