Improved stress-corrosion-cracking resistance of Mg-3Al-3Ca alloy enabled by coupled addition of Y and Nd

Utilizing Mg-Al-Ca alloys for lithium-ion battery shell holds great promise to further propel the lightweight of electric vehicles, and their service life is strongly dependent on their corrosion and especially stress corrosion cracking (SCC) resistance. Therefore, in this work, a Mg-3Al-3Ca alloy was first modified by simultaneous addition of rare earth elements Y (1 wt%) and Nd (1 wt%), and then its corrosion and SCC resistance in the specific 1 mol/L LiPF6 6 electrolyte for lithium-ion batteries were investigated by means of immersion and slow strain rate tensile (SSRT) tests. Compared with the counterpart Mg-3Al-3Ca alloy, decreased number and size of the Al2Ca 2 Ca phase, significant grain refinement and texture weakening, uniform stress concentration distribution were found in the modified Mg-3Al-3Ca-1Y-1Nd alloy. Consequently, the effects of micro-galvanic corrosion, anodic dissolution (AD) and hydrogen embrittlement (HE) in the Mg-3Al-3Ca-1Y-1Nd alloy were simultaneously decreased. Meanwhile, denser MgF2 2 corrosion product films which have protective effect against corrosion were also formed in the Mg-3Al-3Ca-1Y-1Nd alloy during the corrosion testing. As a result, the total weight loss and hydrogen evolution rate during immersion, and the SCC sensitivity coefficient of the modified Mg-3Al-3Ca-1Y1Nd alloy were decreased significantly, showing an improved corrosion and SCC resistance.