[en] By this research the question is investigated whether and how an anisotropic precipitation structure can be obtained by means of an external magnetic field. At first it is found by observation that platelets, precipitated in Fe-N solid solutions, can be oriented during the coarsening process. A similar effect is observed in Fe-Si solid solutions. This effect is then analysed on the base of theoretical models for nucleation, growth and coarsening. It is found that - in agreement with the observations - orienting is feasible during coarsening and not during nucleation and growth. In addition the magnetisation curve and particularly the coercitive force of crystals with anisotropic precipitation structures is measured in dependence on the direction of the external magnetic field. This is done at Fe-N solid solutions containing ferromagnetic particles and at Fe-M-Au solid solutions containing nonmagnetic precipitates. The magnetic properties are found to vary considerably with the direction of the magnetic field