Tilt Grain Boundaries In Copper Research Articles

Crack direction effects along copper/sapphire interfaces

The Rice-Thomson model is used to predict the directional toughness of a copper/sapphire interface, consisting of a {221} face of a copper crystal bonded to a basal sapphire surface. Specimens of this type are subsequently tested, in the form of a layered beam (having two opposing cracking directions) subject to four-point bending and confirm the theoretical predictions. A general observation is that the ductile or brittle response of a crack on a metal/ceramic interface is strongly dependent on the relative orientation of available slip planes to the existing crack plane and growth direction. This conclusion is consistent with earlier results by Wand and Anderson on symmetric tilt grain boundaries in copper and explains, for example, why brittle cracking occurs in the [ 1 14 ] direction along the {221} interface of a tensile-loaded copper bicrystal, but along the opposite [ 114 ] direction in bending-loaded copper/sapphire specimens with mixed mode conditions at the crack tips.

Misorientation effects upon diffusion induced grain boundary migration in the copper-zinc system

Diffusion induced grain boundary migration has been studied as a function of misorientation. using initially symmetrical tilt grain boundaries in copper exposed to zinc vapor. The migration rate, solute penetration depth and the zinc concentration in the wake of the boundary are all strongly dependent on the grain boundary parameters. The studied processes occur at much lower rates when the diffusion direction is across rather than along the tilt axis, but the dependence upon misorientation persists. The morphology of the alloyed material also depends upon the initial grain boundary misorientation, and we present some data concerning the distribution of solute developed by the process.