Effect of Fe-impurity on tribological properties of Al-15Mg_2Si composite

Fe杂质对Al-15Mg_2Si复合材料摩擦性能的影响（英文）

The effect of Fe-impurity（0.2%-2%, mass fraction） on the microstructure, dry sliding wear, and friction properties of Al-15 Mg2 Si composite was investigated using a pin-on-disk tester under the applied pressures of 0.25, 0.5 and 1 MPa at a constant sliding speed of 0.13 m/s. According to the results, Fe modified the primary Mg2 Si particles from irregular dendritic form to smaller particles with polyhedral shapes, refined the pseudo-eutectic structure, and led to the formation of hard b-Al5 Fe Si platelets in the matrix. In spite of hardness improvement by these microstructural changes, the resistance of the composite against dry sliding wear was impaired. SEM examination of the worn surfaces, wear debris, and subsurface regions confirmed the negative effect of b-phase on the tribological properties. It was found that b-particles were fractured easily, thereby decreasing the potential of the substrate to resist against sliding stresses and giving rise to the instability and easy detachment of tribolayer as large delaminated debris. The friction results also revealed that Fe slightly decreased the average friction coefficient, but increased the fluctuation in friction.

研究了Fe杂质(0.2%~2%,质量分数)对Al-15Mg_2Si复合材料的显微组织、干滑动磨损和摩擦性能的影响。摩擦实验采用销盘式试验机,压力分别为0.25、0.5和1 MPa,固定滑动速度为0.13 m/s。结果显示,Fe使初始Mg_2Si颗粒从不规则枝晶状转变为多面体形状的较小颗粒,细化伪共晶结构,并导致基体中形成硬质相β-Al_5Fe Si片晶。尽管这些显微组织的变化提高了复合材料的硬度,但其抗干滑动磨损的能力却受到了损害。磨损表面、磨屑和下表层的SEM结果证实了β相对摩擦学性能的不利影响。β相颗粒较易断裂,从而降低基体抗滑动应力的能力,造成摩擦层的不稳定,使其易剥离,形成大的剥落碎片。摩擦实验结果还表明,Fe降低材料的平均摩擦因数,但增加摩擦因素的波动。