Seminar - Gwenaelle Proust - Study and Modeling of the Mechanical Behavior of Hexagonal Metals

Thursday 9 August 2007, 1.10 - 1.50 pm
Civil Engineering Lecture Theatre 3

Gwenaelle Proust
Los Alamos National Laboratory
Post-Doctoral Research Associate

Abstract:
Hexagonal close-packed (hcp) metals deform plastically by a variety of slip and twinning modes. The relative contribution of these mechanisms depends strongly on the material studied and the conditions, such as temperature, under which the deformation is performed. This work further elucidates the complicated competition and interactions between twinning and slip deformation modes for two hcp materials, namely zirconium and magnesium. The model presented here to simulate the mechanical behavior of these materials is a new version of the visco-plastic self consistent (VPSC) model. In this version, twinning is accounted for using a composite-grain twin model which has been shown to better reproduce the effects of the microstructure evolution onto the mechanical response of the material, especially during strain path changes, than previous models. To ensure this microstructure based model is physically accurate, experimental data such as active twinning modes and twin volume fraction evolution are necessary. In this purpose, a new automatic twin recognition code has been developed in order to extract quantitative twin statistics from electron backscattered diffraction (EBSD) data.