13th International Conference on Fracture June 16–21, 2013, Beijing, China -7- Fig. 3 Dependence of Shear band angle on β for different α both on tensile side (the blue curves) and on compressive side (the red curves). 4. Conclusions The critical condition for bifurcation of homogenous deformation in MGs has been derived in terms of free volume. It has been found that pressure sensitivity and shear dilatancy exert important effects on the initiation and direction of shear banding. Pressure sensitivity and dilatancy, which are usually coupled together, have the similar trends of influence on the shear band birth and propagation direction. With the enhancement of these two properties, the tension-compression asymmetry of shear banding would be intensified. The instability of constitutive occurs with a smaller c in tension, and the plastic flow is therefore easier to localize into shear bands. This highly localization may lead to a poor tensile ductility at room temperature. The asymmetrical deviation of shear band angle from 45º has been revealed to be mainly ascribed to these two properties. Acknowledgements Financial support is from the National Key Basic Research Program of China (Grant No. 2012CB937500), the NSFC (Grants Nos. 11202221，11132011, 11002144 and 11021262), and the National Natural Science Foundation of China-NSAF (Grant No: 10976100). References [1] R. Huang, Z. Suo, J. H. Prevost,W. D. Nix, Inhomogeneous deformation in metallic glasses. J Mech Phys Solids, 50 (2002) 1011-1027. [2] L. H. Dai, M. Yang, L. F. Liu,Y. L. Bai, Adiabatic shear banding instability in bulk metallic glasses. Appl Phys Lett, 87 (2005) 141916. [3] L. Wang, Z. P. Lu,T. G. Nieh, Onset of yielding and shear band nucleation in an Au-based bulk metallic glass. Scripta Mater, 65 (2011) 759-762. [4] S. X. Song,T. G. Nieh, Direct measurements of shear band propagation in metallic glasses – An overview. Intermetallics, 19 (2011) 1968-1977. [5] H. M. Chen, J. C. Huang, S. X. Song, T. G. Nieh,J. S. C. Jang, Flow serration and shear-band propagation in bulk metallic glasses. Appl Phys Lett, 94 (2009) 141914.
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