Plastic strain localization in relation with microstructure in titanium alloys – PLASLOTI

Cutting edge experimental techniques will be employed to address this issue. Firstly, deformation mechanisms will be analyzed using digital image correlation with a high spatial resolution. This study will involve micrographs captured using a scanning electron microscope to extract the characteristics of deformation at the microstructure scale. The operating slip systems and the slip amplitude will be key information. Secondly, interactions between slip activity and grain boundaries will be examined using transmission electron microscopy. More specifically, scanning electron microsopy based characterization will be applied to rationalize the findings extracted from digital image correlation data.

To this date, experimental procedures have been defined and validated to collect data required for the analysis of slip localization in relation to microstructure. This includes microstructure characterization, mechanical properties, kinematical fields and imaging of dislocation structures in specific locations.

This approach will allow an improved understanding of interactions between plasticity and microstructure at the mesoscale. This topic is of critical importance to improve the prediction of mechanical properties such as fatigue. In addition, the data will be valuable inputs for crystal plasticity models enhanced with a physical description of the role of interfaces in the deformation behavior. This will be very useful in the context of recent development of models including an improved simulation of interactions between plasticity and interfaces.

Recent findings have been presented at the congrès francais de mécanique 2023 conference:
Etude de la plasticité à l’échelle de la microstructure dans le Ti-6Al-4V, T. Yvinec, V. Valle, S. Hémery, CFM 2022 (poster)

The understanding of the relation between microstructure and plastic deformation is critical to improve the performance of titanium alloys for in service conditions. In this project, plastic strain localization with an emphasis on interactions between slip bands and grain boundaries will be investigated with a statistical representativity in order to improve predictability of the occurrence of deformation processes. In particular, a PhD student will work to improve the understanding of deformation processes using a recently developed digital image correlation technique (H-DIC) to quantify mechanical fields at the sub-grain scale. Further information on operating deformation processes and mechanisms will be obtained through a fine scale analysis of deformation mechanisms using transmission imaging of regions of interest in a scanning electron microscope. Usage of these novel techniques will be allowed by the participation of V. Valle, who is professor and has developed the H-DIC method, and F. Hamon, who is engineer in charge of electron microscopy in Institut Pprime. The simultaneous knowledge of active deformation mechanisms and mechanical fields will allow to improve the understanding of the competition between different deformation processes and opens insights into enhanced prediction capabilities.