Grain Nucleation and Growth During Phase Transformations

Science ◽  
2002 ◽  
Vol 298 (5595) ◽  
pp. 1003-1005 ◽  
Author(s):  
S. E. Offerman ◽  
N. H. van Dijk ◽  
J. Sietsma ◽  
S. Grigull ◽  
E. M. Lauridsen ◽  
...  
Keyword(s):  
Phase Transformations ◽  
Nucleation And Growth

The influence of water vapor on thermal transformation of boehmite

1992 ◽  
Vol 7 (2) ◽  
pp. 444-449 ◽  
Author(s):  
Zdenek Hrabe ◽  
Sridhar Komarneni ◽  
Ladislav Pach ◽  
Rustum Roy
Keyword(s):  
Water Vapor ◽  
Phase Transformations ◽  
Thermal Transformation ◽  
Nucleation And Growth ◽  
Furnace Atmosphere ◽  
Fast Diffusion ◽  
Thermally Activated ◽  
Activated Processes ◽  
Influence Of Water ◽  
Diffusion Paths

Boehmite compacts and boehmite gels (seeded and unseeded) were annealed at various temperatures in nitrogen and 1 atm water vapor to determine the influence of water vapor on boehmite transformation to new phases, changes in porosity, and morphology. Water vapor was found to accelerate the phase transformations markedly compared to dry N2 treatment. The catalyzing effect of water vapor may be due to its interactions on grain surfaces and generation of fast diffusion paths, resulting in nucleation and growth of new phases. This result shows that control of the furnace atmosphere is a useful variable in thermally activated processes.

Phase Transformation and Densification Behavior of Microwave Sintered γ-A12O3

1994 ◽  
Vol 347 ◽  
Author(s):  
John Freim ◽  
Joanna McKittrick ◽  
Joel Katz ◽  
Kurt Sickafus
Keyword(s):  
Phase Transformation ◽  
Phase Transformations ◽  
Growth Phase ◽  
Particle Morphology ◽  
Nucleation And Growth ◽  
Densification Behavior ◽  
Transformation Behavior ◽  
Gas Condensation ◽  
Grain Sizes ◽  
Dense Bodies

ABSTRACTThe phase transformation and densification behavior of gas condensation synthesized γA12O3 sintered with microwave radiation has been studied. Nucleation and growth phase transformations, which produce α-A12O3 occurred as the material was heated through the temperature range of 800–1300°C. These phase transformations resulted in anomalous grain growth with a distinct change in particle morphology, crystallite size and surface area. A12O3 derived from a chemically synthesized boehmite precursor has been shown to exhibit the same nucleation and growth phase transformation behavior when conventionally heated. It is concluded that nanocrystalline γ or β alumina will not be a viable starting material for the production of dense bodies with grain sizes of less than 100 nm.

scholarly journals A Non-Isokinetic Approach for Modeling Solid-State Transformations: Application to Crystallization of a Fe-B Amorphous Alloy

Materials ◽  
2021 ◽  
Vol 14 (2) ◽  
pp. 292
Author(s):  
Yazhu Ma ◽  
Yubing Zhang ◽  
Feng Liu
Keyword(s):  
Differential Scanning Calorimetry ◽  
Solid State ◽  
Amorphous Alloy ◽  
Phase Transformations ◽  
Kinetic Parameters ◽  
Analytical Model ◽  
Amorphous Alloys ◽  
Nucleation And Growth ◽  
Scanning Calorimetry ◽  
Kinetics Of

Solid-state phase transformations like crystallization of amorphous alloys can be described by an analytical model incorporating a nucleation index a. However, this model cannot be used to examine isochronal transformations with abrupt changing of enthalpy differences performed with differential scanning calorimetry. Based on the model, a non-isokinetic approach is proposed and applied to analyze the isochronal crystallization kinetics of Fe85B15 amorphous alloy. The approach enabled us to obtain the kinetic parameters and activation energies for nucleation and growth.

Sign in / Sign up

Export Citation Format

Share Document