Effect of heat treatment on the corrosion behavior of amorphous Mg-Ni-Nd alloys

The effect of heat treatment on the corrosion behavior of seven amorphous melt-spun Mg-Ni-Nd alloys containing 10-20 at.% Ni and 5-15 at.% Nd has been studied. Hydrogen evolution testing was used to determine the dissolution rate of the heat-treated specimens immersed in a 3% NaCl solution saturated with Mg(OH)₂. The dissolution rates of the partially crystallized specimens were found to be lower than those of the untreated specimens, while the fully crystallized specimens exhibited marked deterioration of corrosion resistance. X-ray diffraction (XRD) and transmission electron microscopy (TEM) studies on the heat-treated specimens revealed precipitation of Mg₃Nd, Mg₁₂Nd, and Mg₂Ni phases during the crystallization. TEM results show that the partially crystallized structure consists of uniform dispersion of either Mg₃Nd or Mg₂Ni in the amorphous matrix. In contrast, multiple phases precipitate in the fully crystallized specimen.