The influence of Al3Zr precipitates on electrochemical anodic and cathodic reactions of an Al-0.1Zr (wt%) model alloy

This study investigates the role of Al3Zr precipitate in Al-Zr-based alloys used for high temperature low-sag (HTLS) conductor wire applications. Operating at temperatures up to 250°C, these wires are susceptible to water condensation which leads to corrosion attack. While Al3Zr is known for enhancing mechanical properties, its impact on corrosion has been underestimated. The study explores Al3Zr formation due to different heat treatments on pitting corrosion and hydrogen transport. Both of phenomenas are crucial in stress corrosion cracking (SCC). Corrosion testing demonstrated that larger precipitates increase pitting susceptibility and affecting repassivation rates. The study employed techniques like cyclic voltammetry (CV) and hydrogen permeation testing to characterize hydrogen behavior, showing that precipitate size and coherency significantly impact hydrogen diffusion and trapping. Overall, the study highlights the intricate relationship between Al3Zr precipitates, microstructure, and corrosion behavior in Al-Zr-based alloys, providing insights for alloy design and wire performance improvement.