|About this Abstract
||2016 TMS Annual Meeting & Exhibition
||Mechanical Behavior at the Nanoscale III
||W-16: Micromechanisms Governing Plastic Instability in Al-Li based Alloys
||Henry Ovri, Eric A Jägle, Andreas Stark, Erica T Lilleodden
|On-Site Speaker (Planned)
Plastic instability limits formability and promotes formation of surface striations during forming processes. While the origin of this phenomenon in solution strengthened Al alloys has been traced to dynamic solute aging of both mobile and forest dislocations by solute atoms, it is yet unclear which microscopic mechanism(s) govern it in precipitation strengthened Al-Li alloys. In this work, nanomechanical testing was used to investigate plastic instability in Al-Li alloys; nanoindentation-based strain rate jump tests reveal the negative strain rate sensitivity typical for this class of plastic instability, while in situ tensile straining in the TEM was able to uniquely identify order hardening as the governing strengthening mechanism. Together with supporting high resolution microstructural characterization, these observations led to the development of a mechanistic model of plastic instability in Al-Li alloys, highlighting the effectiveness of nanoscale mechanical testing in the study of the underlying mechanisms responsible for macroscale response in bulk metals.
||Planned: A print-only volume