Corrosion Behaviour of AZ and ZA Magnesium Alloys in Alkaline Chloride Media

Abstract

Corrosion behaviour of AZ and ZA magnesium alloys in untreated, aerated, and deaerated chloride media was investigated. The influence of impurity, alloying element, and oxygen on corrosion potential, rate, and pitting was examined in alkaline media saturated with Mg(OH) 2 at pH 9 and 25• C. After 8 h immersion, slightly less active corrosion potentials were generally observed in deaerated than oxygen containing solutions. AZ91D and ZA104 alloys recorded much lower corrosion rates in deaerated medium as compared to AZ91E, ZAC 10403 (0.3Ca), and ZACS1040305 (0.3Ca+ 0.5Sr). Generally, ZAC alloy showed the highest corrosion rate, followed by ZACS alloy, and both showed a constant value in the three media with or without oxygen. The effect of oxygen is then dependent on the alloy properties and is not a simple acceleration of the cathodic reaction but could cause also inhibition and/or passivation. Pit depth and distribution were influenced by alloy composition. The pits were found deeper and more localized on AZ and more uniformly dispersed on ZA alloy surfaces.

Manufacturing of Mg-Ti Couples at Different Heat Treatment Temperatures and Their Corrosion Behavior in Chloride Solutions

“…These parameters are βc, βa (cathodic and anodic Tafel slopes), E Corr (corrosion potential), j Corr , corrosion rate (R Corr ), and R P (polarization resistance). The values recorded in Table 1 were obtained as reported in the previous research [25,28,30]. The curves of Figure 5 and the data listed in Table 1 indicated that the coupling of Ti with Mg at 540 °C greatly reduced j Corr and R Corr values and raised R P values.…”

“…The data obtained from Figure 5 reveal that the recorded currents in the cathodic branch for all samples shifted towards the corrosion current density (j Corr ) by the less negative increase of potential values. The reaction occurs on the cathode for these AZ31 alloy and Mg-Ti couples and unlike all other materials was the evolution of hydrogen even in the neutral NaCl solution as per the following equation [27,28]; 2H + + 2e − = H 2 …”

Organo-metallic electrolyte additive for regulating hydrogen evolution and self-discharge in Mg–air aqueous battery

“…Ultimately, preventing the liberation of electrons at the anode could prevent hydrogen evolution and anode dissolution. 35,36…”

Study of the Corrosion Process of AZ91D Magnesium Alloy during the First Hours of Immersion in 3.5 wt.% NaCl Solution

“…Recyclability and good machinability are additional attributes that make them attractive materials to manufacture low weight parts [4]. In spite of these attractive attributes, the well-known chemical instability in aqueous environments is a core issue for magnesium alloys, limiting their applicability [5][6][7].…”