Mn元素对过流冷却过共晶Al-22Si-2Fe-xMn合金显微组织及耐磨性的影响

采用常规铸造和分段式倾斜板过流冷却铸造工艺制备Al-22Si-2Fe-xMn合金,研究表明:过流冷却制备工艺能够改善初生Si形貌及尺寸,但对针状富Fe相作用有限.利用扫描电镜、X射线衍射及透射电镜等手段分析过流冷却条件下Mn元素添加对富Fe相晶体结构的影响,通过摩擦磨损实验研究不同Mn/Fe质量比的过共晶Al-Si合金的硬度及耐磨损性能.结果表明:随着过流冷却铸造过共晶Al-Si合金中Mn/Fe质量比增加,合金中四方结构的长针状富Fe相逐渐减少直至基本消失,当Mn/Fe质量比为0.7时,富Fe相主要为六方结构的块状或鱼骨状α-Al15(Fe,Mn)3Si2相,此时,合金耐磨性较未添加Mn元素时有所提升,磨损机制以磨料磨损方式为主.

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 al-loys 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) 3 Si2 phase. By the time, the wear resist-ance is enhanced compared with no Mn element addition. The wear mechanism gives priority to abrasive wear manner.