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T Buslaps - One of the best experts on this subject based on the ideXlab platform.
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influence of Phase Transformation Kinetics on the formation of α in a β quenched ti 5al 5mo 5v 3cr 1zr alloy
Acta Materialia, 2015Co-Authors: Pere Barrioberovila, Guillermo Requena, Fernando Warchomicka, Sabine Schwarz, T BuslapsAbstract:Abstract The effect of Phase Transformation Kinetics on the formation of α in the β-quenched Ti–5Al–5Mo–5V–3Cr–1Zr metastable β titanium alloy is investigated as a function of heating rate by means of in situ high energy synchrotron X-ray diffraction complemented by metallographic analysis. Quantitative Phase analysis based on the Rietveld method provides the continuous evolution of Phase volume fractions and lattice parameters, revealing variations in the Phase Transformation sequence with increasing heating rate. The initial microstructure consists in a matrix of equiaxed metastable β grains with ωath particles located along dislocation lines as well as within domains associated with spinodal decomposition of β. During the first stage of slow heating diffusion-driven formation of the metastable Phases ω and α iso ″ takes place with further decomposition of β. This effect contributes to the formation of ω and is observed as a symmetric pattern of parallel domains that reflect compositional modulations in the matrix. Evidences of the role of dislocations during Phase Transformation are presented. Furthermore, the results show that the stable α Phase forms via two different paths: (a) slow heating rates provide homogeneous distribution of fine α plates formed through the evolution of ω, while (b) fast heating rates suppress this mechanism and promote the formation of α only from β grain boundaries.
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role of element partitioning on the α β Phase Transformation Kinetics of a bi modal ti 6al 6v 2sn alloy during continuous heating
Journal of Alloys and Compounds, 2015Co-Authors: Pere Barrioberovila, Guillermo Requena, T Buslaps, Matthias Alfeld, Ulrike BoesenbergAbstract:Abstract The role of element partitioning on the Phase Transformation Kinetics of a bi-modal α + β Ti–6Al–6V–2Sn alloy is studied experimentally as a function of heating rate combining quantitative Phase analysis with elemental analysis. The evolution of Phase volume fractions and lattice parameters is investigated by in situ high energy synchrotron X-ray diffraction and conventional metallographic analysis. Synchrotron micro X-ray fluorescence and energy dispersive X-ray spectroscopy are applied to trace microstructural distribution of alloying elements during heating. The linear increase of the lattice parameters observed for all conditions at the beginning of the heating is associated to lattice thermal expansion. Thereafter, at intermediate temperatures, the alloy undergoes a β to α Transformation for low heating rates. Element partitioning results in an enrichment of α and β by their respective stabilizing elements and a consequent nonlinear variation of the lattice parameters. As the temperature increases, α transforms into β up to the β-transus temperature. Microstructural evidences of the role of V during Phase Transformation are presented. Moreover, nonlinear variations of the β lattice parameter are related to the role of alloying elements on the different stages of element partitioning. The analysis of Phase Transformation Kinetics combining laboratory and synchrotron-based techniques provides an advance in the current knowledge of the Phase Transformation Kinetics of the Ti–6Al–6V–2Sn alloy that can help to develop new theoretical models and, consequently, knowledge-based thermal treatment optimization.
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Phase Transformation Kinetics during continuous heating of a β quenched ti 10v 2fe 3al alloy
Journal of Materials Science, 2015Co-Authors: Pere Barrioberovila, Guillermo Requena, Fernando Warchomicka, Andreas Stark, Norbert Schell, T BuslapsAbstract:The effect of heating rate on the Phase Transformation Kinetics of a Ti–10V–2Fe–3Al metastable β titanium alloy quenched from the β field is investigated by fast in situ high energy synchrotron X-ray diffraction and differential scanning calorimetry. The initial microstructure is formed by α″ martensite and fine ωath particles distributed in the retained β-Phase matrix. The Phase Transformation sequence varies with the heating rate as revealed by analysis of the continuous evolution of crystallographic relationships between Phases. At low temperatures an athermal reversion of α″ martensite into β takes place. This reversion occurs to a larger extent with increasing heating rate. On the other hand, diffusion–driven precipitation and growth of the ω Phase is observed for lower heating rates accompanying the reverse martensitic Transformation. Furthermore, the results show that the stable α Phase can form through three different paths: (a) from the ω Phase, (b) from α″ martensite, and (c) from the β Phase.
