scholarly journals A study on the effect of the number of clusters at the phase transformation kinetics

2021 ◽  
Author(s):  
Nathan Fernandes Ignácio ◽  
Maisa Silva Fernandes ◽  
Diego Magalhães Baía ◽  
Ana Gabriela Conceição dos Santos ◽  
Felipe da Silva Siqueira ◽  
...  
Keyword(s):  
Phase Transformation ◽  
Transformation Kinetics ◽  
Number Of Clusters ◽  
Phase Transformation Kinetics

scholarly journals Solid state phase transformation kinetics in Zr-base alloys

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
A. R. Massih ◽  
Lars O. Jernkvist
Keyword(s):  
Phase Transformation ◽  
Solid State ◽  
Zirconium Alloys ◽  
Excess Oxygen ◽  
Transformation Kinetics ◽  
Fuel Cladding ◽  
Reactor Accident ◽  
Phase Transformation Kinetics ◽  
Solid State Phase Transformation ◽  
Water Reactors

AbstractWe present a kinetic model for solid state phase transformation ($$\alpha \rightleftharpoons \beta$$ α ⇌ β ) of common zirconium alloys used as fuel cladding material in light water reactors. The model computes the relative amounts of $$\beta$$ β or $$\alpha$$ α phase fraction as a function of time or temperature in the alloys. The model accounts for the influence of excess oxygen (due to oxidation) and hydrogen concentration (due to hydrogen pickup) on phase transformation kinetics. Two variants of the model denoted by A and B are presented. Model A is suitable for simulation of laboratory experiments in which the heating/cooling rate is constant and is prescribed. Model B is more generic. We compare the results of our model computations, for both A and B variants, with accessible experimental data reported in the literature covering heating/cooling rates of up to 100 K/s. The results of our comparison are satisfactory, especially for model A. Our model B is intended for implementation in fuel rod behavior computer programs, applicable to a reactor accident situation, in which the Zr-based fuel cladding may go through $$\alpha \rightleftharpoons \beta$$ α ⇌ β phase transformation.

scholarly journals Phase transformation kinetics of zirconium under ramp wave loading with different windows

2018 ◽  
Vol 67 (7) ◽  
pp. 070204
Author(s):  
Chong Tao ◽  
Wang Gui-Ji ◽  
Tan Fu-Li ◽  
Zhao Jian-Heng ◽  
Tang Zhi-Ping
Keyword(s):  
Phase Transformation ◽  
Wave Loading ◽  
Transformation Kinetics ◽  
Phase Transformation Kinetics ◽  
Kinetics Of

Nb-H Thin Films: On Phase Transformation Kinetics

2017 ◽  
Vol 371 ◽  
pp. 160-165
Author(s):  
Vladimir Burlaka ◽  
Kai Nörthemann ◽  
Astrid Pundt
Keyword(s):  
Thin Films ◽  
Phase Transformation ◽  
Scanning Tunneling ◽  
State Change ◽  
Transformation Kinetics ◽  
Tunneling Microscopy ◽  
Fast Phase ◽  
Phase Transformation Kinetics ◽  
Local Lattice ◽  
The Impact

It was recently shown that phases forming in thin films undergo a coherency state change depending on the film thickness. For Nb-H thin films, the coherency state was reported to change at about 38 nm. In this study the impact of the coherency state on the phase transformation kinetics is investigated for Nb films of two different film thicknesses (25 nm and 80 nm), below and above the state change thickness. The phase transformation in thin metal-hydrogen films can be studied by surface topography analyses via scanning tunneling microscopy (STM) because of the strong local lattice expansion of the hydride precipitates. STM on Nb-H reveals fast phase transformation kinetics for the 25 nm Nb-film, and much slower kinetics for the 80 nm film. This is suggested to be related to the change in the coherency between the Nb-matrix and the hydride precipitates.

Phase transformation kinetics during continuous heating of a β-quenched Ti–10V–2Fe–3Al alloy

2014 ◽  
Vol 50 (3) ◽  
pp. 1412-1426 ◽  
Author(s):  
Pere Barriobero-Vila ◽  
Guillermo Requena ◽  
Fernando Warchomicka ◽  
Andreas Stark ◽  
Norbert Schell ◽  
...  
Keyword(s):  
Phase Transformation ◽  
Continuous Heating ◽  
Transformation Kinetics ◽  
Phase Transformation Kinetics

Modeling Phase Transformation Kinetics and Their Effect on Hardness and Hardness Depth in Laser Hardening of Hypoeutectoid Steel

2015 ◽  
Author(s):  
Suhash Ghosh ◽  
Chittaranjan Sahay
Keyword(s):  
Thermal Analysis ◽  
Phase Transformation ◽  
Phase Transformations ◽  
Laser Hardening ◽  
Temperature History ◽  
Transformation Kinetics ◽  
Continuous Cooling ◽  
Phase Transformation Kinetics ◽  
Hardness Depth ◽  
Hypoeutectoid Steel

Much research has been done to model laser hardening phase transformation kinetics. In that research, assumptions are made about the austenization of the steel that does not translate into accurate hardness depth calculations. The purpose of this paper is to develop an analytical method to accurately model laser hardening phase transformation kinetics of hypoeutectoid steel, accounting for non-homogeneous austenization. The modeling is split into two sections. The first models the transient thermal analysis to obtain temperature time-histories for each point in the workpiece. The second models non-homogeneous austenization and utilizes continuous cooling curves to predict microstructure and hardness. Non-homogeneous austenization plays a significant role in the hardness and hardness depth in the steel. A finite element based three-dimensional thermal analysis in ANSYS is performed to obtain the temperature history on three steel workpieces for laser hardening process with no melting; AISI 1030, 1040 and 1045 steels. This is followed by the determination of microstructural changes due to ferrite and pearlite transformation to austenite during heating and the subsequent austenite to martensite and other diffusional transformations during cooling. Johnson-Mehl-Avrami-Kolmogorov (JMAK) equation is used to track the phase transformations during heating, including the effects of non-homogenous austenitization. The solid state nodal phase transformations during cooling are monitored on the material’s digitized Continuous Cooling Transformation (CCT) curve through a user defined input file in ANSYS for all cooling rates within the Heat Affected Zone (HAZ). Material non-linearity is included in the model by including temperature dependent thermal properties for the material. The model predictions for hardness underneath the laser and the HAZ match well with the experimental results published in literature.

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