## Phase Transformation

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### Allan S. Myerson - One of the best experts on this subject based on the ideXlab platform.

• ##### Phase Transformation of Sulfamerazine Using a Taylor Vortex
2016
Co-Authors: Sun Lee, Areum Choi, Woo-sik Kim, Allan S. Myerson
Abstract:

A Couette–Taylor (CT) crystallizer was used to demonstrate the unique fluid dynamic properties of a Taylor vortex for the Phase Transformation of sulfamerazine (SMZ). With a conventional Rushton mixing tank (MT) crystallizer, the Phase Transformation from a metastable crystalline Phase to the stable crystalline Phase took more than 60 h with acetonitrile (ACN) as the solvent and an agitation rate of 3000 rpm. Using a CT crystallizer, this Phase Transformation occurred within 3–7 h with rotation speeds in the CT crystallizer of 300–1000 rpm. Increasing the rotation speed of the CT crystallizer also significantly enhanced the Phase Transformation, whereas adding water to the solvent increased the solubility difference between the two polymorphs and accelerated the Phase Transformation in both crystallizers. The Phase Transformation in the CT crystallizer was always many times faster than that in the MT crystallizer. Nucleation and mass-transfer models were used to describe the nucleation induction time of the stable crystal form and the Transformation of metastable crystals into stable crystals. The influence of the fluid motions of the periodic Taylor vortex and random eddy in the CT and MT crystallizer, respectively, on the induction time was correlated by the nucleation enhancement factor, which was expressed as function of energy dissipation. The resulting induction and Transformation times correlated well with the experimental data in terms of the energy dissipation and solubility difference across the whole range of Phase Transformation conditions, including rotation speeds, water fractions, and temperatures

• ##### Phase Transformation of Sulfamerazine Using a Taylor Vortex
Crystal Growth & Design, 2011
Co-Authors: Sun Lee, Areum Choi, Allan S. Myerson
Abstract:

A Couette–Taylor (CT) crystallizer was used to demonstrate the unique fluid dynamic properties of a Taylor vortex for the Phase Transformation of sulfamerazine (SMZ). With a conventional Rushton mixing tank (MT) crystallizer, the Phase Transformation from a metastable crystalline Phase to the stable crystalline Phase took more than 60 h with acetonitrile (ACN) as the solvent and an agitation rate of 3000 rpm. Using a CT crystallizer, this Phase Transformation occurred within 3–7 h with rotation speeds in the CT crystallizer of 300–1000 rpm. Increasing the rotation speed of the CT crystallizer also significantly enhanced the Phase Transformation, whereas adding water to the solvent increased the solubility difference between the two polymorphs and accelerated the Phase Transformation in both crystallizers. The Phase Transformation in the CT crystallizer was always many times faster than that in the MT crystallizer. Nucleation and mass-transfer models were used to describe the nucleation induction time of t...

### D Xia - One of the best experts on this subject based on the ideXlab platform.

• ##### the effects of solid state Phase Transformation upon stress evolution in laser metal powder deposition
Materials & Design, 2015
Co-Authors: Jinxiang Fang, Shiyun Dong, Yujiang Wang, Z H Zhang, D Xia
Abstract:

Abstract To investigate the influences of solid-state Phase Transformation on stress evolution during multi-pass laser metal powder deposition (LMPD) process, a 3D finite-element (FE) thermo-mechanical model considering Phase Transformation has been established. The influences of Phase Transformation such as mechanical properties changes, volume change and Transformation induced plasticity (TRIP) are taken into account. Furthermore, the influences of high magnitude stress upon martensitic Transformation characteristic temperature and TRIP are considered. The temperature and history (microstructure) dependent material properties used in the present research are obtained by experiments. The stress field during LMPD process is analyzed with and without solid-state Phase Transformation, respectively. Stress measurement of X-ray diffraction (XRD) method is applied to deposited samples, and the measuring data are compared with the computational predictions. The results show that Phase Transformation has a dominant effect on the stress evolution, longitudinal residual stresses significantly reduced as a result of solid-state Phase Transformation. In addition, the effect of stresses on martensitic Transformation temperature is important for accurate prediction of residual stresses (stress state after cooling of the clad to ambient temperature). Residual stresses are lower when the Phase Transformation temperature is reduced.

