Multiphase precipitation of carbides in Fe-C systems: Part I. Model based upon simple kinetic reactions

Luiggi, Ney; Betancourt, Angel E.

doi:10.1007/bf02662774

Cited by 21 publications

(16 citation statements)

References 10 publications

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“…In this case, where the transformation is performed by means of the simultaneous or nonsimultaneous precipitation of two phases-one metastable phase which evolves to give way to a stable one-it is necessary to consider, at least, as many differential equations as different phases there are present in the process. [10,11] In this sense, we have mathematically shown that for the most simple cases of atom transference, [10] the fraction Y is written as the sum of the heightened precipitation kernels. For more complex cases, we assume that this relation is still valid, which allows us to write…”

Section: Theoretical Aspectsmentioning

confidence: 98%

“…In order to evaluate the basic characteristics of the precipitated phases for the 3003 Al alloy after it has been heat treated, this work combines the results of our previous one, [1,10,11] taking into account our models of kernel precipitation for both the JMA and Fujita-Damask (FD) types. The organization of this article is as follows: Section II presents a view of the experimental aspects.…”

Section: Introductionmentioning

confidence: 99%

“…Luiggi and Betancourt, [10,11] in their works on reactions rate kinetics, developed equations to follow the decomposition of a solid solution to reach the equilibrium state, by following different paths of atomic exchange between the possible existing phases. This allows them to propose a general equation where a kernel of precipitation is assigned to each existing phase.…”

Section: Introductionmentioning

confidence: 99%

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Analysis of thermoelectric power measurements in the study of precipitation kinetics in 3003 Al alloy

Luiggi

1997

Metall Mater Trans B

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Analysis of Thermoelectric Power Measurements in the Study of Precipitation Kinetics in 3003 Al AlloyNEY JOSÉ LUIGGI Multiphase precipitation kinetics for a 3003 aluminum alloy, pointed out in our previous work [1] and obtained under different microstructural conditions by thermoelectric power measurements, is now modeled under the light of the theory of reaction rates. Our multiphase model encompasses the precipitation kernels of Johnson-Mehl-Avrami (JMA) and of Fujita-Damask (FD), which adequately reproduce the experimental kinetics. The JMA kernel generates almost constant values for the exponent n. These values are less than one in temperature ranges where the log of the rate constant k grows linearly with the inverse of the temperature. The FD kernel provides an idea of the average critical size of the phase which is formed. Our multiphase results are compared with those obtained from the traditional monophase considerations rendering evident important differences between both models. The total kinetics is deconvoluted, allowing us to characterize the different metastable and stable phases formed according to the different microstructural conditions. The activation energy for kinetics in ''as-cast'' samples behaves differently from that obtained from the microstructures in homogenized and homogenized-strained samples. The activation energy for each of these cases is reported.

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Section: Theoretical Aspectsmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Analysis of thermoelectric power measurements in the study of precipitation kinetics in 3003 Al alloy

Luiggi

1997

Metall Mater Trans B

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“…In a future work, we will give details of the evaluation of those parameters using the multiphase theoretical model for the precipitation process of Luiggi and Betancourt. [13,14] …”

Section: Introductionmentioning

confidence: 98%

Isothermal precipitation of commercial 3003 Al alloys studied by thermoelectric power

Luiggi

1997

Metall Mater Trans B

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We have used thermoelectric power (TEP) techniques to study the precipitation process in samples of cold-rolled commercial 3003 Al alloys, in which we guarantee the initial microstructure by diverse thermal treatments. Kinetics are obtained, isothermally, at several aging temperatures, proving that the manganese impurity controls the precipitation process. The Nordheim-Gorter rule is used to determine the effect of impurities on the diffusional TEP, permitting us to know the amount of Mn in solid solution for the diverse work conditions. The time-temperature-transformation (TTT) curves, obtained from the isothermal kinetics plots, indicate the existence of different precipitate phases which depend upon the thermal treatment applied to the sample. For homogenized samples, the observed behavior was associated to an equilibrium phase with a nose toward 540 ЊC and with an activation energy of (41 ‫ע‬ 2) Kcal/mol. For strained samples, we observe a metastable phase with an activation energy of (19 ‫ע‬ 2) Kcal/mol and also a stable phase with an activation energy similar to the one obtained for the homogenized samples. For as-cast and as-cast-heated samples, we predict the existence of two precipitated phases, the activation energy of the precipitated phase at low temperature being (31 ‫ע‬ 2) Kcal/mol. The energy of the second phase seems to be the same for all microstructural conditions. The results obtained for the stable phase agree with the results reported in the literature.

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“…In other works some attempts have been made [34][35][36][37] to deconvolute such experimental master curves into components due to individual processes, but it is difficult to see whether some of these fitting parameters have any physical meaning.…”

Section: Introductionmentioning

confidence: 99%

Comments About the Strengthening Mechanisms in Commercial Microalloyed Steels and Reaction Kinetics on Tempering in Low-Alloy Steels

Morales¹

2011

Alloy Steel - Properties and Use

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Multiphase precipitation of carbides in Fe-C systems: Part I. Model based upon simple kinetic reactions

Cited by 21 publications

References 10 publications

Analysis of thermoelectric power measurements in the study of precipitation kinetics in 3003 Al alloy

Analysis of thermoelectric power measurements in the study of precipitation kinetics in 3003 Al alloy

Isothermal precipitation of commercial 3003 Al alloys studied by thermoelectric power

Comments About the Strengthening Mechanisms in Commercial Microalloyed Steels and Reaction Kinetics on Tempering in Low-Alloy Steels

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