Effect of ECAP Pass on Corrosion Behavior of High-AI Content Magnesium Alloys

摘要

In view of low strength and poor corrosion resistance of Mg alloys, a Mg-12Al-0.7Si alloy was designed, fabricated and subjected to equal channel angular pressing(ECAP) in order to refine the microstructure. Microstructure observation and electrochemical performance test were conducted to investigate the influence of the microstructural variation subjected to multi-pass ECAP processing on the corrosion behavior of the alloy. The results showed that both a-Mg matrix and β-Mg_(17)Al_(12) of the alloy were significantly refined after processing for different passes (2,4,6,8) through route BC, and the 4-pass ECAPed alloy in 3.5% NaCl solution presents the lowest weight loss, lower corrosion current and higher corrosion potential in the polarization curves. The reason for high corrosion resistance of 4-pass ECAPed alloy and the effects of grain size of the matrix and the particle size, distribution of second phase and dynamic precipitates on corrosion behavior of the alloy were discussed.