The Influence of Introduced Strains on the Exfoliation Corrosion Behavior of Mg-14mass%Li-1mass%Al Alloy

Abstract

Mg-Li alloys have much better formability than traditional Mg alloys. However, the corrosion resistance of Mg-Li alloys are low due to Li addition and cold-worked Mg-Li alloys sustain exfoliation corrosion, which is serious problem for practical use of Mg-Li alloys [1]. According to our previous report, the elongated grains may be the cause of the exfoliation corrosion. In this study, the exfoliation corrosion behavior of Mg-14mass%Li-1mass%Al (LA141) alloy processed by equal channel angular extrusion (ECAE) is characterized to see the corrosion morphology of the samples introduced more grains than rolling. The specimens processed by rolling showed only elongated grains and the ones processed by ECAE (Route A) at 2 and 4 times showed elongated grains and partially equiaxial grains and in the samples fabricated by ECAE (Route Bc) at 2 and 4 times, equiaxial grains were found by optical microscopy. In corrosion examination, the specimens of rolling and ECAE (Route A) developed exfoliation corrosions and the samples of ECAE (Route Bc) didn’t sustain exfoliation corrosion. This results were consistent with our previous report. Then the corrosion behavior of rolled and ECAEed samples were focused. The evaluation of the time until crack initiation and the number of cracks were employed to see the corrosion morphology of the samples