Effect of Grain Size and Secondary Particle Refinement on Corrosion Behavior of Cross-rolled Mg-Li-Ca Alloy

Corrosion behavior of cross (cold- and cryo-rolled) Mg-10Li-1.5Ca in 0.6M NaCl was investigated. Cross-rolling was carried out to reduce the thickness to 50% at room temperature. Scanning electron microscopy study was conducted to understand structural transformation. The potentiodynamic polarization test was performed in 0.6M NaCl solution to investigate the corrosion mechanism. The results show that cryo-rolled Mg alloy exhibits superior corrosion resistance than the cold-rolled and as-received alloy due to the extreme grain refinement of alpha-Mg phase and fine homogeneous distribution of intermetallic (Mg2Ca) compounds along the phase boundaries. The different corrosion products such as magnesium hydroxide and lithium hydroxide are formed over the surface. The uniform dense corrosion product Mg(OH)(2) passivates corrosion of Mg-Li-Ca alloy, thereby improving the corrosion resistance of the alloy.