A Highly Fatigue-Resistant Zr-Based Bulk Metallic Glass

The strength-normalized fatigue endurance strength of the bulk metallic glass (BMG) Zr52.5Cu17.9Ni14.6Al10Ti5 (Vitreloy 105) has been reported to be the highest for any BMG; however, to date, there has been no explanation of why this material is so much better than other Zr-based compositions. In this study, the fatigue-crack growth behavior of Zr52.5Cu17.9Ni14.6Al10Ti5 was compared in ambient air vs dry nitrogen environment. The excellent fatigue life behavior is attributed to a relatively high fatigue threshold (Delta K (TH) a parts per thousand 2 MPaaem) and a lack of sensitivity to environmental effects on fatigue-crack growth in ambient air, as compared to other Zr-based BMGs. Fatigue life experiments conducted in ambient air confirmed the excellent fatigue life properties with a 10(7)-cycle endurance strength of similar to 0.24 of the ultimate tensile strength; however, it was also found that casting porosity, even in limited amounts, could reduce this endurance strength by as much as similar to 60 pct. Overall, the BMG Zr52.5Cu17.9Ni14.6Al10Ti5 appears to have excellent strength and fatigue properties and should be considered as a prime candidate material for future applications where good mechanical fatigue resistance is required.