Laser rapid solidification improves corrosion behavior of Mg-Zn-Zr alloy

Rapid solidification process is an effective method to improve the corrosion behavior of Mg alloys. In the present study, laser melting, as a typical rapid solidification process, was used to fabricate Mg–5.6Zn–0.5Zr (ZK60). With the increase of laser energy density, the crystalline structures experienced successive changes: clustered finer dendrites→uniform equiaxed grains→coarsened equiaxed grains. Moreover, the fully divorced eutectic α-Mg + Mg₇Zn₃homogeneously distributed along the boundaries of solid solution structure α-Mg. Meanwhile, at a laser energy density of 600 J/mm³, ZK60 was dense with an optimal hardness of 89.2 Hv and hydrogen evolution rate of 0.006 ml cm⁻² h⁻¹. The enhanced corrosion resistance was attributed to the refined grain, homogenized microstructure and extended solid solution caused by laser rapid solidification.