Crystallization and corrosion study of Ca_57.5Mg₁₅Zn_27.5 bulk metallic glasses

The work presents the effect of crystallization state on corrosion resistance of Ca57.5Mg15Zn27.5 bulk metallic glass in Ringer’s solution at 37^◦C. Samples in a form of plates were produced by pressure die casting. Then, they were annealed at 323, 373, and 423 K for 1 h in argon atmosphere. XRD studies were carried out in order to determine the structure before and after annealing. The samples in as-cast and annealed state below crystallization temperature were amorphous. The crystalline structure was detected for samples annealed at 423 K for 1 h. Immersion and electrochemical tests allowed to determine corrosion potential, corrosion current density, and hydrogen evolution volume. The pH changes of solution after immersion were provided. The electrochemical measurements indicated a shift of the corrosion current density from 1.93 mA/cm² for plates in as-cast state to 0.16 mA/cm² for samples annealed at 373 K/1 h, adequately. The corrosion products were mainly identified to be calcium carbonates and calcium/zinc hydroxides.