Abstract
The iron aluminides appear as suitable materials with many advantages for use in high-temperature applications. However, a sharp drop in their strength above 600 °C and limited ductility at room temperature are the major obstacles to their mass expansion. There are several possibilities how to improve these negative properties. One possibility is alloying of binary alloys by another element.The main aim of present work is to evaluate the effect of different alloying elements on the coefficient of thermal expansion with respect to phase composition and structure. Generally, the high mechanical temperature properties are affected by alloy structure, and the same could be supposed for the coefficient of thermal expansion (CTE). In this paper, there were studied Fe-26Al-2X (X = Cr, Si, Ta, Zr) alloys. Structure and phase composition were evaluated by SEM, EDX, and EBSD. The CTE’s were examined in a temperature range 460–1200 °C using horizontal dilatometer. Precipitates of ternary phases can beneficially affect the CTE’s values. The lowest and most stable CTE was observed for iron aluminide with Ta-addition.

Key words
iron aluminides, Fe₃Al, structure, coefficient of thermal expansion (CTE)

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