Effects of Laser Surface Remelting on Microstructure and Corrosion Properties of Mg-12Dy-1.1Ni Alloy

Effects of laser surface remelting (LSR) on microstructure and corrosion properties of as-cast Mg-12Dy-1.1Ni (wt.%) alloy were investigated. The as-cast alloy was mainly composed of alpha-Mg, lamellar Mg12DyNi phase with an 18R-long period stacking order (LPSO) structure and Mg24Dy5. After LSR treatment, fine and compact 18R-LPSO phase reprecipitated on dendrite boundaries as a continuous network. In addition, the volume fraction of the LPSO phase remarkably increased to 34.9% and the grain size of as-cast alloy was refined to ca. 4 mu m. Electrochemical and immersion tests indicated that the LSR-treated alloy exhibited a lower weight loss rate (2.8 +/- 0.2 mg/cm(2)/h) and corrosion current density (160.1 +/- 20.7 mu A/cm(2), and of 37% reduction after LSR) than the as-cast alloy in 0.1 M NaCl solution. The improved corrosion resistance of the LSR alloy was mainly ascribed to the grain refinement and continuous distribution of 18R-LPSO phase on dendrite boundaries.

Automated summary

The effects of laser surface remelting (LSR) on microstructure and corrosion properties of as-cast Mg-12Dy-1.1Ni alloy were investigated. LSR treatment resulted in grain refinement and the formation of a continuous network of 18R-LPSO phase on dendrite boundaries, leading to improved corrosion resistance of the alloy.