Restricted Research - Award List, Note/Discussion Page

Fiscal Year: 2021

223  University of North Texas  (84519)

Principal Investigator: Srivilliputhur,Srinivasan G

Total Amount of Contract, Award, or Gift (Annual before 2011): $ 200,000

Exceeds $250,000 (Is it flagged?): No

Start and End Dates: - 6/21/23

Restricted Research: YES

Academic Discipline: Materials Science & Engineer

Department, Center, School, or Institute: College of Engineering

Title of Contract, Award, or Gift: An Atomic Bonding Informed Approach to Rewrite the Rules of Solid-Solution and Precipitation Strengthening

Name of Granting or Contracting Agency/Entity: Air Force Office of Scientific Research
CFDA Link: DOD
12.800

Program Title: N/A
CFDA Linked: Air Force Defense Research Sciences Program

Note:

Classical solid solution and precipitation strengthening models in alloys are indispensible for quantifying the overall balance of mechanical properties. However, such models do not include the influence of local electronic structure and atomic bonding between solute and solvent atoms as well as across precipitate/matrix interfaces. Thus, they also ignore the consequent short-range solute-solute and solute- solvent interactions, which if covalent in character will significantly increase the local (as opposed to bulk) stiffness of the material, and strongly influence how microstructural defects interact with solutes. Our extensive density functional theory (DFT) based calculations have clearly demonstrated that such localized bonding character, identified by the anisotropic localization of valence electron density along specific crystallographic directions, affect phase stability, the nature of precipitate/matrix interfaces, and defect processes driving deformation. Those studies beg a fundamental question – How will such localized directional bond character influence solid solution and precipitation strengthening? We answer this question through the study of two model alloys – a substitutional Ti binary alloy and an intermetallic Ni3Al intermetallic with a ternary solute substitution – that have well-known strengthening models based on size and modulus mismatch between the constituent solute and solvent atoms. Our proposal’s four thrust areas couple experiments with DFT and large-scale semi-empirical molecular dynamics (MD) simulations to (1) validate and quantify covalent-like bond character in solid solutions and intermetallics, (2) create DFT validated semi-empirical interatomic potential framework that incorporate solute atom induced changes to the shape of local electron densities, and (3) utilize these new potentials in large-scale MD simulations to systematically study the effect of such directional bonding on alloy deformation. The overall goal is to closely integrate computation and experiments to create faithful, physics-informed solid solution and precipitation strengthening models, with the computations guiding the experiments, framed in the Materials Genome Initiative (MGI)/Integrated Computational Materials Engineering (ICME) philosophy.

Discussion: No discussion notes

 

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