Anticorrosion behavior of ultrafine-grained Al-26 wt% Si alloy fabricated by ECAP

摘要

Ultrafine-grained (UFG) Al-26 wt% Si alloy was obtained through multipass equal-channel angular pressing (EACP) procedure and subsequently tested in 3.5 wt% NaCl solution for the evaluation of electrochemical corrosion. The results show that the ECAPed alloy with increased number of pressing passes obtain lower mass-loss ratios, nobler E corr and E pit, lower I corr values, and higher anode polarization. The improved corrosion resistance of the ECAPed alloy results from the homogeneous UFG structure with the breakage of brittle large primary silicon crystals, which contributes to a higher pitting resistance. The oxidation product with improved adhesion force and protection efficacy can be formed with greater ease on UFG alloys. It implies that grain refinement through severe-plastic-deformation can enhance anticorrosion behavior of hypereutectic Al–Si alloys, besides the well-known strengthening and toughening effects.