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Crystal plasticity modeling of fully lamellar titanium aluminide alloys
Citation Link: https://doi.org/10.15480/882.1928
Publikationstyp
Doctoral Thesis
Date Issued
2018
Sprache
English
Author(s)
Advisor
Referee
Title Granting Institution
Technische Universität Hamburg
Place of Title Granting Institution
Hamburg
Examination Date
2018-06-25
TORE-DOI
In the present thesis, a thermomechanically coupled, defect density based crystal plasticity
model is presented. This model accounts for the evolution of dislocation densities and twinned volume fractions on different slip and twinning systems during plastic deformation and thermal recovery. Considering the evolution of dislocation densities and twinned volume fractions allows a physics based formulation of the work hardening model and enables a physically meaningful representation of dissipation and stored energy of cold work in the applied thermomechanical framework. In the course of this thesis, the presented crystal plasticity model was applied to investigate several aspects of the plastic deformation behavior of fully lamellar titanium aluminide alloys. After calibrating the work hardening model to fit experimental results, it was successfully used to relate specifics of the macroscopic stress-strain response of fully lamellar titanium aluminides to the work hardening interactions on the microscale. By combining numerical studies and experimental findings from literature, it was further possible to identify and consequently model the relative contribution of the different coexisting microstructural
interfaces to the macroscopic yield strength. With this microstructure sensitive
model formulation, the influence of the microstructural parameters on the inhomogeneous
microplasticity of fully lamellar titanium aluminides was studied. Due to its defect density
based formulation, the model enabled trends in the static recovery behavior to be investigated. Finally, the model was extended in order to account for the anomalous dependence of the yield strength of fully lamellar titanium aluminides on temperature.
model is presented. This model accounts for the evolution of dislocation densities and twinned volume fractions on different slip and twinning systems during plastic deformation and thermal recovery. Considering the evolution of dislocation densities and twinned volume fractions allows a physics based formulation of the work hardening model and enables a physically meaningful representation of dissipation and stored energy of cold work in the applied thermomechanical framework. In the course of this thesis, the presented crystal plasticity model was applied to investigate several aspects of the plastic deformation behavior of fully lamellar titanium aluminide alloys. After calibrating the work hardening model to fit experimental results, it was successfully used to relate specifics of the macroscopic stress-strain response of fully lamellar titanium aluminides to the work hardening interactions on the microscale. By combining numerical studies and experimental findings from literature, it was further possible to identify and consequently model the relative contribution of the different coexisting microstructural
interfaces to the macroscopic yield strength. With this microstructure sensitive
model formulation, the influence of the microstructural parameters on the inhomogeneous
microplasticity of fully lamellar titanium aluminides was studied. Due to its defect density
based formulation, the model enabled trends in the static recovery behavior to be investigated. Finally, the model was extended in order to account for the anomalous dependence of the yield strength of fully lamellar titanium aluminides on temperature.
Subjects
titanium aluminides
crystal plasticity
micromechanics
DDC Class
600: Technik
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