Microstructure sensitive modeling of deformation behavior of a TiAl alloy with variable lamellae thickness

Abstract

In TiAl alloys the lamellar spacing influences the elastic, plastic, and creep behavior. To predict the alloy behavior a microstructure-sensitive modeling has to be established that is able to capture local plasticity for variable lamellae thickness. The classical micro-mechanical models (e.g., crystal plasticity model) do not contain any structural size-effect; thus, they are not sensitive to the microstructural variation. To overcome this limitation we have introduced intrinsic (material) length scale, as derived from the Tailor dislocation model, in the crystal plasticity constitute behavior. The model allows us to predict local plasticity and global Hall-petch effects as a contribution of statistically stored and geometrically necessary dislocations in the lamellar structures. Based on this model the size-dependency of the lamellar hardening will be presented.