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Lecture

WEB Analysis of stress-enhanced diffusion in the vicinity of dislocations

Wednesday (23.09.2020)
10:40 - 10:55 M: Modelling and Simulation 1
Part of:


Dislocations are known as paths of high diffusivity for a broad range of materials, for example in metals. For ceramic materials, the impact of dislocations on ionic transport is still disputed since space charge zones can effectively block transport of ions through the material.

One factor that has not found attention so far are the mechanical stresses in a dislocation's vicinity. These have been shown to significantly affect the solid-state diffusion through drift [1,2] and through modification of energy barriers [3]. However, current approaches for modeling the correlation between dislocations and diffusion focus on the segregation of impurities along the dislocation line. The effect of stresses on diffusion is addressed only in a simplified manner, if at all.

In this work we analyze the relationship between dislocation-induced stress fields and local diffusivity by means of continuum models and finite-element-simulation. The dislocation is thereby modeled as an distributed eigenstrain in order to obtain nonsingular stress fields [4]. Stress-driven diffusion effects are regarded through a coupled diffusion model which acts as a basis for the derivation of a material sample's effective diffusivity due to the presence of dislocations.


References:

[1] P. Stein, Y. Zhao, and B.-X. Xu, J. Power Sources 332 (2016) 154–169. DOI: doi.org 10.1016/j.jpowsour.2016.09.085

[2] P. Stein, B.-X. Xu, Comput. Methods Appl. Mech. Engrg. 268 (2014) 25–244. DOI: doi.org/10.1016/j.cma.2013.09.011

[3] P. Stein et al., Acta Materialia 159 (2018) 225-240, DOI: doi.org/10.1016/j.actamat.2018.07.046

[4] W.Cai et al., J. Mech. Phys. Solids 54 (2006) 561-587. DOI: doi.org/10.1016/j.jmps.2005.09.005

Speaker:
Christoph Reimuth
Technische Universität Darmstadt
Additional Authors:
  • Dr. Peter Stein
    Technische Universität Darmstadt
  • Prof. Dr. Bai-Xiang Xu
    Technische Universität Darmstadt