scholarly journals Microstructure Study of Phase Transformation of Quartz in Potassium Silicate Glass at 900 °C and 1000 °C

Crystals ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 1481
Author(s):  
Wenbo Li ◽  
Chenghao Xu ◽  
Ameng Xie ◽  
Ken Chen ◽  
Yingfei Yang ◽  
...  
Keyword(s):  
Phase Transformation ◽  
Interfacial Reaction ◽  
Silicate Glass ◽  
Quartz Glass ◽  
Firing Temperature ◽  
Heterogeneous Nucleation ◽  
Potassium Silicate ◽  
Transformation Rate ◽  
Sio2 Glass ◽  
Glass Interface

Interfacial reaction between quartz and potassium silicate glass was studied at both 900 °C and 1000 °C. The results showed that no phase transformation was observed for the pure quartz at 900 °C or 1000 °C. Instead, for quartz particles in K2O-SiO2 glass, the transformation from quartz to cristobalite occurred at the quartz/glass interface at first, and then the cristobalite crystals transformed into tridymite. The tridymite formed at the interface between particles and glass became the site of heterogeneous nucleation, which induces plenty of tridymite precipitation in potassium silicate glass. The influential mechanism of firing temperature and size of quartz particles on transformation rate was discussed.

scholarly journals Formation of Large Size Precipitate-Free Zones in β Annealing of the Near-β Ti-55531 Titanium Alloy

Metals ◽  
2019 ◽  
Vol 9 (5) ◽  
pp. 544 ◽  
Author(s):  
Xueqi Jiang ◽  
Xiaoqiang Shi ◽  
Xiaoguang Fan ◽  
Qi Li
Keyword(s):  
Titanium Alloy ◽  
Phase Transformation ◽  
Heterogeneous Nucleation ◽  
Isothermal Heat Treatment ◽  
Precipitate Free Zone ◽  
Mode Iii ◽  
Slow Cooling ◽  
Free Zone ◽  
Large Size ◽  
Α Phase

Large size (>10000 μm2) precipitate-free zones in the absence of microsegregation were observed in the near-β Ti-55531 titanium alloy after furnace cooling from high temperature and longtime annealing in the single-β phase field. To reveal the formation mechanism of the large size precipitate-free zone, continuous cooling and isothermal heat treatment were carried out to investigate the β-α phase transformation process. It was found that the large size precipitate free zone is attributed to the heterogeneous nucleation of α phase. The nucleation site evolves in three different modes: I-random nucleation inside the β grain, II-network nucleation inside the β grain and, III-heterogeneous nucleation on the precipitated α phase. Modes I and II lead to homogeneous transformed structure while Mode III results in the large size precipitate-free zone. Both modes II and III are promoted at high annealing temperature, rapid cooling above 600 °C or slow cooling below 600 °C. Mode II is common as it can minimize the strain energy in phase transformation. As a result, the formation of the large size precipitate-free zone is not deterministic.

scholarly journals A mechanism of defect-enhanced phase transformation kinetics in lithium iron phosphate olivine

2019 ◽  
Vol 5 (1) ◽  
Author(s):  
Liang Hong ◽  
Kaiqi Yang ◽  
Ming Tang
Keyword(s):  
Phase Transformation ◽  
Surface Reaction ◽  
Lithium Iron Phosphate ◽  
Active Surface ◽  
Iron Phosphate ◽  
Active Surface Area ◽  
General Strategy ◽  
Transformation Rate ◽  
Kinetic Regime ◽  
Antisite Defects

AbstractAntisite defects are a type of point defect ubiquitously present in intercalation compounds for energy storage applications. While they are often considered a deleterious feature, here we elucidate a mechanism of antisite defects enhancing lithium intercalation kinetics in LiFePO4 by accelerating the FePO4 → LiFePO4 phase transformation. Although FeLi antisites block Li movement along the [010] migration channels in LiFePO4, phase-field modeling reveals that their ability to enhance Li diffusion in other directions significantly increases the active surface area for Li intercalation in the surface-reaction-limited kinetic regime, which results in order-of-magnitude improvement in the phase transformation rate compared to defect-free particles. Antisite defects also promote a more uniform reaction flux on (010) surface and prevent the formation of current hotspots under galvanostatic (dis)charging conditions. We analyze the scaling relation between the phase boundary speed, Li diffusivity and particle dimensions and derive the criteria for the co-optimization of defect content and particle geometry. A surprising prediction is that (100)-oriented LiFePO4 plates could potentially deliver better performance than (010)-oriented plates when the Li intercalation process is surface-reaction-limited. Our work suggests tailoring antisite defects as a general strategy to improve the rate performance of phase-changing battery compounds with strong diffusion anisotropy.

