添加Zn对5083铝合金组织和腐蚀性能的影响

摘要

5083Al alloy, 5083Al alloy containing 0.7% Zn (mass fraction), ?Al3Mg2) phase, t(Mg32(Al,Zn)49) phase were prepared by cast metallurgy. The microstructures and corrosion properties of alloys by 180 ?, 2 h annealing after cold-rolled were studied by TEM, exfoliation corrosion test and polarization curve measurement. The electrochemical properties of ?phase, t-phase and a(Al) were studied by polarization curve measurement. The results show that rod-like ?phase precipitations are distributed continuously along the grain boundary of 5083A1 alloy without Zn and the susceptibility to exfoliation corrosion is high, while globular r-phase precipitations are distributed discontinuously along the grain boundary and formed uniformly in the grain interior of 5083A1 alloy with Zn and alloy has low exfoliation corrosion susceptibility. The corrosion potential of?phase, t-phase and a(Al) is -1.085 V, -0.813 V and -0.812 V respectively, and t-phase improves the corrosion performance of Al-5083 alloy.%通过铸锭冶金法制备5083铝合金、加0.7％Zn(质量分数)5083铝合金、β(Al3Mg2)相和τ(Mg32(Al,Zn)49)相,对添加Zn和未添加Zn的5083合金进行冷轧180℃,2h退火处理后,利用剥落腐蚀测试、极化曲线测定和透射电镜研究少量Zn对冷轧退火后5083铝合金组织和腐蚀性能的影响,并通过电化学测试研究β相、τ相与α(Al)的电化学特征.研究结果表明:退火后不含Zn的合金中杆状的β相在晶界连续分布,合金的剥落腐蚀等级为EA,腐蚀电位为-0.651V.而加入0.7％Zn的合金在相同状态下,τ相部分取代了β相,且其主要呈球状,在晶界、晶内不连续分布,合金的剥落腐蚀等级为PB,腐蚀电位为-0.54 V.加少量Zn明显提高5083合金的耐蚀性.测得β相的腐蚀电位(-1.085V)比α(Al)的腐蚀电位(-0.812 V)低,而τ相的腐蚀电位(-0.813V)与α(Al)的腐蚀电位基本相同,τ相的形成缩小第二相与铝基体的电位差,优化合金的耐腐蚀性能.