Characterization of Crack-Tip Dislocations and their Effects on Materials Fracture

Abstract:

Article Preview

Three-dimensional structure of crack tip dislocations were investigated by combining scanning transmission electron microscopy (STEM) and electron tomography (ET) in silicon single crystals. P-type (001) silicon single crystals were employed. <110> cracks were introduced from an indent on the (001) surface. The specimen was heated at 873K in order to introduce dislocations at the crack tips. The specimen was thinned to include the crack tip in the foil by an iron milling machine. STEM-ET observation revealed the three-dimensional structure of crack tip dislocations. Their Burgers vectors were determined by using an invisibility criterion. The local stress intensity factor was calculated using the dislocation characters obtained in the observation in this study, indicating that the dislocations observed were mode II shielding type dislocations.

Info:

Periodical:

Materials Science Forum (Volumes 654-656)

Main Theme:

Edited by:

Jian-Feng Nie and Allan Morton

Pages:

2307-2311

Citation:

K. Higashida et al., "Characterization of Crack-Tip Dislocations and their Effects on Materials Fracture", Materials Science Forum, Vols. 654-656, pp. 2307-2311, 2010

Online since:

June 2010

Export:

Price:

$38.00

[1] C. St. John: Philos. Mag. Vol. 32 (1975), p.1193.

[2] J. Samuels and S.G. Roberts: Proc. R. Soc. Lond. A Vol. 421 (1989), p.1.

[3] M. Brede and P. Haasen: Acta Metall. Vol. 36 (1988), p. (2003).

[4] K. Higashida, N. Narita, M. Tanaka, T. Morikawa, Y. Miura and R. Onodera: Philos. Mag. A Vol. 82 (2002), p.3263.

[5] K. Kaneko, R. Nagayama, K. Inoke, W. -J. Moon, Z. Horita, Y. Hayashi and T. Tokunaga: Scripta Mater. Vol. 52 (2005), p.1205.

[6] P.A. Midgley, M.W. Weyland, J.M. Thomas and B.F.G. Johnson: Chem. Commun. Vol. 2001), p.907.

[7] K. Kimura, S. Hata, S. Matsumura and T. Horiuchi: J. Electron Microsc. Vol. 54 (2005), p.373.

[8] J.S. Barnard, J. Sharp, J.R. Tong and P.A. Midgley: Science Vol. 313 (2006), p.319.

[9] J.H. Sharp, J.S. Barnard, K. Kaneko, K. Higashida and P.A. Midgley: J. Phys. Conf. Ser. Vol. 126 (2008).

[110] as observed in Fig. 1 and the dislocation line vector was as one indicated in the figure. (b) Calculated local stress intensity factor due to dislocations. z' axis is along the crack front. Mode II component is found to be dominant.

[10] M. Tanaka, K. Higashida, K. Kaneko, S. Hata and M. Mitsuhara: Scripta Mater. Vol. 59 (2008), p.901.

[11] S.S. Ruvimov and K. Scheerschmidt: phy. stat. sol. Vol. (a)141 (1994), p.269.

[12] K. Higashida, N. Narita, R. Onodera, S. Minato and S. Okazaki: Mater. Sci. Eng., A Vol. 237 (1997), p.72.

[13] H. Gao: J. Mech. Phys. Solids Vol. 39 (1991), p.157.

Fetching data from Crossref.
This may take some time to load.