Stress Corrosion and Corrosion Fatigue Crack Growth of Zr-Based Bulk Metallic Glass in Aqueous Solutions

Crack-propagation tests on a bulk metallic glass (BMG), Zr55Cu30Ni5Al10, were conducted either in aqueous sodium chloride (NaCl) solutions or in high-purity water under sinusoidal cyclic loading or sustained loading. Although the crack growth rate in high-purity water was almost identical to that in air, the rate in the NaCl solution was much higher than that in air, even in a very low concentration of NaCl such as 0.01 mass pct. In a 3.5 mass pct NaCl solution, the time-based crack growth rate during cyclic loading, da/dt, was determined by the maximum stress-intensity factor, Kmax, but was almost independent of the loading frequency and the stress ratio, and the rate was close to that of stress corrosion cracking (SCC) under a sustained loading.