Guillermo Requena - One of the best experts on this subject based on the ideXlab platform.
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influence of Phase Transformation Kinetics on the formation of α in a β quenched ti 5al 5mo 5v 3cr 1zr alloy
Acta Materialia, 2015Co-Authors: Pere Barrioberovila, Guillermo Requena, Fernando Warchomicka, Sabine Schwarz, T BuslapsAbstract:Abstract The effect of Phase Transformation Kinetics on the formation of α in the β-quenched Ti–5Al–5Mo–5V–3Cr–1Zr metastable β titanium alloy is investigated as a function of heating rate by means of in situ high energy synchrotron X-ray diffraction complemented by metallographic analysis. Quantitative Phase analysis based on the Rietveld method provides the continuous evolution of Phase volume fractions and lattice parameters, revealing variations in the Phase Transformation sequence with increasing heating rate. The initial microstructure consists in a matrix of equiaxed metastable β grains with ωath particles located along dislocation lines as well as within domains associated with spinodal decomposition of β. During the first stage of slow heating diffusion-driven formation of the metastable Phases ω and α iso ″ takes place with further decomposition of β. This effect contributes to the formation of ω and is observed as a symmetric pattern of parallel domains that reflect compositional modulations in the matrix. Evidences of the role of dislocations during Phase Transformation are presented. Furthermore, the results show that the stable α Phase forms via two different paths: (a) slow heating rates provide homogeneous distribution of fine α plates formed through the evolution of ω, while (b) fast heating rates suppress this mechanism and promote the formation of α only from β grain boundaries.
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role of element partitioning on the α β Phase Transformation Kinetics of a bi modal ti 6al 6v 2sn alloy during continuous heating
Journal of Alloys and Compounds, 2015Co-Authors: Pere Barrioberovila, Guillermo Requena, T Buslaps, Matthias Alfeld, Ulrike BoesenbergAbstract:Abstract The role of element partitioning on the Phase Transformation Kinetics of a bi-modal α + β Ti–6Al–6V–2Sn alloy is studied experimentally as a function of heating rate combining quantitative Phase analysis with elemental analysis. The evolution of Phase volume fractions and lattice parameters is investigated by in situ high energy synchrotron X-ray diffraction and conventional metallographic analysis. Synchrotron micro X-ray fluorescence and energy dispersive X-ray spectroscopy are applied to trace microstructural distribution of alloying elements during heating. The linear increase of the lattice parameters observed for all conditions at the beginning of the heating is associated to lattice thermal expansion. Thereafter, at intermediate temperatures, the alloy undergoes a β to α Transformation for low heating rates. Element partitioning results in an enrichment of α and β by their respective stabilizing elements and a consequent nonlinear variation of the lattice parameters. As the temperature increases, α transforms into β up to the β-transus temperature. Microstructural evidences of the role of V during Phase Transformation are presented. Moreover, nonlinear variations of the β lattice parameter are related to the role of alloying elements on the different stages of element partitioning. The analysis of Phase Transformation Kinetics combining laboratory and synchrotron-based techniques provides an advance in the current knowledge of the Phase Transformation Kinetics of the Ti–6Al–6V–2Sn alloy that can help to develop new theoretical models and, consequently, knowledge-based thermal treatment optimization.
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Phase Transformation Kinetics during continuous heating of a β quenched ti 10v 2fe 3al alloy
Journal of Materials Science, 2015Co-Authors: Pere Barrioberovila, Guillermo Requena, Fernando Warchomicka, Andreas Stark, Norbert Schell, T BuslapsAbstract:The effect of heating rate on the Phase Transformation Kinetics of a Ti–10V–2Fe–3Al metastable β titanium alloy quenched from the β field is investigated by fast in situ high energy synchrotron X-ray diffraction and differential scanning calorimetry. The initial microstructure is formed by α″ martensite and fine ωath particles distributed in the retained β-Phase matrix. The Phase Transformation sequence varies with the heating rate as revealed by analysis of the continuous evolution of crystallographic relationships between Phases. At low temperatures an athermal reversion of α″ martensite into β takes place. This reversion occurs to a larger extent with increasing heating rate. On the other hand, diffusion–driven precipitation and growth of the ω Phase is observed for lower heating rates accompanying the reverse martensitic Transformation. Furthermore, the results show that the stable α Phase can form through three different paths: (a) from the ω Phase, (b) from α″ martensite, and (c) from the β Phase.
