Effects of Laser Surface Remelting on Microstructure and Corrosion Properties of Mg-12Dy-1.1Ni Alloy
Guangli Bi, Siqi Chen, Jing Jiang, Yuandong Li, Tijun Chen, Xiaobo Chen, Duyao Zhang, Dong Qiu, Mark Easton
Abstract
Abstract 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 α -Mg, lamellar Mg 12 DyNi phase with an 18R-long period stacking order (LPSO) structure and Mg 24 Dy 5 . 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 μm. 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 μA/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.