The selection of grain-growth control additives for the sintering of ceramics

1970 ◽  
Vol 37 (291) ◽  
pp. 833-838 ◽  
Author(s):  
D. W. Budworth
Keyword(s):  
Grain Boundary ◽  
Grain Growth ◽  
Growth Control ◽  
Boundary Films ◽  
Selection Of

SummaryThe close interrelation between sintering and grain growth is discussed critically, and the necessity for control, but not suppression, of grain growth is established. A distinction between discontinuous and exaggerated grain growth is drawn, and the superiority of grain boundary films as grain-growth control agents is demonstrated. Work on the establishment of tentative criteria for the selection of grain-growth control additives for alumina is reviewed and discussed, and the extension of these ideas to the selection of NaF as a successful aid for magnesia is described.

scholarly journals An Investigation on Grain Growth in a Commercial Al–Mg Alloy

1998 ◽  
Vol 30 (3-4) ◽  
pp. 191-206 ◽  
Author(s):  
I. Samajdar ◽  
L. Rabet ◽  
B. Verlinden ◽  
P. Van Houtte
Keyword(s):  
Grain Size ◽  
Grain Boundary ◽  
Grain Growth ◽  
Primary Recrystallization ◽  
Abnormal Grain Growth ◽  
Grain Boundary Character Distribution ◽  
Grain Boundary Character ◽  
Character Distribution ◽  
Boundary Character Distribution ◽  
Selection Of

Alloy AA5182 contains coarse constituent particles and submicron dispersoids. While the former may cause particle stimulated nucleation (PSN) during primary recrystallization, the fine dispersoids may ‘arrest’ grain growth during subsequent annealing. Abnormal grain growth was observed after dissolution/coarsening of the dispersoids. Mainly S [{123}〈634〉] grains, but also some Brass [{011}〈112〉] and Cu [{112}〈111〉] grains, were observed to grow abnormally. Both the grain size and the grain boundary character distribution (GBCD) possibly played a role in the selection of the grains for abnormal grain growth. A dramatic increase in the number fraction of extremely low angle (1−5°) boundaries was observed with annealing, the increase being more at 470°C (when dispersoids were stable and grain growth was arrested more effectively) than at 500°C/530°C (when inhibition to grain growth was less). The nature of the CSL boundaries did not change significantly with annealing time/temperature.

scholarly journals Controlling sintering and grain growth of nanoceramics

Cerâmica ◽  
2019 ◽  
Vol 65 (373) ◽  
pp. 122-129 ◽  
Author(s):  
R. H. R. Castro
Keyword(s):  
Grain Boundary ◽  
Grain Growth ◽  
Growth Control ◽  
Interfacial Area ◽  
Ceramic Processing ◽  
Sintering Aids ◽  
Parameter Choice ◽  
Grain Boundary Mobility ◽  
Interfacial Energies ◽  
Diffusion Paths

Abstract Sintering and grain growth are fundamental processes affecting microstructural evolution of ceramics. The phenomenological models describing these processes as found in textbooks are simplifications of the very dynamic set of system’s parameters, which lead to limited predictability and the need for extensive empirical analyses for process optimization. One such simplification is the underestimation of interfacial energies and their relationships with diffusion paths and growth control. The goal of this paper is to clarify how thermodynamics of interfaces can provide opportunities for a more refined control of ceramic processing. On the first part of this paper we discuss the relevance of grain boundary energies in grain growth, showing that although grain boundary mobility is the preferred parameter choice for designing of grain growth inhibition, recent studies demonstrate dopants can be selected to annihilate the process driving force and enable thermally (meta)stable nanoceramics. In the second part of the paper, we point out shortcomings from the current sintering theory and discuss that both surface and grain boundary energies with their associated rates of interfacial area evolution represent a more comprehensive sintering description. This perspective offers tunable parameters that may set a new foundation for the design of sintering aids for optimal densification.

Diethylammonium Iodide Assisted Grain Growth with Sub‐Grain Cluster to Passivate Grain Boundary for CH 3 NH 3 PbI 3 Perovskite Solar Cells

2020 ◽  
Vol 8 (10) ◽  
pp. 2000412
Author(s):  
Lan Xiao ◽  
Zhengchun Wang ◽  
Tong Wu ◽  
Pingli Qin ◽  
Xueli Yu ◽  
...  
Keyword(s):  
Solar Cells ◽  
Grain Boundary ◽  
Grain Growth ◽  
Perovskite Solar Cells

Grain Boundary Films in Boron Steels

JOM ◽  
1953 ◽  
Vol 5 (3) ◽  
pp. 445-446
Author(s):  
J. W. Spretnak ◽  
Rudolph Speiser
Keyword(s):  
Grain Boundary ◽  
Boundary Films ◽  
Boron Steels

Texture and Ductility of Ni3Al Foils

2011 ◽  
Vol 306-307 ◽  
pp. 116-119
Author(s):  
Masahiko Demura ◽  
Ya Xu ◽  
Toshiyuki Hirano
Keyword(s):  
Grain Boundary ◽  
Grain Growth ◽  
Memory Effect ◽  
Texture Evolution ◽  
High Mobility ◽  
Two Stage ◽  
Texture Memory ◽  
Highly Effective ◽  
Cold Rolled

This article presents the texture evolution and the ductility improvement of the cold-rolled foils of boron-free Ni3Al during the recrystallization and the subsequent grain growth. The cold-rolled foils had sharp {110} textures. After the recrystallization at 873K/0.5h, the texture was disintegrated with several texture components. Interestingly, most of them had a single rotation relationship. i.e. 40˚ around <111>. With the progress of the grain growth, however, the texture returned to the sharp, cold-rolled textures. This two-stage texture evolution, called as “Texture memory effect”, was explained assuming a high mobility of the grain boundary with the 40˚<111> rotation relationship. The texture returning was highly effective to improve the ductility of the foils.

Fracture Strengths of Individual Grain Boundaries in Ni3Ai Using a Miniaturized Disk Bend Test

1991 ◽  
Vol 238 ◽  
Author(s):  
Douglas E. Meyers ◽  
Alan J. Ardell
Keyword(s):  
Plastic Deformation ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Grain Growth ◽  
Coincident Site Lattice ◽  
Bend Test ◽  
High Angle ◽  
Load Drop ◽  
Site Lattice ◽  
Special Boundaries

ABSTRACTThe results of our initial efforts at measuring the fracture strengths of grain boundaries In Ni3Al using a miniaturized disk-bend test are presented. The samples tested were 3 mm in diameter and between 150 and 300 μm thick. An Ingot of directlonally-solidlfled, boron-free Ni3Al containing 24% Al was annealed between 1300 and 1350 °C to induce grain growth, producing many grain boundaries In excess of 1.5 mm in length. Specimens were cut from these In such a way that one long grain boundary was located near a diameter of the specimen. The relative orientations of the grains on either side of the boundary were determined from electron channeling patterns. Low-angle boundaries are so strong they do not fracture; Instead the samples deform In a completely ductile manner. High-angle boundaries always fracture, but only after considerable plastic deformation of the two grains flanking them. Fracture is Indicated by a load drop in the load vs. displacement curves. A method involving extrapolation of the elastic portion of these curves to the displacement at fracture is used to estimate the fracture stresses. This procedure yields consistent values of the fracture strengths of high-angle boundaries. The measured stresses are large (∼2 to 3 GPa), but considerably smaller than those required for the fracture of special boundaries, as predicted by computer simulations. No correlation was found between the fracture stresses or loads and the geometry of the high-angle boundaries, many of which are close to, but deviate from, coincident site lattice orientations.

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