Comparison of corrosion behavior of Mg-1.5Zn-0.6Zr and AZ91D alloys in a NaCl solution

Abstract

The microstructure and corrosion behavior of as-cast Mg-1.5Zn-0.6Zr alloy and a comparative AZ91D alloy were investigated through metallographic observations, X-ray diffraction, electron probe micro-analysis, immersion tests, and cyclic polarization measurements. The Mg-1.5Zn-0.6Zr exhibited a singlephase solid solution characteristic and had fine equiaxed grains, while the AZ91D consisted of a-Mg matrix and b-Mg 17 Al 12 second phases. It was found that Zr is enriched in the center of most grains in Mg-1.5Zn-0.6Zr. Immersion tests showed that the corrosion rate of Mg-1.5Zn-0.6Zr was only about half of that of AZ91D in 5% NaCl solution. The better corrosion properties of Mg-1.5Zn-0.6Zr we owe to the elimination of intensive galvanic corrosion reactions, the formation of much more compact and uniform corrosion films, and the stabilization of magnesium solid solution by Zr. The Mg-1.5Zn-0.6Zr showed a desired uniform corrosion behavior during degradation, which can be reasonably explained by cyclic polarization measurements. The Mg-1.5Zn-0.6Zr alloy displays good corrosion resistance and could be a promising degradable biomaterial. Materials and Corrosion 2015, 66, No. 1 Comparison of corrosion behavior of Mg-1.5Zn-0.6Zr and AZ91D

Laser surface processing of magnesium alloys

“…After 2 days, AZ91 was corroded on some parts of its surface and its material loss increased gradually as shown in figure 5.7. The corrosion morphology of AZ91 in 3.5% NaCl was similar to the morphology caused by 5% NaCl reported in [147]. Raman et al [30] described that the die cast AZ91D showed a steady decrease in corrosion rate up to 6 days, except for the initial 24 hours of a slight increase in corrosion rate.…”

Electrochemical corrosion study of Mg–Al–Zn–Mn alloy in aqueous ethylene glycol containing chloride ions

“…2. The corrosion potential on the forward scan is −1.564 V and that on the reverse scan is −1.579 V. The corrosion potential on the reverse scan is more negative than the forward scan, which indicates that corroded area still acts as anode for further galvanic corrosion and protects the non-corroded area as cathode, resulting in accelerated corrosion in the corroded area, causing the formation of pits [47]. The formation of visible pits on the surface of the alloy is as shown in Fig.…”

Comparativo Da Resistência À Corrosão Da Liga De Magnésio Az31 Submetida Ao Ensaio De Polarização Cíclica

“…Apesar da textura cristalográfica explicar relativamente a corrosão da liga AZ31, não explora a interferência do tamanho de grão. Zhang et al [17] sugeriu que contornos de grão atuam facilitando a passivação reduzindo a taxa de corrosão. Outro estudo [20] indicou ainda que uma possível alternativa para reduzir a taxa de corrosão é reduzir o tamanho de grão.…”