Crack-like grain-boundary diffusion wedges in thin metal films

✍ Scribed by H. Gao; L. Zhang; W.D. Nix; C.V. Thompson; E. Arzt

• Book ID: 104403918
• Publisher: Elsevier Science
• Year: 1999
• Tongue: English
• Weight: 266 KB
• Volume: 47
• Category: Article
• ISSN: 1359-6454
• DOI: 10.1016/s1359-6454(99)00178-0

✦ Synopsis

AbstractÐConstrained grain-boundary diusion in polycrystalline thin metal ®lms on substrates is studied as a strongly coupled elasticity and grain-boundary diusion problem in which no sliding and no diusion are allowed at the ®lm/substrate interface. Surface diusion and grain-boundary grooving are neglected in the present analysis. We show that such a diusion process leads to the formation of crack-like grainboundary wedges which cause the normal traction along the grain boundary to decay exponentially with time. A rigorous mathematical analysis is performed to derive and calculate the transient solutions for diffusion along a single grain boundary and along a periodic array of grain boundaries. An approximate closed-form solution is also given as a simple description of constrained grain-boundary diusion. A most remarkable feature of the solution is that the diusion wedges induce crack-like singular stress concentrations which could also enhance dislocation plasticity processes in a metal ®lm.