Influence of temperature and thermal cycles on the corrosion mechanism of wrought AZ91D magnesium alloy in simulated sea water solution

• Published in: Korose a ochrana materiálu Vol. 67; no. 1; pp. 66 - 77
• Main Authors: Hariesh, S.P., Dhanyanth, P.V., Kughan, S.A., Babu, Dhanush K., Vaira, Vignesh R., Sathiya, P.
• Format: Journal Article
• Language: Czech; English; German
• Published: Prague Sciendo 01.05.2023; De Gruyter Poland
• Subjects: Aluminum; Cathodic protection; Corrosion mechanisms; Corrosion potential; Corrosion rate; Corrosion resistance; Efficiency; Electrochemical corrosion; Grain boundaries; Intermetallic phases; Investigations; Iron alloys; Magnesium alloys; Magnesium base alloys; Microhardness; Oxidation; Pitting (corrosion); Sacrificial anodes; Seawater; Temperature
• ISSN: 0452-599X; 1804-1213
• DOI: 10.2478/kom-2023-0009

This study successfully conducted a comprehensive analysis of the AZ91D magnesium alloy, encompassing micro-structural, mechanical, and corrosion assessments. The microstructure consisted of primary α-Mg crystals and an aluminum-rich α-Mg/β-Mg17Al12 eutectic phase, with intermetallic phases predominantly precipitating at grain boundaries. The microhardness was quantified at 49.96 ± 1.76 HV. Thermostatic tests unveiled a noTab. increase in corrosion rates with rising temperatures, signaling reduced corrosion resistance at elevated environments. Conversely, thermos-cyclic tests showed relatively lower corrosion rates attributed to the accumulation of protective debris on the specimen surface, which could mitigate corrosion during temperature fluctuations. Electrochemical corrosion behavior revealed susceptibility to pitting corrosion at –1.204 V, limiting its application as a sacrificial anode in marine settings.