New insights into the damage mechanism of a Zr-Ti based bulk metallic glass under cavitation erosion in deionized water

Bulk metallic glass (BMG), also known as amorphous alloy, which is almost free of structural defects such as grain boundaries and dislocations, is expected to achieve superior cavitation erosion (CE) resistance due to possessing high hardness, elastic modulus and superior corrosion resistance. Compared with the extensively studied crystalline alloys, the damage mechanism of amorphous alloys under CE remains unclear. Herein, the CE behavior and damage mechanism of a Zr-Ti based BMG in deionized water was systematically investigated. Relevant results showed that Zr-Ti based BMG exhibited robust resistance to CE in deionized water. The incubation period of CE was found to be about 4 h, which was significantly longer than that of stainless steels, copper alloys and titanium alloys. Moreover, grazing incidence X-ray diffraction analysis indicated that crystallization was absent throughout the entire CE process. Differential scanning calorimetry demonstrated an increasing free volume of BMG with prolonged CE time, which further led to the formation of micro-porosity by the free volume aggregation, and eventually gave rise to the CE damage.