Cleavage due to dislocation confinement in layered materials

@article{citeulike:763442, abstract = {of dislocation confinement on fracture behavior in laminates consisting of alternating submicron ductile and brittle layers are studied. When the ductile layer thickness is below the micron level, dislocations must be treated individually. Dislocations emitted from the crack tip have two effects: they blunt the crack and thereby reduce the tensile stress at the crack tip ; and pile up against an interface and send a back stress to the crack tip to hinder further dislocation emission. Consequently, an equilibrium number of dislocations exists at a given load level. We estimate this number by considering the stability conditions for dislocations threading in the ductile layer, and dislocation pile-up is treated as an equivalent superdislocation. Furthermore, the competition between further dislocation emission and cleavage at the blunted crack tip is considered. Our result shows that because of the confinement, as the applied load increases, the tensile stress at the blunted crack tip also increases. Cleavage occurs when the tensile stress at the crack tip reaches the theoretical strength. Given a sufficiently thin constraining layer, cleavage can even occur in ductile metals such as copper and aluminum. The implications of this model for several material systems are discussed.}, author = {Hsia, K. J. and Suo, Z. and Yang, W. }, citeulike-article-id = {763442}, doi = {http://dx.doi.org/10.1016/0022-5096(94)90076-0}, journal = {Journal of the Mechanics and Physics of Solids}, keywords = {dislocation, layer}, month = {June}, number = {6}, pages = {877--896}, posted-at = {2006-07-18 21:17:04}, priority = {2}, title = {Cleavage due to dislocation confinement in layered materials}, url = {http://dx.doi.org/10.1016/0022-5096(94)90076-0}, volume = {42}, year = {1994} }

TY - JOUR ID - citeulike:763442 L3 - citeulike-article-id:763442 TI - Cleavage due to dislocation confinement in layered materials JF - Journal of the Mechanics and Physics of Solids VL - 42 IS - 6 SP - 877 EP - 896 N2 - of dislocation confinement on fracture behavior in laminates consisting of alternating submicron ductile and brittle layers are studied. When the ductile layer thickness is below the micron level, dislocations must be treated individually. Dislocations emitted from the crack tip have two effects: they blunt the crack and thereby reduce the tensile stress at the crack tip ; and pile up against an interface and send a back stress to the crack tip to hinder further dislocation emission. Consequently, an equilibrium number of dislocations exists at a given load level. We estimate this number by considering the stability conditions for dislocations threading in the ductile layer, and dislocation pile-up is treated as an equivalent superdislocation. Furthermore, the competition between further dislocation emission and cleavage at the blunted crack tip is considered. Our result shows that because of the confinement, as the applied load increases, the tensile stress at the blunted crack tip also increases. Cleavage occurs when the tensile stress at the crack tip reaches the theoretical strength. Given a sufficiently thin constraining layer, cleavage can even occur in ductile metals such as copper and aluminum. The implications of this model for several material systems are discussed. KW - dislocation KW - layer AU - Hsia, KJ AU - Suo, Z AU - Yang, W PY - 1994/06// UR - http://dx.doi.org/10.1016/0022-5096(94)90076-0 ER -