THIS GRANT IS A CONTINUATION OF N00014-14-1-0530 Mechanistic Regimes of Grain-Boundary Anion and Cation Diffusion in Alumina
Abstract
These funds are for Dr. Martin Harmer. Drs. Helen Chan and Jeff Rickman also of Lehigh University will be co-investigators on this project. The aim of this proposal is to extend our previous investigations of the role of reactive elements on grain-boundary diffusion in doped alumina to identify clearly distinct kinetic regimes. This program is both experimental and computational in nature, involving novel oxidation experiments with Ni marker particles, electron microscopy and numerical modeling, and will encompass several interrelatedthrusts. First, building on our findings from oxidation experiments, we will examine the impact of doping on both anion and cation grain-boundary diffusion in alumina for a variety of dopants. From the dependence of the oxidation rate on dopant concentration, we will elucidate the mechanism for boundary diffusion as a function of dopant size and charge. Finally, we will explore the possibility that grain-boundary transitions may alter the mechanism for anion diffusion for temperatures below about 1300 degC. Such transitions may alter boundary chemistry and structure, with concomitant changes in boundary kinetics. This thrust will involve both oxidation experiments at low temperatures and complementary numerical modeling of grain-boundary diffusion in polycrystals. The goal will be to extract useful information regarding activation energies from Arrhenius plots that relate the diffusivity of the system to temperature.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Aug 12, 2016
- Source ID
- N000141612701
Entities
People
- Martin P Harmer
Organizations
- Lehigh University
- Office of Naval Research
- United States Navy