Phase equilibria in the Fe–Al–Mo system – Part I: Stability of the Laves phase Fe2Mo and isothermal section at 800 °C

Phase equilibria in the Fe–Al–Mo system were experimentally determined at 800 °C. From metallography, X-ray diffraction and electron probe microanalysis on equilibrated alloys and diffusion couples a complete isothermal section has been established. It is shown that the Laves phase Fe2Mo is a stable phase. The phase Al4Mo, which only becomes stable above 942 °C in the binary system, is the only ternary compound found at 800 °C. For all binary phases the solid solubility ranges for the third component have been established. The D03/B2 and B2/A2 transition temperatures have been determined for a selected alloy by differential thermal analysis and transmission electron microscopy. The results confirm that the D03/B2 transition temperature substantially increases by the addition of Mo, while the B2/A2 transition temperature is about that for a binary alloy with the same Al content.