Microstructural and Corrosion Characteristics of Iron-Silicon Alloyed Layer on 5083 Al Alloy by Electrical Discharge Alloying Processing

摘要

In the study, the surface modification of 5083 Al alloy by electrical discharge alloying (EDA) with a 75 mass% ferrosilicon electrode was used to examine the effects of machining parameters (discharge current, pulse duration and duty factor) on the thickness, hardness and surface roughness of the alloyed layer. Experiment results reveal that the thickness tends to increase with the increase in the pulse duration and discharge current. In addition, the micro-hardness evidently higher compared to the substrate. The hardness also increases with the increasing discharge current and pulse duration. TEM examinations show that the matrix of the alloyed layer is an amorphous-like structure, whereas the matrix contains fine needle-like Si particles, block-like Si particles and nano-size Al(4.5)FeSi and Al(13)Fe(4) particles. The results of EPMA compositional analysis indicate that the alloying elements (Si and Fe) contained in the electrode effectively dissolve in the alloyed layer of 5083 Al alloy and the content of the dissolved alloying elements gradually decreases with the increase in the distance from the discharge surface. Furthermore, the surface roughness increases with the increase in the discharge current and pulse duration. It is also found that the alloyed layer with composite microstructures exhibits sufficient corrosion resistance to NaCl aqueous solutions. [doi:10.2320/matertrans.M2010363]