Study On The Corrosion Properties Of Zn6Al3Mg Alloys And Zn11Al3Mg Alloys

In this paper,Zn6Al3 Mg series alloys and Zn11Al3 Mg series alloys were prepared by medium frequency induction melting furnace.The microstructure,phase composition,morphology and composition of the corrosion products,alloy corrosion morphology were investigated by metallographic microscope,scanning electron microscope(SEM),X-ray diffraction(XRD)and X-ray energy dispersive spectroscopy(EDS).The corrosion potential,self-corrosion current and AC impedance characteristics of Zn6Al3 Mg series alloys and Zn11Al3 Mg series alloys in 3.5wt% Na Cl solution were investigated using the CHI614 e electrochemical workstation.On this basis,the corrosion mechanism of Zn Al Mg alloy was studied and discussed.The results show that the main phase composition of Zn6Al3 Mg alloys is dendritic Zn-rich phase,Al-rich phase and netty Zn-Al-Mg Zn2 ternary eutectic structure.The main phase composition of Zn11Al3 Mg alloys is massive Al-rich phase,Mg Zn2 phase and netty Zn-Al-Mg Zn2 ternary eutectic structure.The weight loss rate of Zn6Al3 Mg alloys and Zn11Al3 Mg alloys is approximately 1/2 that of pure zinc.In the process of immersion corrosion,the selfcorrosion current of Zn6Al3 Mg alloys and Zn11Al3 Mg alloys increases speed is slower than pure zinc.The reason is that in the early stage of immersion corrosion,the preferential corrosion phases Mg Zn2 and Zn in the Zn Al Mg alloy are corroded.There are 41 figures,31 tables and 86 referencesin this paper.The surface of the alloy rapidly forms protective needle-like gel membranes with good adhesion and poor conductivity: Zn6Al2(OH)16CO3(LDH)and Zn5(OH)8Cl2.This corrosion product can hinder the electrochemical reaction and slow the rate of increase of the corrosion rate of the alloy.0.1wt% of rare earth elements Ce and La are added to Zn6Al3 Mg alloy and Zn11Al3 Mg alloy,increasing the number of inhomogeneous nucleation sites during solidification of the alloy.Ce and La form an intermetallic compound with Al and Zn,which can hinder the growth of the dendritic Zn-rich phase,refine the grain structure of the alloy,homogenize its surface potential,and increase the uniform corrosion of the alloy.