Evaluation of the maximum transformation rate for analyzing solid-state phase transformation kinetics

Liu, F.; Song, Shaojie; Sommer, F.; Mittemeijer, E. J.

doi:10.1016/j.actamat.2009.08.046

Cited by 61 publications

(38 citation statements)

References 26 publications

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“…Several authors have described the influence of the activation energies of nucleation and growth on the effective activation energy and described numerical solutions for obtaining the individual activation energies from the overall activation energy. [36,[46][47][48] The higher values for the activation energy found in this work are thus believed to be an effective activation energy comprising the energies of both the mechanisms involved, i.e., nucleation and growth. Furthermore, the activation energies obtained for the two stages are similar to those found by Kapoor et al [40] for the precipitation hardening steel PH 13-8Mo, where the martensite-to-austenite transformation occurs through a diffusional mechanism in two stages.…”

Section: A Austenite Formation In Two Stagesmentioning

confidence: 96%

Austenite Formation from Martensite in a 13Cr6Ni2Mo Supermartensitic Stainless Steel

Bojack

Zhao

Morris

et al. 2016

Metall Mater Trans A

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The influence of austenitization treatment of a 13Cr6Ni2Mo supermartensitic stainless steel (X2CrNiMoV13-5-2) on austenite formation during reheating and on the fraction of austenite retained after tempering treatment is measured and analyzed. The results show the formation of austenite in two stages. This is probably due to inhomogeneous distribution of the austenite-stabilizing elements Ni and Mn, resulting from their slow diffusion from martensite into austenite and carbide and nitride dissolution during the second, higher temperature, stage. A better homogenization of the material causes an increase in the transformation temperatures for the martensite-to-austenite transformation and a lower retained austenite fraction with less variability after tempering. Furthermore, the martensite-to-austenite transformation was found to be incomplete at the target temperature of 1223 K (950°C), which is influenced by the previous austenitization treatment and the heating rate. The activation energy for martensite-to-austenite transformation was determined by a modified Kissinger equation to be approximately 400 and 500 kJ/mol for the first and the second stages of transformation, respectively. Both values are much higher than the activation energy found during isothermal treatment in a previous study and are believed to be effective activation energies comprising the activation energies of both mechanisms involved, i.e., nucleation and growth.

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Section: A Austenite Formation In Two Stagesmentioning

confidence: 96%

Austenite Formation from Martensite in a 13Cr6Ni2Mo Supermartensitic Stainless Steel

Bojack

Zhao

Morris

et al. 2016

Metall Mater Trans A

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“…In such a system the energy barrier may be overcome by thermal fluctuations which gives rise to relaxation effects and a dependence of the transition on the rate of the driving force. This thermal activation over an energy barrier is considered for the magnetization process in general [17,18,19] and for phase transformations in the framework of the JMA model [20,21]. Thermally activated processes consist in the possibility that a small correlated region of volume v 0 and mass m 0 makes the transition with the help of the thermal energy k B T. Such approach is justified for all transitions of exponential type (e.g.…”

Section: Introductionmentioning

confidence: 99%

Rate dependence of the magnetocaloric effect in La-Fe-Si compounds

Kuepferling

Sasso

Basso

2013

EPJ Web of Conferences

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Abstract. The dynamic magnetocaloric effect in La(Fe x Co y Si 1-x-y ) 13 with x=0.9 and low Co content of y=0.015 was analysed by calorimetric measurements at constant magnetic field and constant temperature as well as magnetisation relaxation measurements. It is shown that the rate dependence of the measurement, which leads to an increased entropy hysteresis with increasing rate of the driving force (temperature or magnetic field), can be mainly attributed to a thermal contact resistance R between sample and thermal bath of the measurement setup.

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“…Collisions of growing grains, observed in TEM, of individual phases provoke impingement eect which was investigated using the dependence dα/dt = f (α), based on the value of transformation-rate maxima (α p ) [18]. For all crystallization steps, α p = 0.5 was observed suggesting anisotropic growth being the prevailing type of impingement.…”

Section: Introductionmentioning

confidence: 99%

Thermal Stability and Mechanism of Thermally Induced Crystallization of Fe_73.5Cu₁Nb₃Si_15.5B₇Amorphous Alloy

et al. 2015

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Investigation of thermal stability of the alloy revealed stepwise crystallization process, manifested by two distinct complex exothermic peaks in dierential scanning calorimetry curves. Kinetic parameters of individual crystallization steps were found using the Kissinger and Vyazovkin methods. Structural characterization of thermally treated samples showed formation of dierent iron-based phases including α-Fe(Si), Fe2B, Fe16Nb6Si7 and Fe2Si and some metastable intermediary species. Morphology characterization of the surface and cross-section of the thermally treated samples showed granulated structure composed of several dierent phases and indicated occurrence of impingement eects during crystal growth. Value of estimated lifetime suggested very high stability against crystallization at room temperature and abrupt decrease of lifetime with temperature increase.

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Evaluation of the maximum transformation rate for analyzing solid-state phase transformation kinetics

Cited by 61 publications

References 26 publications

Austenite Formation from Martensite in a 13Cr6Ni2Mo Supermartensitic Stainless Steel

Austenite Formation from Martensite in a 13Cr6Ni2Mo Supermartensitic Stainless Steel

Rate dependence of the magnetocaloric effect in La-Fe-Si compounds

Thermal Stability and Mechanism of Thermally Induced Crystallization of Fe_73.5Cu₁Nb₃Si_15.5B₇Amorphous Alloy

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Evaluation of the maximum transformation rate for analyzing solid-state phase transformation kinetics

Cited by 61 publications

References 26 publications

Austenite Formation from Martensite in a 13Cr6Ni2Mo Supermartensitic Stainless Steel

Austenite Formation from Martensite in a 13Cr6Ni2Mo Supermartensitic Stainless Steel

Rate dependence of the magnetocaloric effect in La-Fe-Si compounds

Thermal Stability and Mechanism of Thermally Induced Crystallization of Fe73.5Cu1Nb3Si15.5B7Amorphous Alloy

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Thermal Stability and Mechanism of Thermally Induced Crystallization of Fe_73.5Cu₁Nb₃Si_15.5B₇Amorphous Alloy