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

Abstract

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.

Micro-electrical discharge machining of difficult-to-machine materials: A review

“…This may be related to the formation of carbides that contain Cr in the layer. Lin et al 71 performed EDA on 5083 Al alloy with a 75% by mass of ferrosilicon electrode. It was reported that the thickness of iron–silicon layer increases with an increase in pulse duration and discharge current (Figure 39).…”

Microstructural Characteristics of Electric Discharge Alloyed Layers on Spheroidal Graphite Cast Iron with Different Electrode Materials

“…The main factors that affect the thickness of alloyed layers are the nature of tool electrodes and the parameters of the EDA process. 16,17,20,23,25,34) Some researchers point out that the melting point, thermal and electric conductivity of the electrodes all affect the thickness. 23,25,34) Wang et al 23) examined the mechanism with which the EDM process was employed to form strengthening layers in the surface of stainless steel and the main factors that affected this mechanism.…”

Synthesis of electrical discharge metal matrix composite coating through compacted semi-sintered electrode and its tribological studies

“…The transmission electron microscopy (TEM) study revealed the matrix formation of fine needles of Si particles, blocks of nano-size Al 4 Fe 5 Si and Al 3 Fe 4 particles. In addition, this layer exhibited good corrosion resistance in NaCl aqueous solution [8,9]. Nihal et al [10] used hydroxyapatite powder mixed dielectric liquid and proved that the collision of the powder separates the main discharge which made the surface rich in additives.…”