### Lars O. Jernkvist - One of the best experts on this subject based on the ideXlab platform.

• ##### Solid state Phase Transformation kinetics in Zr-base alloys
Scientific Reports, 2021
Co-Authors: A. R. Massih, Lars O. Jernkvist
Abstract:

We 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.

### Sun Lee - One of the best experts on this subject based on the ideXlab platform.

• ##### Phase Transformation of Sulfamerazine Using a Taylor Vortex
2016
Co-Authors: Sun Lee, Areum Choi, Woo-sik Kim, Allan S. Myerson
Abstract:

A Couette–Taylor (CT) crystallizer was used to demonstrate the unique fluid dynamic properties of a Taylor vortex for the Phase Transformation of sulfamerazine (SMZ). With a conventional Rushton mixing tank (MT) crystallizer, the Phase Transformation from a metastable crystalline Phase to the stable crystalline Phase took more than 60 h with acetonitrile (ACN) as the solvent and an agitation rate of 3000 rpm. Using a CT crystallizer, this Phase Transformation occurred within 3–7 h with rotation speeds in the CT crystallizer of 300–1000 rpm. Increasing the rotation speed of the CT crystallizer also significantly enhanced the Phase Transformation, whereas adding water to the solvent increased the solubility difference between the two polymorphs and accelerated the Phase Transformation in both crystallizers. The Phase Transformation in the CT crystallizer was always many times faster than that in the MT crystallizer. Nucleation and mass-transfer models were used to describe the nucleation induction time of the stable crystal form and the Transformation of metastable crystals into stable crystals. The influence of the fluid motions of the periodic Taylor vortex and random eddy in the CT and MT crystallizer, respectively, on the induction time was correlated by the nucleation enhancement factor, which was expressed as function of energy dissipation. The resulting induction and Transformation times correlated well with the experimental data in terms of the energy dissipation and solubility difference across the whole range of Phase Transformation conditions, including rotation speeds, water fractions, and temperatures

• ##### Phase Transformation of Sulfamerazine Using a Taylor Vortex
Crystal Growth & Design, 2011
Co-Authors: Sun Lee, Areum Choi, Allan S. Myerson
Abstract:

A Couette–Taylor (CT) crystallizer was used to demonstrate the unique fluid dynamic properties of a Taylor vortex for the Phase Transformation of sulfamerazine (SMZ). With a conventional Rushton mixing tank (MT) crystallizer, the Phase Transformation from a metastable crystalline Phase to the stable crystalline Phase took more than 60 h with acetonitrile (ACN) as the solvent and an agitation rate of 3000 rpm. Using a CT crystallizer, this Phase Transformation occurred within 3–7 h with rotation speeds in the CT crystallizer of 300–1000 rpm. Increasing the rotation speed of the CT crystallizer also significantly enhanced the Phase Transformation, whereas adding water to the solvent increased the solubility difference between the two polymorphs and accelerated the Phase Transformation in both crystallizers. The Phase Transformation in the CT crystallizer was always many times faster than that in the MT crystallizer. Nucleation and mass-transfer models were used to describe the nucleation induction time of t...

### Jinxiang Fang - One of the best experts on this subject based on the ideXlab platform.

• ##### the effects of solid state Phase Transformation upon stress evolution in laser metal powder deposition
Materials & Design, 2015
Co-Authors: Jinxiang Fang, Shiyun Dong, Yujiang Wang, Z H Zhang, D Xia
Abstract:

Abstract To investigate the influences of solid-state Phase Transformation on stress evolution during multi-pass laser metal powder deposition (LMPD) process, a 3D finite-element (FE) thermo-mechanical model considering Phase Transformation has been established. The influences of Phase Transformation such as mechanical properties changes, volume change and Transformation induced plasticity (TRIP) are taken into account. Furthermore, the influences of high magnitude stress upon martensitic Transformation characteristic temperature and TRIP are considered. The temperature and history (microstructure) dependent material properties used in the present research are obtained by experiments. The stress field during LMPD process is analyzed with and without solid-state Phase Transformation, respectively. Stress measurement of X-ray diffraction (XRD) method is applied to deposited samples, and the measuring data are compared with the computational predictions. The results show that Phase Transformation has a dominant effect on the stress evolution, longitudinal residual stresses significantly reduced as a result of solid-state Phase Transformation. In addition, the effect of stresses on martensitic Transformation temperature is important for accurate prediction of residual stresses (stress state after cooling of the clad to ambient temperature). Residual stresses are lower when the Phase Transformation temperature is reduced.