Experimental investigation and thermodynamic modeling of the ternary Al-Cu-Fe system

摘要

The constitution of the ternary system Al-Cu-Fe in the region above 40 at.% Al at 600 ℃ is investigated by means of x-ray diffraction, metallography, scanning electron microanalysis with energy dispersive x-ray spectroscopy, and differential thermal analysis. The phase equilibria in the Al-rich corner are clarified by the valuable experimental evidence for the four-phase reaction L + λFe_4Al_(13) reversible (Al) + ω at 600.7 ℃ and by the experimental findings that the phase αFe_4CuAl_(23) was not detected. A thermodynamic modeling of the Al-Cu-Fe system was then performed over the entire composition range by taking into account the phase diagram data above 560 ℃ from the literature and the present work. This work challenged the modeling of the considerably complex order-disorder phase transition between bcc_A2 and bcc_B2 phases and the miscibility gap of bcc_B2 phase using the modified sublattice model.