ATOMISTIC SIMULATIONS OF DIFFUSIONAL CREEP IN A NANOCRYSTALLINE BODY-CENTERED CUBIC MATERIAL
Molecular dynamics (MD) simulations are used to study diffusion-accommodated creep deformation in nanocrystalline molybdenum, a body-centered cubic metal. In our simulations, the microstructures are subjected to constant-stress loading at levels below the dislocation nucleation threshold and at high temperatures (i.e., T > 0.75Tmelt), thereby ensuring that the overall deformation is indeed attributable to atomic self-diffusion. The initial microstructures were designed to consist of hexagonally shaped columnar grains bounded by high-energy asymmetric tilt grain boundaries (GBs). Remarkably the creep rates, which exhibit a double-exponential dependence on temperature and a double power-law dependence on grain size, indicate that both GB diffusion in the form of Coble creep and lattice diffusion in the form of Nabarro–Herring creep contribute to the overall deformation. For the first time in an MD simulation, we observe the formation and emission of vacancies from high-angle GBs into the grain interiors, thus enabling bulk diffusion.
- Research Organization:
- Idaho National Laboratory (INL)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- AC07-99ID13727
- OSTI ID:
- 935788
- Report Number(s):
- INL/JOU-07-12518
- Journal Information:
- Acta Materialia, Journal Name: Acta Materialia Journal Issue: 14 Vol. 56; ISSN 1359-6454; ISSN ACMAFD
- Country of Publication:
- United States
- Language:
- English
Similar Records
Grain-boundary diffusion creep in nanocrystalline palladium by molecular-dynamics simulation.
Is diffusion creep the cause for the inverse Hall-Petch effect in nanocrystalline materials?