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Al–7wt.-% Si–1wt.-% Fe alloy was solidified unidirectionally in the Crystallizer with High Rotating Magnetic Field (CHRMF). The diameter of sample was 8 mm and its length was 120 mm. The parameters of solidification were as follows: solid/liquid interface velocity ~0.082 mm/s, temperature gradient 7+/-1 K/mm, magnetic induction 0 and 150 mT, frequency of magnetic field 0 and 50 Hz. The structure solidified without rotating magnetic field (RMF) showed a homogeneous, columnar dendritic one. The structure solidified by using magnetic stirring showed a dual periodicity. On the one hand, the branches of the “Christmas tree”-like structure known from the earlier experiments contained Al+Si binary eutectic. On the other hand, bands with higher Fe- and Si-content formed in the sample, which were at a larger distance from each other than the branches of the “Christmas tree” structure. The developed microstructure was analyzed by SEM with EDS. The average Si- and Fe-concentrations were measured on the longitudinal section at given places along the length of sample. Furthermore the Si- and the Fe-concentrations close to the bands and among the bands as well as the composition of the compound phases were determined.

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The aim of our work was to develop a monotectic surface layer for bearings by using laser surface-treatment technology. Two kinds of laser surface treatment technology were used. In case of coating-melting technology a Pb layer was first developed by galvanization, then the Pb layer was melted together with the matrix. In case of powder blowing technology Bi powder was blown into the layer melted by laser beam, by Argon gas. The structure of monotectic surface layer was investigated by light microscope and a scanning electron microscope. The volume fraction and size distribution of Pb and Bi particles were determined by image-analyzer.

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