Experimental Investigation of Phase Equilibria in the Fe-Nb-Ta System

The phase equilibria in the Fe-Nb-Ta ternary system at 1200, 1100 and 1000 °C were experimentally investigated. The microstructure of each sample was observed using scanning electron microscopy, and phase compositions were measured by energy dispersive spectrometry. The constituent phases of typical samples were analyzed with x-ray diffraction. The experimental results indicated that the continuous solid solution phases, Fe 2 (Nb,Ta) and Fe 7 (Nb,Ta) 6 , were formed between Fe 2 Nb and Fe 2 Ta and Fe 7 Nb 6 and Fe 7 Ta 6 , respectively, and no ternary compounds were found in this system in these isothermal sections. Based on the experimental phase equilibria data obtained in the present work, three isothermal sections at 1200, 1100 and 1000 °C were constructed.