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Crack nucleation at the Sigma 9(2(2)over-bar1) symmetrical tilt grain boundary in tungsten

: Cheng, Y.; Mrovec, M.; Gumbsch, P.

Postprint urn:nbn:de:0011-n-753026 (1.1 MByte PDF)
MD5 Fingerprint: bca7ca4fb9cf111eeb81b07070c056e6
Erstellt am: 11.7.2009

Materials Science and Engineering, A. Structural materials, properties, microstructure and processing 483-484 (2008), S.329-332
ISSN: 0921-5093
ISSN: 1873-4936
International Conference on the Strength of Materials (ICSMA) <14, 2006, Xian>
Zeitschriftenaufsatz, Konferenzbeitrag, Elektronische Publikation
Fraunhofer IWM ()
crack nucleation; grain boundary; atomistic simulation

Crack nucleation mechanisms and nucleation conditions are still poorly understood. Experimental evidence suggests that crack nucleation mainly occurs when growing twins, slip or persistent slip bands collide with grain boundaries. We therefore started to investigate these processes by atomistic simulations. As a first step, we present here simulations of crack nucleation at the sigma 9 (221) grain boundary in tungsten resulting from the interaction with dislocations. Symmetric twin boundaries and most other high-angle grain boundaries are relatively stable and act as barriers to dislocation motion. When a dislocation by such grain boundaries, a stress concentration develops at the absorbing site and a crack is nucleated there. Crack nucleation is investigated under different loading condit ions. Our results show that crack nucleation is aided significantly by additional dislocation activity. The relevant mechanisms are significantly more complex than captured by simple pile-up models.