Development and test of a micromagnetic sensor principle for the characterization of non-ferromagnetic materials

In ferromagnetic materials, magnetic domain walls interact with microstructure over similar mechanisms as dislocations do. This fundamental Observation is the basis of micro-magnetic materials characterization. It is quitelegitlmate to assume that such a correlation exists between micro or electromagnetic and mechanical properties in para- and diamagnetic materials. The electrical conductivity of aluminium does reveal some Information about material properties which can be assessed non-destructively using eddy current impedance measurements. There is much less known about the correlation between the mechanical properties and the magnetic susceptibility of non-ferromagnetic materials such as graphite, aluminium and plastics. There is no commercial non-destructive method which uses the concept of magnetic susceptibility for the characterization of dia- and paramagnetic materials. Some principles have been proposed in this work which use the magnetic susceptibility of the materials to determine the para- or diamagnetic properties and display their lateral distribution as an intensity map. Experiments also show that some of these principles are highly sensitive to even the smallest ferromagnetic impurity In non-ferrous materials.