About this Abstract |
Meeting |
2024 TMS Annual Meeting & Exhibition
|
Symposium
|
Defects and Interfaces: Modeling and Experiments
|
Presentation Title |
Grain Boundary Softening from Stress Assisted Helium Cavity Coalescence |
Author(s) |
Jason Trelewicz, Streit Cunningham, Yang Zhang, Spencer Thomas, Osman El-Atwani, Yongqiang Wang |
On-Site Speaker (Planned) |
Jason Trelewicz |
Abstract Scope |
In nanostructured metals containing a high density of interfacial sinks, preferential helium cavity formation on the grain boundaries has been shown to produce softening that is generally attributed to enhanced interfacial plasticity in the presence of gaseous grain boundary defects. In this study, we elucidate the mechanisms responsible for grain boundary softening employing nanoindentation experiments on two grades of helium-implanted ultrafine-grained tungsten with complementary atomistic simulations guided by the experimental results. Collective changes in the mean cavity size, density, and morphology beneath a residual impression on an implanted surface indicate that cavity coalescence accompanied the reduction in hardness. From the atomistic simulations, grain boundary bubble coalescence is shown to be driven by stress concentrations that act to localize strain in the grain boundaries through cooperative deformation processes involving local atomic shuffling and sliding, dislocation emission, and even the nucleation of unstable twinning events. |
Proceedings Inclusion? |
Planned: |
Keywords |
Modeling and Simulation, Nuclear Materials, Mechanical Properties |