A Mechanism for Particle Coalescence, Grain Growth and Twin Formation During Annealing of Gold Particles in an Amorphous Silica Matrix

1983 ◽  
Vol 21 ◽  
Author(s):  
J. McGinn ◽  
V.A. Greenhut ◽  
T. Tsakalakos
Keyword(s):  
Grain Boundary ◽  
Grain Growth ◽  
Amorphous Silica ◽  
Direct Evidence ◽  
Boundary Migration ◽  
Silica Matrix ◽  
Grain Boundary Migration ◽  
High Angle ◽  
Gold Particles ◽  
Particle Coalescence

ABSTRACTDirect evidence was obtained for the coalescence of discrete gold particles (∼;lO0 nm) surrounded by a continuous amorphous silica matrix during annealing at 900°C. The particles were found to form high angle boundaries as coalescence occurred. Subsequent annealing revealed that grain growth occurred with relatively rapid elimination of high angle grain boundaries. The coalesced particles became approximately spherical in shape and seven particle morphologies could be distinguished. A majority of particles showed either no defect structure or conventional f.c.c. twins. In more limited cases, a small area of high angle grain boundary, usually of coincidence lattice type, was observed which accommodated intersecting twins. A single self-consistent mechanism can explain the elimination of high angle boundaries and all the various twin structures observed. The mechanism is based on Gleiter's [l] model for grain boundary migration with twin structures resulting from growth accidents on the migrating high angle boundary.

Grain boundary migration in small gold particles

1987 ◽  
Vol 192 (2-3) ◽  
pp. L872-L878 ◽  
Author(s):  
Sumio Iijima ◽  
Toshinari Ichihashi
Keyword(s):  
Grain Boundary ◽  
Boundary Migration ◽  
Grain Boundary Migration ◽  
Gold Particles

Microstructure and Mechanical Properties of Mo2FeB2 Based Cermets Containing SiC Whisker

2012 ◽  
Vol 625 ◽  
pp. 304-307 ◽  
Author(s):  
Hai Zhou Yu ◽  
Wen Jun Liu ◽  
Lian Ying ◽  
Min You
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Grain Boundary ◽  
Grain Growth ◽  
Rupture Strength ◽  
Boundary Migration ◽  
Grain Boundary Migration ◽  
Hard Phase ◽  
Maximum Hardness ◽  
Vacuum Sintering

Four series of cermets with the SiC whisker content between 0 and 1.0 wt.% were prepared by vacuum sintering. The transverse rupture strength (TRS), hardness (HRA) and fracture toughness (KIC) were also measured. The SiC whiskeraddition was located at the grain boundaries, which prevented grain boundary migration and restrained the grain growth. However, an increasing SiC whisker content decreased the wettability of the binder on the Mo2FeB2 hard phase. The highest TRS and fracture toughness was found for the cermets with 0.5 wt.% SiC whisker addition, whereas the cermets without SiC whisker addition exhibited the maximum hardness.

Mechanism of Stress-Driven Grain Boundary Migration in Nanotwinned Materials

2018 ◽  
Vol 55 (1) ◽  
pp. 21-25 ◽  
Author(s):  
N.V. Skiba
Keyword(s):  
Theoretical Model ◽  
Grain Boundary ◽  
Twin Boundary ◽  
Boundary Migration ◽  
Grain Boundary Migration ◽  
High Angle ◽  
Twin Boundaries ◽  
Critical Stresses ◽  
Ultrafine Grained ◽  
Ultrafine Grained Materials

Abstract Stress-driven grain boundary (GB) migration in ultrafine-grained materials with nanotwinned structure is theoretically described. In the framework of the theoretical model, the stress-driven high-angle GB migration is accompanied by migration of twin boundaries which adjoin this GB. Energetic characteristics and critical stresses of the GB migration accompanied by the twin boundary migration are calculated.

NORMAL GRAIN GROWTH IN ZONE-REFINED HIGH-PURITY METALS

1959 ◽  
Vol 37 (4) ◽  
pp. 496-498 ◽  
Author(s):  
E. L. Holmes ◽  
W. C. Winegard
Keyword(s):  
Grain Boundary ◽  
Grain Growth ◽  
High Purity ◽  
Liquid State ◽  
Energy Barrier ◽  
Boundary Migration ◽  
Single Atom ◽  
Grain Boundary Migration

Comparisons are made between theoretical and experimental rates of boundary migration during grain growth in zone-refined metals; these indicate that a single-atom process is involved. A model is proposed for the mechanism of grain-boundary migration based on the assumption of a single-atom process and the fact that the energies of activation for grain growth, both in zone-refined lead and tin, are similar to the energy barrier to be overcome by an atom in transferring from the solid to the liquid state during melting.

Solute Drag and Entropy Production - Two Approaches to the Same Phenomenon

2004 ◽  
Vol 467-470 ◽  
pp. 3-10 ◽  
Author(s):  
Mats Hillert
Keyword(s):  
Gibbs Energy ◽  
Grain Boundary ◽  
Phase Transformations ◽  
Entropy Production ◽  
Grain Growth ◽  
Historical Development ◽  
Boundary Migration ◽  
Solute Drag ◽  
Grain Boundary Migration ◽  
Solute Atoms

The historical development of the two approaches to the interaction between solute atoms and a migrating interface, based on dissipation of Gibbs energy and on solute drag, are reviewed and compared. In the way the solute drag was formulated long ago for recrystallization and grain growth, it does not apply to phase transformations. With a new solute drag equation, which was recently proposed, it turns out that the two approaches are completely equivalent for phase transformations as well as grain boundary migration.

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