<p>The plate-like Fe-rich intermetallics phases significantly deteriorate the mechanical properties in the Al-Si alloys. The evolution of microstructure and mechanical properties of Al-9Si-0.8Fe-<i>x</i>Mo(<i>x</i> = 0, 0.1w t.%, 0.2 wt.%, 0.3 wt.%) alloys were studied, especially the Fe-rich phase. Results show that the matrix for the Al-9Si-0.8Fe alloy mainly consists of primary α-Al, eutectic Si, and long needle-like β-Al₅FeSi phases. As the Mo content increases, the morphology of the Fe-rich phase gradually changes from long needle-like to blocky-like, short rod-like, and finally to star-like. The average ultimate tensile strength (UTS) and elongation (EL) increase from 139.8&#xa0;MPa and 2.7% of the base alloy to 146.2&#xa0;MPa and 6.1% of the 0.2 wt.% Mo alloy, respectively. However, the average elongation decreases to 4.8% of 0.3 wt.%Mo alloy. The coarse and star-like Al(Fe,Mo)Si phase is the main reason for the decrease in elongation. It is concluded that the addition of Mo modifies the needle-like β-Al₅FeSi phase and promotes the formation of α-Al(Fe,Mo)Si phase, which is beneficial in enhancing the ductility and strength of the studied alloys.</p> Graphical Abstract <p></p>