Diffusion in nanokristallinen Magnetwerkstoffen

In this work the diffusion in dense and structurally stable nanocrystalline samples was studied without any influence of porosity, relaxation and migration of the grain boundaries. Soft and hard magnetic materials are used as a model system, because in these materials the self diffusion is important for the generation of the magnetic anisotropy. In the soft-magnetic nanocrystalline alloys Fe_7_3_._5Si_1_3_._5B_9Nb_3Cu_1 and Fe_9_0Zr_7B_3, the interfacial diffusion characteristics is determined by intergranular amorphous phases with strongly reduced diffusivities compared to grain boundaries in metals. Indication for a second fast interfacial diffusion path is found for nanocrystalline Fe_9_0Zr_7B_3. In Fe_7_3_._5Si_1_3_._5B_9Nb_3Cu_1 the Ge diffusion is much slower than the Fe-diffusion due to Fe_3Si nanocrystallites with D0_3-ordering. The permanent magnetic material Nd_2Fe_1_4B exhibits an intergranular melting transition which is used for inducing a magnetic texture by hot deformation. Below this intergranular melting transition the product #delta#D_B of interface diffusion coefficient D_B and interface thickness #delta# is similar to that in grain boundaries of coarse grained #alpha#-Fe. A strong increase of #delta#D_B above the intergranular melting transition is observed. (orig.)SIGLEAvailable from TIB Hannover: ZA 5141(6871) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman