Final Report for ARO sponsored research (ARO-W911NF-12-1-05869)
Abstract
Residual stress plays in important role in mechanical properties of polycrystalline materials, including deformation, fracture, corrosion and fatigue, etc. The effects become more significant when the grain size reaches nanometer scales where the local stress level could reach gigapascal. Residual stress in polycrystalline materials with grain size of microns or larger can be acquired via x-ray or neutron scattering, in conjunction with finite element continuum modeling. Below a few hundred nanometers, however, these methods fail. How to obtain residual stresses at these small scales remains an open issue. A more challenge issue is how to obtain residual stresses associate with different microstructural components, such as each grain boundary, triple junction line, or a grain, which have even smaller length scales, usually at angstrom or less than a nanometer. This question is critical to understanding the effects of the residual stress on material properties in a quantitative fashion. As far as we know, there is no prior work on this topic. As a result, few results are available for the local information in polycrystalline materials. The purpose of this work is to connect the mechanical properties of nanocrystalline Mg and Mg alloys to the residual stresses and furthermore, determine quantitatively the residual stress in nanocrystalline Mg, Mg alloys and other hcp metals. This work is of particular importance since hcp metals and alloys are known to have strong structural and mechanical anisotropy. They tend to form textures which make their mechanical properties strongly susceptible to internal stress and vice versa. Our goal in this work is therefore to quantitatively determine the internal stress and link the internal stress to microstructural components such as grain boundaries, triple junctions, and grains to residual stresses. Therefore, quantitative relations between the microstructures and mechanical properties can be established via residual stress.
Document Details
- Document Type
- Technical Report
- Publication Date
- Dec 23, 2013
- Accession Number
- AD1063193
Entities
People
- Mo Li
Organizations
- Georgia Tech Research Corporation