Abstract:0.5% (molar fraction) Sb was added to Mg₆₁Cu₂₈Gd₁₁ glass forming alloy to improve its thermal stability and corrosion resistance. The crystallization kinetics of Mg₆₁Cu₂₈Gd₁₁ and (Mg_0.61Cu_0.28Gd_0.11)_99.5Sb_0.5 amorphous alloys was investigated under continuous heating. The temperatures of glass transition, onset and peak crystallization for the two glasses exhibit strong heating-rate dependence. The activation energies for the onset and peak crystallization were determined based on the Oawza plots. Vogel-Fulcher-Tamman equation analysis shows that the larger strength parameter and much longer relaxation time are obtained due to the Sb addition. The corrosion properties of the two glassy alloys were studied by means of potentiodynamic and immersion tests. Compared with the parent alloy, (Mg_0.61Cu_0.28Gd_0.11)_99.5Sb_0.5 glassy alloy exhibits a superior corrosion resistance in Cl⁻-containing alkaline solution, as indicated by the lower passive current density and corrosion rate. Based on the point defect model, the effect mechanism of Sb addition on corrosion resistance of Mg-Cu-Gd glassy alloy is carefully identified.

Key words: Mg-based bulk metallic glasses; Sb; crystallization kinetics; corrosion resistance