Možnosti přípravy kompozitů na bázi FeSi-NiAl

Abstract

The diploma thesis deals with the preparation of composites based on FeSi – NiAl, which should serve as suitable tool materials in the future. The composites were prepared in several mass ratios by the method of vacuum induction melting. In order to homogenize the chemical composition and improve the mechanical properties, the composites were heat treated. The microstructure, chemical composition, phase composition, mechanical and tribological properties of the prepared composites were investigated. The prepared alloys showed the character of in-situ composites and had very good mechanical and tribological properties already in the cast state. The structure and phase composition of these samples was quite heterogeneous. As a result of the heat treatment, the chemical and phase composition was homogenized. The samples after heat treatment contained only FeSi and NiAl phases. The heat treatment led to a significant improvement in the mechanical and tribological properties of the samples, which were very well comparable to the values for the conventionally used Vanadis 6 high-speed steel. Thermodynamic modeling confirmed the stability of the system, which is strongly dependent on the content of the FeSi phase, as well as the microhardness values. In the context of phase analysis, Scheil-Gulliver model confirmed the occurrence of intermetallic phases in dependence on the content of elements in the melt during the solidification process. The shortcoming of the prepared composites is their high fragility, which is closely related to high hardness values. Further research would therefore be appropriate to focus on increasing the toughness and machinability of these materials, which could contribute to increasing the competitiveness of cast samples compared to conventionally used toll materials.