Comparison of corrosion behaviors between Ti-based bulk metallic glasses and its composites

Abstract

The corrosion behaviors of the Ti-based bulk metallic glasses (Zr30.88Ti33.57Cu7Ni5.39Be23.16) as well as the in-situ Ti-based bulk metallic glass matrix composites (Zr28.92Ti42.22Cu6.57Nb6Be16.29) in 0.6 mol/L NaCl, 1 mol/L HCl and 0.5 mol/L H2SO4 solutions were analyzed. The potentiodynamic polarization analyses indicated a drastic increase in the current densities for all specimens in the NaCl and HCl solutions, which could be related to the passive breakdown caused by pitting corrosion. In contrast, no active-passive transition existed in the H2SO4 solution. SEM and EDS analyses were performed to clarify the morphologies and chemical states of the elements prior to and following electrochemical testing. The results demonstrated that both alloys exhibited entirely different corrosion behaviors in the chloride-containing and chloride-free solutions. The surfaces of the samples were locally damaged by a chloride-induced pitting process. Specifically for the composites, a selective dissolution occurred. In contrast, a low portion of corrosion occurred within the chloride-free media. The chemical compositions were identified as the main factor to affect the corrosion performance of the alloys.