THE CORROSION RESISTANCE OF AN Al-Li ALLOY IN 3. 5 wt.-% NaCI
(General Research Institute for Non ferrous Metals, Beijing,100088, China)
Abstract: The influences of heat treatment and pH value on corrosion potential and cyclic polarization curve of an AI-Li alloy in 3.5 wt，一%NaCl were investigated. Microstructures of the alloy were combined to analyze and explain the development of cyclic polarization curves and the variation of corrosion potential within 24 h. The results revealed that the preferential dissolution of the precipitates in the, alloy increased the susceptibility of the alloy to localized corrosion. Prolonging artificial ageing treatment caused heavy precipitation of Tl phase in matrix and both precipitation of phases containing copper and widening of PFZ along the grain boundary, and thus worsened the corrosion resistance. In strong acidic or strong alkaline solution the alloy demonstrates poor corrosion resistance.
Key words: Al-Li alloy, Corrosion, polarization, pitting, passivation.