Effect of Mn element on the microstructure and wear resistance of hypereutectic Al-22Si-2Fe-xMn alloys produced by inclined cooling

Al-22Si-2Fe-xMn alloys were prepared by conventional casting and a segment-based inclined cooling plates. It is shown that inclined cooling preparation technology can improve the morphology and size of primary Si, but has limited effect on the needle-shaped Fe-rich phase. The effect of Mn addition on the crystal structure of Fe-rich phase under the condition of inclined cooling was analyzed by scanning electron microscopy (SEM), X-ray diffraction (XRD) and transmission electron microscopy (TEM). The hardness and wear resistance of hypereutectic Al-Si alloys with different Mn/Fe mass ratios were also researched by friction and wear test. Results indicate that long needle-shaped Fe-rich phase of tetragonal structure decreases gradually and disappears basically in alloys as the Mn/Fe mass ratio increases by inclined cooling casting hypereutectic Al-Si alloys. When the Mn/Fe mass ratio is 0.7, Fe-rich phase is mainly hexagonal structure block-shaped or fishbone-shaped α-Al₁₅(Fe, Mn)₃Si₂ phase. By the time, the wear resistance is enhanced compared with no Mn element addition. The wear mechanism gives priority to abrasive wear manner.