Synthesis of Mg–Zn–Ca metallic glasses by gas-atomization and their excellent capability in degrading azo dyes

• Mg–Zn–Ca metallic glass powders were synthesized by gas-atomization.
• The phase structure of powders was affected by the composition and the size.
• Degradation capacity of powders is determined by phase constituents and Mg content.
• Nano-whiskers are distributed loosely on the reacted surface of the glassy powder.

Mg–Zn–Ca powders of Mg63+xZn32−xCa5 (x = 0, 3, 7 and 10) with the diameter from 2 μm to 180 μm were synthesized by gas-atomization. The relationship among powder morphology, the composition, glass forming ability, thermal stability, corrosion resistance and the capacity in degrading azo dyes for these powders was investigated. It is shown that fully glass powders with the particle diameter < 150 μm can be atomized for alloys with x ≤ 7. These Mg–Zn–Ca metallic glass powders exhibit remarkably superior corrosion resistance and degradation capacity in Direct Blue 6 solution to their crystalline counterparts and Fe powders. Nano-whiskers were formed uniformly and loosely on the reacted surface of the Mg70Zn25Ca5 glassy powder, which is considered as the mechanism of high degrading capacity for these Mg–Zn–Ca glassy alloys. This work will contribute to the development of massive production of high quality metallic glass powders with excellent capability in degrading azo dyes.