Fatigue pre-cracking and toughness of the Zr55Cu30Al10Ni5 bulk metallic glass for two oxygen levels

Samples of a Zr-based bulk metallic glass with a small (1000 appm) or very small (less than 300 appm) oxygen content are pre-cracked by fatigue and tested for toughness evaluation. It is shown that oxygen trapped in oxide dendrites eases the initiation of a straight crack and embrittles the glass even at such low concentrations. In contrast, when oxygen is dissolved in the glass, fatigue crack initiation becomes difficult and it is not possible to get a crack passing straight through the glass.