Eric J Mittemeijer - One of the best experts on this subject based on the ideXlab platform.
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Phase Transformation Kinetics advanced modeling strategies
JOM, 2013Co-Authors: B Rheingans, Eric J MittemeijerAbstract:Phase Transformations in the solid state are often heterogeneous and can be described by concurring modes of nucleation, growth, and impingement. The classical Johnson–Mehl–Avrami–Kolmogorov-(JMAK-) model, although offering an easy-to-use description of the Transformation Kinetics, is limited to very specific cases of the Transformation modes. Instead, a generalized modular model of Phase Transformation Kinetics can be proposed that provides a flexible formalism adaptable to various modes of nucleation, growth, and impingement. Due to its large versatility, the modular model approach can be easily applied for characterization of Phase Transformation Kinetics beyond the scope of classical JMAK(-type) modeling. Three different strategies recently employed for such advanced modeling are presented: (I) deliberate variation of the nucleation mode upon crystallization of an Fe-Ni-B metallic glass in order to determine separate activation energies for nucleation and growth, (II) incorporation of specific, dedicated modes for nucleation and growth Kinetics for the allotropic hcp–fcc Transformation in cobalt introducing driving-force-dependent rates of Transformation, and (III) implementation of quantitative microstructural data for the description of the precipitation Kinetics in a supersaturated CuCo alloy.
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solid state Phase Transformation Kinetics evaluation of the modular Transformation model
International Journal of Materials Research, 2011Co-Authors: Eric J Mittemeijer, F SommerAbstract:Abstract An evaluation of the (most) recent developments of the modular Transformation model, for describing the Kinetics of solid–solid Phase Transformations, has been made. As a result a two-step procedure for its practical application has been proposed. On this basis the operating nucleation, growth and impingement modes can be identified and quantified. The model has been shown to be applicable to very diverse Transformations, as demonstrated by examples taken up in this paper.
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Kinetics of the allotropic hcp fcc Phase Transformation in cobalt
Philosophical Magazine, 2011Co-Authors: Rico Bauer, Eric Aime Jagle, Wolfgang Baumann, Eric J MittemeijerAbstract:The allotropic, martensitic Phase Transformation (hcp → fcc) in cobalt was investigated by differential scanning calorimetry (DSC) upon isochronal annealing at heating rates in the range from 10 K min−1 to 40 K min−1. The microstructural evolution was traced by optical microscopy and X-ray diffractometry. The Kinetics of the Phase Transformation from hcp to fcc Co upon isochronal annealing was described on the basis of a modular Phase Transformation model. Appropriate model descriptions for athermal nucleation and thermally activated, anisotropic interface controlled growth tailored to the martensitic Phase Transformation of Co were implemented into the modular model. Fitting of this model of Phase Transformation Kinetics to simultaneously all isochronal DSC runs yielded values for the energy of the interface separating the hcp and fcc Co Phase and the activation energy for growth.
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predicting microstructures from Phase Transformation Kinetics the case of isochronal heating and cooling from a supersaturated matrix
Modelling and Simulation in Materials Science and Engineering, 2010Co-Authors: Eric Aime Jagle, Eric J MittemeijerAbstract:Microstructures resulting from nucleation and growth Phase Transformations occurring under various time–temperature programs were simulated and analysed. The Transformation Kinetics was described by a modular kinetic model and information from this model was used to provide 'global' rules for application in a geometric algorithm to simulate the microstructure. The microstructures for heating and cooling Transformations, in particular as revealed by the grain-size distributions (GSDs), differ distinctly as a consequence of the different temperature dependences of the nucleation and growth rates. The differences in grain-size distributions on the basis of volume-weighted, area-weighted and line-intercept grain sizes were discussed in the light of their sensitivity for revealing the Kinetics of the underlying Phase Transformation.
