13th International Conference on Fracture June 16–21, 2013, Beijing, China -6- is ductile despite gallium in liquid phase on the surface, and, therefore, the recovery of ductility at 465 K is not considered to be induced by formation of the intermetallic compound. Various mechanisms of LME have been proposed, and it is still controversial whether crack initiation or crack propagation is a controlling process [1]. The specimen pulled at 423 K did not indicate clear necking (Fig. 4(c)), and the stress-strain curve shows abrupt drop after it reaches the maximum (Fig. 2). These indicate that a crack propagates very fast once a crack starts to move, and, therefore, a micro crack nucleation or start of crack motion seems to be especially blocked at this temperature. 5. Conclusion Polycrystalline silver is embrittled by liquid gallium. Recovery from the embrittlement occurs if the contact time with liquid metal is long. This is considered induced by the formation of an intermetallic compound. Ductility trough is also observed as a function of test temperature in this solid and liquid metal couple. However, this ductility trough is not connected to forming the intermetallic compound. References [1] for a review: B. Joseph, M. Picat, F. Barbier, Liquid metal embrittlement: A state-of-the-art appraisal. Eur Phys J AP, 5 (1999) 19-31. [2] F. A. Shunk, W. R. Warke, Specificity as an aspect of liquid metal embrittlement. Scripta metall, 8 (1974) 519-526. [3] G. Nicaise, A. Legris, J. B. Vogt, J. Fost, Embrittlement of the martensitic steel 91 tested in liquid lead. J Nucl Mater 296 (2001) 256-264. [4] K. Ina, H. Koizumi, Penetration of liquid metals into solid metals and liquid metal embrittlement. Mater Sci Engng A 387-389 (2004) 390-394. [5] S. P. Lynch, Metal-induced embrittlement of materials. Mater Characterization 28 (1992) 279-289. [6] K. Sakai, H. Koizumi, Time dependent embrittlement of polycrystalline Ag by liquid Ga, Procedia Engng 10 (2011) 643-648. [7] K. Arakawa, K. Yamamoto, K. Sakai, H. Koizumi, to be submitted.
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