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.

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.

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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