Precipitation of Fe-rich intermetallic phases in liquid Al-13.58Si-11.59Fe-1.19Mn alloy

To contribute to the understanding of the Al–Fe–Mn–Si system, an exhaustive analysis of the intermetallic phases formed during thermal analysis experiments and specific isothermal treatments was carried out. In this work, three different phases were identified: the extensively reported β and α phases and the τh phase. The τh phase has been reported for the ternary Al–Fe–Si system, but not for the quaternary Al–Fe–Mn–Si system. Nonetheless, the present results suggest that the formation of the τh phase upon solidification of the alloy can be stabilized in the quaternary Al–Fe–Mn–Si system, with respect to the monoclinic θ-Al3Fe phase in the ternary Al–Fe–Si system, due to the Mn addition. The τh phase was unambiguously identified with the help of complementary techniques such as SEM/EDS, X-ray diffraction and Mössbauer spectroscopy.