|About this Abstract
||2011 TMS Annual Meeting & Exhibition
||Bulk Metallic Glasses VIII
||Fatigue Crack Growth in Zr-Based Bulk Metallic Glasses
||Jamie J. Kruzic, Sarah L. Philo, Maximilien E. Launey
|On-Site Speaker (Planned)
||Jamie J. Kruzic
Fatigue crack growth rates were measured for Zr<SUB>44</SUB>Ti<SUB>11</SUB>Ni<SUB>10</SUB>Cu<SUB>10</SUB>Be<SUB>25</SUB> and Zr<SUB>58.5</SUB>Nb<SUB>2.8</SUB>Cu<SUB>15.6</SUB>Ni<SUB>12.8</SUB>Al<SUB>10.3</SUB> bulk metallic glasses (BMGs). Growth rate data overlapped considerably for both. The former BMG was tested in different initial free volume states, different residual stress states, and in both ambient air and dry nitrogen environments. Fatigue crack growth rates were relatively unaffected by the initial free volume state. This was attributed to the formation of a fatigue transformation zone of increased local free volume at the fatigue crack tip. When residual stresses were not annealed out, it was found that the fatigue threshold and fracture toughness increased due to residual compressive stresses at the sample surfaces. Finally, it was observed that testing in a dry nitrogen environment significantly increased the fatigue threshold, suggesting a corrosion fatigue mechanism in ambient air. A similar environmental effect was observed for the Zr-Nb-Cu-Ni-Al BMG in ambient air, but at very different growth rates.