Non-destructive methods for materials' state awareness monitoring

Electromagnetic, thermoelectric and other non-destructive evaluation methods offer unique opportunities for materials' state awareness monitoring. A variety of sensors can be built based on these principles to detect and quantitatively characterise subtle environmentally-assisted and/or service-related changes in the state of metals, such as microstructural evolution, phase tran formation, plastic deformation, hardening, residual stress relaxation, increasing dislocation density, etc. In most cases, the detection sensitivity is sufficiently high for the purposes of materials' state awareness monitoring and the feasibility Of the sensing method is mainly determined by its selectivity, or the lack of it, to a particular type of damage mechanism. This paper reviews recent developments in electromagnetic and thermoelectric materials characterisation and offers a feasibility assessment of these non-destructive methods through a couple of representative examples of broad interest.