Phase-Field Simulation of Lamellar Structure Formation in MoSi2/NbSi2 Duplex Silicide

2013 ◽  
Vol 1516 ◽  
pp. 309-315 ◽  
Author(s):  
Yuichiro Koizumi ◽  
Toshihiro Yamazaki ◽  
Akihiko Chiba ◽  
Koji Hagihara ◽  
Takayoshi Nakano ◽  
...  
Keyword(s):  
Structure Formation ◽  
Phase Field ◽  
Interfacial Energy ◽  
First Principles ◽  
Lamellar Structure ◽  
Lattice Misfit ◽  
First Principles Calculation ◽  
Cr Addition ◽  
Image Position ◽  
Habit Planes

ABSTRACTWe conducted phase-field simulations of microstructural evolution in C11b-MoSi2 / C40-NbSi2 dual phase alloy with and without Cr-addition to examine the factors responsible for the formation and stability of the lamellar structure on the basis of thermodynamics, micromechanics and first-principles calculations. The first principles calculation was used for evaluating the interfacial energy, segregation energy of solute Cr-atoms and lattice parameters of imaginary disilicides for estimating the effects of solute distribution on the lattice misfit. When both of lattice misfit and the anisotropy of interfacial energy is taken into account, a lamellar structure similar to that observed experimentally is formed. In the absence of Cr-addition, the straightness of lamellar structure decreased slightly. When an isotropic interfacial energy is assumed, lamellar structure is not formed. Instead, a microstructure with habit planes parallel to {1 0 $\bar 1$ 1} plane of C40-phase is formed. Thus, the anisotropy of interfacial energy is crucial for the lamellar structure formation rather than the elastic energy due to lattice misfit.

Phase-Field Study on the Segregation Mechanism of Additive Elements in NbSi2/MoSi2 Duplex Silicide

2013 ◽  
Vol 1516 ◽  
pp. 145-150 ◽  
Author(s):  
Toshihiro Yamazaki ◽  
Yuichiro Koizumi ◽  
Akihiko Chiba ◽  
Koji Hagihara ◽  
Takayoshi Nakano ◽  
...  
Keyword(s):  
Phase Field ◽  
Chemical Interaction ◽  
Equilibrium Phase ◽  
Equilibrium Phase Diagram ◽  
First Principles Calculation ◽  
Diffuse Interface ◽  
Bulk Chemical ◽  
Chemical Free Energy ◽  
Cr Addition ◽  
Lamellar Interfaces

ABSTRACTWe have examined segregation behavior of various alloying elements at lamellar interfaces of C40-NbSi2/C11b-MoSi2 duplex silicide by a phase-field simulation, which takes into account not only bulk chemical free energy but also segregation energy evaluated by the first principles calculation to reflect interaction between solutes and interface. The simulation suggests that segregation behaviors greatly depend on additive elements. In the case of Cr-addition, the C40-phase becomes enriched with Nb and Cr, while the C11b-phase becomes enriched with Mo, which agrees with the equilibrium phase diagram. Slight segregation of Cr atoms is observed at the interface, whereas Nb and Mo concentrations monotonically change across the diffuse interface between C11b and C40 phases. Significant segregations of Zr and Hf are formed at static interfaces, which are attributed to the chemical interaction between solute atoms and the static interface.

Integrating First-Principle Calculation and Phase-Field Simulation for Lithium Dendritic Growth on the Anode of a Lithium-Ion Battery

2016 ◽  
Author(s):  
Lei Chen
Keyword(s):  
Phase Field ◽  
First Principles ◽  
Field Model ◽  
Phase Field Model ◽  
Lithium Ion ◽  
First Principles Calculation ◽  
Li Ion Batteries ◽  
First Principle Calculation ◽  
Dendrite Formation ◽  
Li Ion

Lithium (Li) dendrite formation compromises the reliability of Li-ion batteries, either because dendrite pieces lose electrical contractor or growing dendrite penetrates the separator and leads to internal short-circuiting. In this paper, a multi-scale computational approach integrating phase-field model and first-principles calculation is proposed to predict the Li dendrite formation at the anode/electrolyte interface of Li-ion batteries. The first-principles calculation is employed to atomically determine the interfacial energy, which is subsequently fed into the phase-field model at the micro-scale. 1D distribution of fields is first analyzed to validate the proposed model. An apparent 2D tree-type Li dendrite, widely observed in experiments during electrodeposition, is produced using the model. Finally, the 2D dendritic evolution under different electrochemical conditions specified by the applied current densities is discussed.

scholarly journals The Difference of Lamellar Structure Formation between Ti-45Al-5.4V-3.6Nb-Y Alloy and Ti-44Al-4Nb-4V-0.3Mo-Y Alloy

Metals ◽  
2018 ◽  
Vol 8 (8) ◽  
pp. 566
Author(s):  
Jianchao Han ◽  
Shuzhi Zhang ◽  
Changjiang Zhang ◽  
Fantao Kong ◽  
Yuyong Chen ◽  
...  
Keyword(s):  
Structure Formation ◽  
Phase Field ◽  
Lamellar Structure ◽  
Annealing Temperature ◽  
Volume Fraction ◽  
Common Factor ◽  
Β Phase ◽  
The Common ◽  
The Difference ◽  
Stabilizing Element

In this study, the effect factors on the formation of lamellar structure for Ti-45Al-5.4V-3.6Nb-Y alloy and Ti-44Al-4Nb-4V-0.3Mo-Y alloy is discussed in detail. During heat treatment in different procedures, temperature was the common factor influencing the formation of lamellar structures of Ti-45Al-5.4V-3.6Nb-Y and Ti-44Al-4Nb-4V-0.3Mo-Y alloys. In the range of 1230 °C and 1300 °C, the volume fraction of lamellar structure in Ti-45Al-5.4V-3.6Nb-Y alloy was proportional to the annealing temperature. However, between 1210 °C and 1260 °C, the volume fraction of lamellar structure in Ti-44Al-4Nb-4V-0.3Mo-Y alloy deceased when temperature was located in the α + γ + β triple phase field and then increased when temperature was in the α + β binary phase field. Besides the influence of temperature, the lamellar structure formation of Ti-44Al-4Nb-4V-0.3Mo-Y alloy was also affected by the β-phase stabilizing element.

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