Remelting and alloying of Al-Si-alloys

Abstract

For various substrate materials, different types of laser treatments are known. During the last three years one could see worldwide activities in surface remelting of Al-alloys. For surface alloying of Aluminum based materials transition metals and/or silicon are suitable additions. Extremely high hardness values comparable to those of steel sheets were obtained by laser surface alloying using high power CO2-lasers. The present paper is a critical review of these data and reports on hardness values that were obtained in homogeneous surface layers by alloying Si and/or transition metals into the surface. In addition it is shown how heterogeneous nuclei can influence the homogeneity and the microstructure in the melted layer. The influence of flux additions on the effectiveness of alloying preplaced elements into the surface is demonstrated. The metallurgy of surface melting more developed multi-component layers into the substrate was possible using a new coating technique which allows easy and cheap preplacement.For various substrate materials, different types of laser treatments are known. During the last three years one could see worldwide activities in surface remelting of Al-alloys. For surface alloying of Aluminum based materials transition metals and/or silicon are suitable additions. Extremely high hardness values comparable to those of steel sheets were obtained by laser surface alloying using high power CO2-lasers. The present paper is a critical review of these data and reports on hardness values that were obtained in homogeneous surface layers by alloying Si and/or transition metals into the surface. In addition it is shown how heterogeneous nuclei can influence the homogeneity and the microstructure in the melted layer. The influence of flux additions on the effectiveness of alloying preplaced elements into the surface is demonstrated. The metallurgy of surface melting more developed multi-component layers into the substrate was possible using a new coating technique which allows easy and cheap prepla...