Enhanced Stability and Mechanics of Ultra-fine Grained Metals via Engineered Solute Segregation
Abstract
This one-year project supported one graduate student and led to the following milestones: A) Impurity Effects on Morphological Stability of Recrystallization Fronts: We investigates the origin of serrations during motion of recrystallization fronts. Past experiments have attributed the morphologies to the variations in the stored energy of deformation. The role of impurities has been ignored, although past studies have shown that front properties are dramatically altered by trace amounts of impurities. Here, we employ a combination of theoretical frameworks, Ising and molecular dynamics to study the influence of impurities on the stability of a moving recrystallization front, as determined by the balance between stored energy of deformation, solute drag and boundary stiffness. A linear stability analysis shows that the instability is enhanced at small impurity concentrations, and it is sensitive to the kinetics of impurities along and normal to the boundary. Our results underline the role of both driving forces and impurity diffusivities on the morphological stability of recrystallization fronts. In particular, the findings underscore the importance of solutes destabilizing recrystallization fronts in dilute alloys. The findings were presented at a TMS Annual meeting, and will be followed by a peer-reviewed publication in this coming year. B) Random Walk of a Solute Loaded fluctuating grain Boundary: Tailoring the solute segregation at extended defects such as dislocations and interfaces is critical for engineering crystalline materials. Here, we use a combination of theoretical analyses and numerical simulations to study the effect of segregation on equilibrium fluctuations of grain boundaries. The random walk of the dirty interface occurs within a confining solute cloud that itself evolvesstochastically in the crystalline matrix, albeit at a much slower rate. The coupled response, a random walk within a random walk, represents a new class of stochastic dynamics.
Document Details
- Document Type
- Technical Report
- Publication Date
- Aug 17, 2017
- Accession Number
- AD1068238
Entities
People
- Moneesh Upmanyu
Organizations
- Northeastern University