Fatigue Behavior of Bulk-Metallic Glasses
Gongyao Wang (University of Tennessee), Yoshihiko Yokoyama (), Xiaoqing Jin (), Leon Keer (), Xie Xie (University of Tennessee), Peter Liaw ()
Crack initiation and growth: methods, applications, and challenges
Wed 1:30 - 2:50
Barus-Holley 161
Fatigue studies are reviewed for the Zr-Cu-Al bulk-metallic glasses (BMGs). BMGs have no grain boundaries and dislocations. Their excellent performance properties for structural applications, such as high yield strength, hardness, and fracture toughness, have promising potentials. Understanding how to predict the fatigue life of BMGs is crucially important for their selection as structural materials. In our research, the nature of likely fatigue mechanisms for BMGs is reviewed. Fatigue cracks, arising from machining/polishing damage, were found to initiate from shear bands near defects. At the crack tip, a plastic-zone creation is observed through the formation of many shear bands, and the fatigue crack is reported to grow along these shear bands. The size of the plastic zone correlates with fracture-mechanics quantities, and each fatigue cycle produces a fine striation instead of a single coarse one. We propose a shear-band mechanism to explain the characteristics of the fatigue-crack-propagation behaviour. Numerical computations, based on linear-elastic-fracture mechanics, yield reasonably good agreement with experimental results. Acknowledgements: The projects are supported by the National Science Foundation programs (DMR-0231320, DMR-0909037, CMMI-0900271, and CMMI-1100080) with Drs. C. Huber, D. Finotello, C. V. Cooper, A Ardell, and E. Taleff as program directors.