Zinc Effect On The Properties Of Magnesia 5083 Aluminum Alloy Corrosion And Al - Mg - (zinc Alloy) In The Second Phase Of The Simulation Study

the effect of small addition of Zn on microstructure and corrision property of Al-5083have been studied by means of intergranular corrosion test, exfoliation corrosion test, electro-chemistry characteristic, metallographic microscope,SEM, TEM. Meanwhile, α(Al),β(Al3Mg2) phase and τ(Mg32(Al,Zn)49) phase in bulk form were prepared for the measurement of corrosion potentials by conventional electrochemical equipment. Experiments were also conducted to understand the nature of the β phase-a(Al) matrix galvanic couples, τ phase-a(Al) matrix galvanic couples in NaCl solution and dissolution phenomena associated with Mg-containing phase and Zn-containing phase particles during the corrosion. Experimental results show:(1)(3-phase precipitations are distributed continuously along the grain boundary of Al-5083alloy without Zn after cold-rolled and200℃/2h annealing. In the same state, τ phase precipitations appear in the grain boundary of Al-5083alloy with0.08%Zn. With the increase of Zn content, more τ phase precipitations distributed in the grain boundary. In Al-5083alloy with0.38%Zn, dispersive τ phase precipitations grow in the dislocation near the grain boundary, and τ phase precipitations distribute discontinuously along the grain boundary. For Al-5083alloy with0.7%Zn, τ phase precipitations tend to be continuous again. The susceptibility to exfoliation corrosion of Al-5083alloy without Zn is high, with more Zn content, the susceptibility to corrosion of Al-5083is lower, Al-5083alloy with0.38%Zn has the best performance. However, the susceptibility to corrosion of Al-5083alloy with0.7%Zn is higher than Al-5083alloy with0.38%Zn.(2) Before coupling the corrosion potential of β phase(-1.085v) is lower than the corrosion potential of a(Al) phase(-0.802v), β phase is anode and preferential corrosion. The corrosion potential of τ phase is-0.813v, compare with β phase, potential difference between τ phase and a(Al) phase narrowed greatly. In the process of coupling, P phase and τ phase work as anode. (3) Inside the analog alloys,(3phase and×phase are combine well with a(Al) phase before soaking. After2h soaking, β phase dissolved partly, when only the τ phase-a(Al) phase contact area dissolved partly. After12h soaking, β phase dissolved completely and there are still some τ phases exist.