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analysis of solid state Phase Transformation Kinetics models and recipes
International Materials Reviews, 2007Co-Authors: F Sommer, Eric J MittemeijerAbstract:The progress of solid-state Phase Transformations can generally be subdivided into three overlapping mechanisms: nucleation, growth and impingement. These can be modelled separately if hard impingement prevails. On that basis, an overview has been given of recent numerical and analytical methods for determination of the kinetic parameters of a Transformation. The treatment focuses on both isothermally and isochronally conducted Transformations. To extend the range of Transformations that can be described analytically, a number of more or less empirical submodels, which are compatible with experimental results, has been included in the discussion. It has been shown that powerful, flexible, analytical models are possible, once the concept of time or temperature dependent growth exponent and effective activation energy, in agreement with the existing experimental observations, has been adopted. An explicit (numerical) procedure to deduce the operating kinetic processes from experimental Transformation-rate data, on the basis of different nucleation, growth and hard impingement mechanisms, has been demonstrated. Without recourse to any specific kinetic model, simple recipes have been given for the determination of the growth exponent and the effective activation energy from the experimental Transformation-rate data.
Pere Barrioberovila - One of the best experts on this subject based on the ideXlab platform.
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influence of Phase Transformation Kinetics on the formation of α in a β quenched ti 5al 5mo 5v 3cr 1zr alloy
Acta Materialia, 2015Co-Authors: Pere Barrioberovila, Guillermo Requena, Fernando Warchomicka, Sabine Schwarz, T BuslapsAbstract:Abstract The effect of Phase Transformation Kinetics on the formation of α in the β-quenched Ti–5Al–5Mo–5V–3Cr–1Zr metastable β titanium alloy is investigated as a function of heating rate by means of in situ high energy synchrotron X-ray diffraction complemented by metallographic analysis. Quantitative Phase analysis based on the Rietveld method provides the continuous evolution of Phase volume fractions and lattice parameters, revealing variations in the Phase Transformation sequence with increasing heating rate. The initial microstructure consists in a matrix of equiaxed metastable β grains with ωath particles located along dislocation lines as well as within domains associated with spinodal decomposition of β. During the first stage of slow heating diffusion-driven formation of the metastable Phases ω and α iso ″ takes place with further decomposition of β. This effect contributes to the formation of ω and is observed as a symmetric pattern of parallel domains that reflect compositional modulations in the matrix. Evidences of the role of dislocations during Phase Transformation are presented. Furthermore, the results show that the stable α Phase forms via two different paths: (a) slow heating rates provide homogeneous distribution of fine α plates formed through the evolution of ω, while (b) fast heating rates suppress this mechanism and promote the formation of α only from β grain boundaries.
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role of element partitioning on the α β Phase Transformation Kinetics of a bi modal ti 6al 6v 2sn alloy during continuous heating
Journal of Alloys and Compounds, 2015Co-Authors: Pere Barrioberovila, Guillermo Requena, T Buslaps, Matthias Alfeld, Ulrike BoesenbergAbstract:Abstract The role of element partitioning on the Phase Transformation Kinetics of a bi-modal α + β Ti–6Al–6V–2Sn alloy is studied experimentally as a function of heating rate combining quantitative Phase analysis with elemental analysis. The evolution of Phase volume fractions and lattice parameters is investigated by in situ high energy synchrotron X-ray diffraction and conventional metallographic analysis. Synchrotron micro X-ray fluorescence and energy dispersive X-ray spectroscopy are applied to trace microstructural distribution of alloying elements during heating. The linear increase of the lattice parameters observed for all conditions at the beginning of the heating is associated to lattice thermal expansion. Thereafter, at intermediate temperatures, the alloy undergoes a β to α Transformation for low heating rates. Element partitioning results in an enrichment of α and β by their respective stabilizing elements and a consequent nonlinear variation of the lattice parameters. As the temperature increases, α transforms into β up to the β-transus temperature. Microstructural evidences of the role of V during Phase Transformation are presented. Moreover, nonlinear variations of the β lattice parameter are related to the role of alloying elements on the different stages of element partitioning. The analysis of Phase Transformation Kinetics combining laboratory and synchrotron-based techniques provides an advance in the current knowledge of the Phase Transformation Kinetics of the Ti–6Al–6V–2Sn alloy that can help to develop new theoretical models and, consequently, knowledge-based thermal treatment optimization.
