13 research outputs found
Solute Segregation in a Moving Grain Boundary: A Novel Phase-Field Approach
We present a novel phase-field approach for investigating solute segregation
in a moving grain boundary. In our model, the correct choice of various
parameters can control the solute-grain boundary interaction potential,
resulting in various segregation profiles that agree with Cahn solute drag
theory. Furthermore, we explore how different segregation profiles evolve at
varying GB velocities owing to the inequality of the atomic flux of solute
between the front and back faces of the moving grain boundary. We highlight
velocity variations among segregation profiles in low and high-velocity
regimes. This model reveals how grain boundary segregation affects grain
growth, providing insights for future alloy desig
2mech: a Software Package Combining Microstructure Modeling and Mechanical Property Prediction
We have developed a graphical user interface (GUI) based package 2mech
to perform phase-field simulation for predicting microstructure evolution. The
package can take inputs from ab initio calculations and CALPHAD (Calculation of
Phase Diagrams) tools for quantitative microstructure prediction. The package
also provides a seamless connection to transfer output from the mesoscale phase
field method to the microscale finite element analysis for mechanical property
prediction. Such a multiscale simulation package can facilitate
microstructure-property correlation, one of the cornerstones in accelerated
materials development within the integrated computational materials engineering
(ICME) framework
Edge Stabilities of Hexagonal Boron Nitride Nanoribbons: A First-Principles Study
We investigate the comparative stability of sp(2) bonded planar hexagonal boron nitride (h-BN) nanoribbon (BNNR) edges, using first principles calculations. We find that the pristine armchair edges have the highest degree of stability. Pristine zigzag edges are metastable, favoring planar reconstructions in the form of 5-7 rings] that minimizes the energy. Our investigation further reveals that the pristine zigzag edges can be stabilized against 5-7 reconstructions by passivating the dangling bonds at the edges by other elements, such as hydrogen (H) atoms. Electronic and magnetic properties of nanoribbons depend on the edge shapes and are strongly affected by edge reconstructions
Thermal stability of spherical nanoporous aggregates and formation of hollow structures by sintering—a phase-field study
Nanoporous structures are widely used for many applications and hence it is important to investigate their thermal stability. We study the stability of spherical nanoporous aggregates using phase-field simulations that explore systematically the effect of grain boundary diffusion, surface diffusion, and grain boundary mobility on the pathways for microstructural evolution. Our simulations for different combinations of surface and GB diffusivity and GB mobility show four distinct microstructural pathways en route to 100% density: multiple closed pores, hollow shells, hollow shells with a core, and multiple interconnected pores. The microstructures from our simulations are consistent with experimental observations in several different systems. Our results have important implications for rational synthesis of hollow nanostructures or aggregates with open pores, and for controlling the stability of nanoporous aggregates that are widely used for many applications