How to determine possible interactions of silicide and aluminide in preparation of composites

Abstract

Silicide - aluminide composites could be considered as potential tool materials, because of high wear resistance and thermal stability. Recently, the alloys based on iron aluminide and silicide were tested, but they found to be very brittle due to the occurrence of brittle Fe-Al- Si ternary phases. On the other hand, in TiAl- Ti5Si3 composite, no ternary phase was formed during sintering, even though it can be expected based on thermodynamics. Therefore, this paper aims on finding the way how to test potential interaction between silicide and aluminide phase during preparation of these composites on the example of the FeSi - NiAl composite. The approach, proposed in this work, deals with the pre-sintered iron silicide, which was surrounded by aluminide powder in the sintering die and spark plasma sintered again. After that this model sample was annealed under various conditions and the FeSi - NiAl interface was observed. The experiments proved that no chemical reaction between FeSi and NiAl phase occurs during sintering and thermal exposure at 1000 degrees C. The visible interfacial layer is just a result of mutual diffusion.