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Phase Transformation Kinetics during continuous heating of a β quenched ti 10v 2fe 3al alloy
Journal of Materials Science, 2015Co-Authors: Pere Barrioberovila, Guillermo Requena, Fernando Warchomicka, Andreas Stark, Norbert Schell, T BuslapsAbstract:The effect of heating rate on the Phase Transformation Kinetics of a Ti–10V–2Fe–3Al metastable β titanium alloy quenched from the β field is investigated by fast in situ high energy synchrotron X-ray diffraction and differential scanning calorimetry. The initial microstructure is formed by α″ martensite and fine ωath particles distributed in the retained β-Phase matrix. The Phase Transformation sequence varies with the heating rate as revealed by analysis of the continuous evolution of crystallographic relationships between Phases. At low temperatures an athermal reversion of α″ martensite into β takes place. This reversion occurs to a larger extent with increasing heating rate. On the other hand, diffusion–driven precipitation and growth of the ω Phase is observed for lower heating rates accompanying the reverse martensitic Transformation. Furthermore, the results show that the stable α Phase can form through three different paths: (a) from the ω Phase, (b) from α″ martensite, and (c) from the β Phase.
E J Mittemeijer - One of the best experts on this subject based on the ideXlab platform.
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evaluation of the maximum Transformation rate for analyzing solid state Phase Transformation Kinetics
Acta Materialia, 2009Co-Authors: F Liu, Shaojie Song, F Sommer, E J MittemeijerAbstract:Abstract An evaluation of the maximum in the Transformation rate of a solid-state Transformation is given for isothermal and isochronal Transformations, on the basis of a general, flexible, analytical Transformation model incorporating different combinations of nucleation, growth and impingement modes. For isothermal Phase Transformations, the position of the peak maximum is determined by the growth exponent and the impingement mode whereas, for isochronal Phase Transformations, only the impingement mode influences the position of the peak maximum. A straightforward method has been developed for determining the mode of impingement and the separate activation energies for nucleation and growth. The results obtained by application of the proposed Transformation-rate maximum analysis to model systems are in good agreement with the values assigned to the kinetic parameters of the model systems. The proposed recipes have also been applied successfully to experimental data on the crystallization of an initially amorphous Mg–Cu–Y alloy.
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parameter determination of an analytical model for Phase Transformation Kinetics application to crystallization of amorphous mg ni alloys
Journal of Materials Research, 2004Co-Authors: F Liu, F Sommer, E J MittemeijerAbstract:This study used an analytical model for Phase-Transformation Kinetics. We used different combinations of various nucleation mechanisms [mixed nucleation (site saturation plus continuous nucleation), Avrami nucleation, and site saturation plus Avrami nucleation] and growth mechanisms (volume diffusion-controlled growth and interface-controlled growth) for a single Transformation. Our work incorporated the effect of impingement of the growing particles. These factors have been applied to the same experimental results to find out the prevauling mechanisms. We made a detauled analysis for the determination of the parameters of the analytical Phase-Transformation model, in order to determine the most reasonable nucleation and growth modes, and the values for the activation energies of nucleation and growth. We used the model to study the crystallization Kinetics of Mg82Ni18 and Mg88.7NiP11.3, as measured by means of both isothermal and isochronal differential scanning calorimetry.
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solid state Phase Transformation Kinetics a modular Transformation model
Zeitschrift Fur Metallkunde, 2002Co-Authors: E J Mittemeijer, F SommerAbstract:Abstract A modular model for the Kinetics of solid state Phase Transformations has been discussed, recognising three mechanisms: nucleation, growth, and impingement of growing new Phase particles. For each of the three constituting mechanisms, several model descriptions can be incorporated. The choice for one specific (mathematical) description is based on microstructural information, thermodynamic data and available knowledge of the Kinetics about the Phase Transformation concerned. The model is valid for both isothermally as well as non-isothermally conducted Transformations. The model kinetic parameters are independent of the time–temperature program. In certain specific cases, the model can be simplified such that it reduces to so-called Johnson-Mehl-Avrami Kinetics. From the kinetic model a method resulted to obtain the activation energies for nucleation and growth separately. The model has been applied successfully to a number of diverse Transformations, involving the crystallisation of Pd40Cu30P20N...