中国有色金属学报(英文版)
Transactions of Nonferrous Metals Society of China
Vol. 28 No. 6 June 2018 |
(1. Department of Materials Science and Ceramic Engineering, Imam Khomeini International University, Qazvin, Iran;
2. School of Metallurgy and Materials Engineering, Iran University of Science and Technology, Tehran, Iran)
Abstract:The effect of Fe-impurity (0.2%-2%, mass fraction) on the microstructure, dry sliding wear, and friction properties of Al-15Mg2Si 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 Mg2Si particles from irregular dendritic form to smaller particles with polyhedral shapes, refined the pseudo-eutectic structure, and led to the formation of hard b-Al5FeSi 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.
Key words: Al-Mg2Si; in-situ composite; tribology; sliding wear; friction