The Study Of Corrosion Behavior And Interfacial Diffusion Of Al/Mg/Al And Magnesium Alloy

In this paper, The microstructures and morphologies of the AZ80 rolling plate, AZ31 rolled plate, LZ91 rolling plate, LA101 hot extrusion rods, ZE42 hot extrusion plate were observed by optical microscopy(OM), scanning electron microscopy(SEM) and X-ray diffraction. Polarization curve and corrosion rate of them were measured in salt water immersion test by electrochemical test system and various experimental analysis method, and corrosion rate of two kinds rolling composite board(Al/LZ91/Al and Al/ZE42/Al) at different temperature and holding time were also measured. Effects of different temperature & hold time of annealing on two kinds of rolling composite board(Al/LZ91/Al and Al/ZE42/Al) interfacial diffusion and tensile properties were investigated.The experimental conclusions are as follows:(1) In NaCl solution magnesium alloy(AZ31,AZ80,LZ91,LA101,ZE42) corrosion potential is 1.5V, cathodic hydrogen evolution reaction, anode active dissolution. Surface of magnesium alloy are pitting corrosion occurred, has obvious corrosion pits, surface is structure of loose corrosion products is Mg(OH)2. Corrosion resistance from poor to good order is: ZE42 < LZ91 < LA101 < AZ31 < AZ80.(2) In 5.0 wt% NaCl solution, annealing treatment was not significantly improve corrosion resistance of the Al/LZ91/Al and Al/ZE42/Al composite panels, but the corrosion rate was increased. Corrosion mechanism of composite panel is caused by galvanic corrosion which exacerbates edge to internal diffusion.(3) In the temperature and humidity are larger steam environment, magnesium alloy and its composite board are priority to electrochemical corrosion of oxidation reaction, magnesium alloy surface darkening, corrosion products are Mg(OH)2. Annealing treatment accelerated corrosion of the composite panels in the steam environment, and galvanic corrosion led to a three layer board separately.(4) After annealing treatment on Al/Mg/Al three-layer composite plate, diffusion of Mg, Al and other elements occurred,interface consists of α-Mg phase, Mg17Al12 phase, Al3Mg2 phase and α-Al phase equally. After annealing temperature 300℃ holding time 1h, tensile strength and elongation of plate were best, namely: 130 MPa and 15.8%.