Modelling of crystal plasticity effects on the crack initiation energies of a bi-crystal interface (Nb/ A120 3)

Amir Siddiq; Siegfried Schmauder

Amir Siddiq University of Stuttgart
Siegfried Schmauder University of Stuttgart

Abstract

The present paper examines the crystal orientation effects on the energy at the crack-tip of niobium/ alumina joints. The analyses have been done using crystal plasticity theory. The single crystal parameters are identified for each family of slips system in [21]. These identified parameters are being used to examine the orientation effects of the niobium single crystal on the energy at the crack-tip. Differences in the fracture energy are explained based on the plastic slip (strain) induced in different slip systems during deformation. A qualitative comparison of the crystal plasticity analysis with the experiments of [4, 15] is also been presented.

Keywords

crystal plasticity, finite element methods, fracture, metal-ceramic interface,

References

[1] ABAQUS Version 6.4, Hibbitt, Karlsson, Sorensen.
[2] J .L. Bassani, T .-Y. Wu. Latent hardening in single crystals. II: Analytical characterization and predictions. Philos. Trans. Roy. Soc. London A , 435: 21-41, 1991.
[3] W. Brocks, 1. Scheider. Numerical Aspects of the Path-Dependence of the J -Integral in Incremental Plasticity. Technical Note GKSS/WMS/01/08, internal report, 200l.
[4] RM. Cannon, D. Korn, G. Elssner, M. Ruhle. Fracture properties of interfacially doped Nb-Al2O3 bicrystals. II: Relation of interfacial bonding, chemistry and local plasticity. Acta Materialia, 50: 3903- 3925, 2002.
[5] C.P. Cherepanov. Crack propagation in continuous media. Appl. Math. Mech., 31: 476- 488, 1967.