scholarly journals In Situ Neutron Diffraction Study of Phase Transformation of High Mn Steel with Different Carbon Content

Crystals ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 101
Author(s):  
Youngsu Kim ◽  
Wookjin Choi ◽  
Hahn Choo ◽  
Ke An ◽  
Ho-Suk Choi ◽  
...  
Keyword(s):  
Phase Transformation ◽  
Neutron Diffraction ◽  
Strain Hardening ◽  
High Strain ◽  
Tensile Deformation ◽  
Austenite Phase ◽  
Transformation Rate ◽  
Ε Martensite ◽  
In Situ Neutron Diffraction

In situ neutron diffraction was employed to examine the phase transformation behavior of high-Mn steels with different carbon contents (0.1, 0.3, and 0.5 wt.%C). With increasing carbon contents from 0.1 C to 0.5 C, the austenite phase fraction among the constituent phases increased from ~66% to ~98%, and stacking fault energy (SFE) increased from ~0.65 to ~16.5 mJ/m2. The 0.1 C and 0.3 C steels underwent phase transformation from γ-austenite to ε-martensite or α’-martensite during tensile deformation. On the other hand, the 0.5 C steel underwent phase transformation only from γ-austenite to ε-martensite. The 0.3 C steel exhibited a low yield strength, a high strain hardening rate, and the smallest elongation. The high strain hardening of the 0.3 C alloy was due to a rapid phase transformation rate from γ-austenite to ε-martensite. The austenite of 0.5 C steel was strengthened by mechanical twinning during loading process, and the twinning-induced plasticity (TWIP) effect resulted in a large ductility. The 0.5 wt.% carbon addition stabilized the austenite phase by delaying the onset of the ε-martensite phase transformation.

C49-TiSi2 epitaxial orientation dependence of C49-to-C54 phase transformation rate

1998 ◽  
Vol 330 (2) ◽  
pp. 206-210 ◽  
Author(s):  
Kazuto Ikeda ◽  
Hirofumi Tomita ◽  
Satoshi Komiya ◽  
Tomoji Nakamura
Keyword(s):  
Phase Transformation ◽  
Orientation Dependence ◽  
Transformation Rate

Static and dynamics mapping of energy landscape in potassium-silicate glass structure

2005 ◽  
Vol 351 (12-13) ◽  
pp. 1133-1138 ◽  
Author(s):  
Ondrej Gedeon ◽  
Jan Macháček ◽  
Marek Liška
Keyword(s):  
Silicate Glass ◽  
Energy Landscape ◽  
Glass Structure ◽  
Potassium Silicate

C49-TiSi2 Epitaxial Orientation Dependence of the C49-to-C54 Phase Transformation Rate

1998 ◽  
Vol 514 ◽  
Author(s):  
T. Nakamura ◽  
K. Ikeda ◽  
H. Tomita ◽  
S. Komiya ◽  
K. Nakajima
Keyword(s):  
Phase Transformation ◽  
Epitaxial Growth ◽  
Grazing Incidence ◽  
Orientation Dependence ◽  
Transformation Rate ◽  
X Ray Diffraction ◽  
X Ray ◽  
Rapid Transformation

ABSTRACTEffects of the C49-TiSi2 epitaxial orientation on the C49-to-C54 phase transformation rate have been studied for samples with different pre-amorphization implantation (PAI) conditions. The C49 epitaxial orientation to the Si(001) substrate is characterized by use of grazing-incidence X-ray diffraction (GIXD) measurements. We found that the PAl treatment suppresses the epitaxial growth of C49-TiSi2 on Si(001) substrates and the poorer orientational alignment of C49-TiSi2 causes a more rapid transformation to C54-TiSi2. We believe this suppression of epitaxial alignment is a possible mechanism to understand the effect of the PAl treatment on the C49-C54 transformation.

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