Regulating microstructures and mechanical properties of Al-Fe-Ni alloys

Mechanical properties of Al-Fe-Ni eutectic alloys have been investigated based on the nominal mass fraction of eutectic phase, and the added Fe/Ni mass ratio. The X-Ray diffraction, scanning electron microscopy equipped with energy dispersive spectroscopy and transmission electron microscope have been used to identify phase composition, characterize microstructure and crystal structure of A1(9)FeNi phase, respectively. The results demonstrate that the nominal mass fraction of eutectic phase control the presence of primary phase. The tensile strength slightly increases, and the ductility deteriorates sharply as the volume fraction of primary phase increases. The Fe/Ni mass ratio has the profound effect on the microstructures (i.e., size and shape) of primary phase. When the Fe/Ni ratio is approaching to 1, the primary phase becomes rod-like shape, which can enhance the ductility of alloys over the flake-like phase. The increasing cooling rate can effectively reduce the eutectic grains size and primary phase fraction, and further significantly improve mechanical properties of the alloys.