Grain Boundaries, Interfaces, and Surfaces in Ceramics: Fundamental Structure—Property—Performance Relationships: Continuum Approaches
Sponsored by: ACerS Basic Science Division, ACerS Electronics Division
Program Organizers: Rheinheimer Wolfgang, Forschungszentrum Jülich; Catherine Bishop, University of Canterbury; Shen Dillon, University of California, Irvine; Ming Tang, Rice University; John Blendell, Purdue University; Wayne Kaplan, Technion - Israel Institute of Technology; Melissa Santala, Oregon State University
Monday 2:00 PM
October 18, 2021
Room: B244/245
Location: Greater Columbus Convention Center
Session Chair: Wolfgang Rheinheimer, Forschungszentrum Jülich; John Blendell, Purdue University
2:00 PM Invited
Microstructure-within-a-microstructure: Understanding Critical Structural Variations within Grain Boundary Networks: Timothy Rupert1; 1University of California, Irvine
Interfacial engineering has become a powerful tool for manipulating material properties. While evidence continues to mount showing that grain boundary networks are complex entities with many variations in local structure and properties, these variations are not often treated adequately. Here, we discuss the importance of the variety of “microstructure” (fine structural features) contained within one aspect of a traditional microstructure, the interfacial network. Specifically, this talk will discuss the importance of features such as complexion population, network topology, and chemical/structural heterogeneity, using nanocrystalline materials and multi-principal element alloys as model systems to explore these topics. First, we study boundary-to-boundary variations in local chemical composition and complexion type. Next, we investigate unique spatial variations in local structure, such as gradients in short-range order and near-boundary segregation regions. As a whole, our results emphasize that interfacial networks are complicated entities, with renewed efforts needed to identify, characterize, and understand the finer details.
2:40 PM Invited
Elucidating Grain Boundary Motion with 4D Grain Growth Measurements Using Non-destructive X-ray Diffraction Grain Mapping: Amanda Krause1; 1University of Florida
Several similar x-ray diffraction-based techniques that non-destructively characterize the 3D microstructure, including grain orientation and grain boundary location, have been developed and made more accessible over the past decade. These non-destructive grain mapping techniques provide a unique perspective of grain boundary motion in 3D microstructures because the same boundaries can be tracked before and after a heat treatment. Such 4D studies allow us to test accepted grain growth theories, e.g. influence of local curvature on grain boundary motion, and probe previously unexplained phenomenon like anti-thermal grain growth in SrTiO3. The method has a particular advantage of exploring anisotropic grain boundary behavior in 3D microstructures. Here, relationships between grain boundary velocity, character and energy are explored with high energy x-ray diffraction microscopy and laboratory-based diffraction contrast tomography measurements of ceramic materials. The challenges associated with these technique will also be discussed.
3:20 PM Break
3:40 PM
Effect of Sodium on the Processability and Mechanical Properties of Nanocrystalline
Magnesium Aluminate: Isabella Loureiro Muller Costa1; Ricardo Castro1; Joice Miagava2; 1University of California Davis; 2Insper – Institute of Education and Research
The undesirable grain coarsening that nanocrystalline ceramics experiences, when exposed to high temperatures, due to their excess grain boundary (GB) energy, can be controlled through the segregation of dopants to the GB. Nanocrystalline materials with higher GB stability have displayed a postponed Hall-Petch breakdown. Recent reports have related an increase in the local toughness of nanoceramics to the more homogenous energetic landscape across the GB experienced with the dopant segregation. In this work, we describe the role of sodium (Na) as a dopant in magnesium aluminate (MAO) which is of great interest for sensor array compartment. The pellets were sintered by spark plasma sintering; the effect of sodium content on the processability, hardness, and toughness of MAO were evaluated. Translucent pellets were obtained with concentrations as high as 10.9mol% of Na. The increase in the dopant content led to a decrease in the sintering pressure and an increase in hardness.