Microstructural and Corrosion Characteristics of Alloying Modified Layer on 5083 Al Alloy by Electrical Discharge Alloying Process with Pure Silicon Electrode

摘要

This study examines the surface modification of 5083 Al alloy by electrical discharge alloying (EDA) process, using pure Si as anelectrode. Al alloy surface was modified by the EDA process to explore the effect of machining parameters (discharge current, pulse duration andduty factor) on the thickness, hardness and roughness of the alloyed layer. Samples were analyzed by scanning electron microscopy (SEM),electron probe analysis (EPMA) and X-ray diffraction. Since pure Si was used as an electrode, the alloyed layer had high concentration of Sifrom 2 mass% (the position in the layer at substrate side) to 12 mass% (the position in the layer close to surface side). Experimental results revealthat the thickness of the alloyed layer had a concave downward relationship with the discharge current and pulse duration. High hardness(� Hv 250) of the alloyed layer was obtained. The results of X-ray diffraction indicate that the primary phase in the substrate was �-Al, whilethere were composite phases containing �-Al and Si particles in the alloyed layer. Additionally, the alloyed layer exhibited as good corrosionresistance as 5083 Al alloy in aqueous NaCl.