Microstructure and corrosion properties of micro-beam plasma remelted Mg-12Dy-1.1Ni alloy

Microstructure and corrosion properties of micro-beam plasma remelted (MPRMed) Mg-12Dy-1.1Ni (wt%) alloy were investigated. The as-cast alloy was mainly composed of α -Mg, lamellar Mg 12 DyNi phase with a 18R-long period stacking order (LPSO) structure, and Mg 24 Dy 5 phase. After micro-beam plasma remelting (MPR), the grain size of the as-cast alloy was remarkably refined to 11 µm, and the amounts of 18R-LPSO phase increased from 18.3% to 26.0% and distributed as continuous network. The electrochemical and immersion tests indicated that the MPRMed alloy exhibited a lower mass loss rate 0.31 g/(cm 2 ·d) and corrosion current density (605.3 µA/cm 2 , and ∼38.5% reduction after MPR) than the as-cast alloy in 0.1 mol/L NaCl solution. The improved corrosion resistance of the MPRMed alloy was primarily ascribed to the uniform microstructure, denser corrosion products and continuous distribution of 18R-LPSO phase.