Mechanisms of elevated temperature fatigue crack growth in Zr–Ti–Cu–Ni–Be bulk metallic glass
- 作者：Hess ; Peter A. ; Dauskardt ; Reinhold H.
- 关键词：Metallic glasses ; Fatigue ; High temperature
- 刊名：Acta Materialia
- 出版年：2004
- 期刊代码：1_13596454
- 类别：ms
- 出版时间：July 12, 2004
- 卷：52
- 期：12
- 页码：3525-3533
- 文件大小：455 K
摘要
Zr-based bulk metallic glasses (BMGs) are surprisingly susceptible to cyclic fatigue processes. In the present study, the sub-Tg elevated temperature fatigue crack growth behavior was examined. The fatigue threshold, ΔKTH, was found to increase from 
hs/BQ1.GIF>1.1 to hs/BQ1.GIF>1.4 MPam1/2 as testing temperature was increased from 100 to 220 °C. Low levels of fatigue crack closure were apparent and not associated with threshold behavior. Regular arrays of micron-sized elongated ridges formed parallel to the crack growth direction in the near-threshold fatigue crack-growth regime at elevated temperatures. A model for ridge formation based upon the planar stability of a Mode I crack was proposed. Ridge wavelengths and amplitudes were accurately predicted with respect to changes in applied stress intensity and temperature, and ridge angles were calculated on the basis of a Mohr–Coulomb yield criterion.
hs/BQ1.GIF>1.1 to hs/BQ1.GIF>1.4 MPam1/2 as testing temperature was increased from 100 to 220 °C. Low levels of fatigue crack closure were apparent and not associated with threshold behavior. Regular arrays of micron-sized elongated ridges formed parallel to the crack growth direction in the near-threshold fatigue crack-growth regime at elevated temperatures. A model for ridge formation based upon the planar stability of a Mode I crack was proposed. Ridge wavelengths and amplitudes were accurately predicted with respect to changes in applied stress intensity and temperature, and ridge angles were calculated on the basis of a Mohr–Coulomb yield criterion.