scholarly journals Experimental Phase Equilibria and Isopleth Section of 8Nb-TiAl Alloys

Metals ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 1229
Author(s):  
Yong Xu ◽  
Yongfeng Liang ◽  
Lin Song ◽  
Guojian Hao ◽  
Bin Tian ◽  
...  
Keyword(s):  
Thermal Analysis ◽  
Phase Transformation ◽  
Phase Transitions ◽  
Material Design ◽  
Experimental Phase Equilibria ◽  
Intermediate Type ◽  
Calculation Methods ◽  
Experimental Phase ◽  
Tial Alloys ◽  
Low Degree

The 8Nb isopleth section of a Ti-Al-Nb system is experimentally determined based on thermal analysis and thermodynamic calculation methods to obtain the phase transformation and equilibrium relations required for material design and fabrication. The phase transus and relations for the 8Nb-TiAl system show some deviations from the calculated thermodynamic results. The ordered βo phase transforms from the disordered β/α phases at 1200–1400 °C over a large Al concentration range, and this transformation is considered to be an intermediate type between the first- and second-order phase transitions. Moreover, the βo phases are retained at the ambient temperature in the 8Nb-TiAl microstructures. The ωo phase transforms from the highly ordered βo phase, rather than from α2 or βo with a low degree of atom ordering B2 (LOB2) structure, with Al concentration of 32–43 at% at approximately 850 °C. From the experimental detection, the transition of the ωo phase from the βo phase is considered to be a further ordering process.

scholarly journals Experimental Phase Equilibria and Isopleth Section of 8Nb-TiAl Alloys

2021 ◽  
Author(s):  
Yong Xu ◽  
Yongfeng Liang ◽  
Lin Song ◽  
Guojian Hao ◽  
Bin Tian ◽  
...  
Keyword(s):  
Thermal Analysis ◽  
Phase Transformation ◽  
Material Design ◽  
Experimental Phase Equilibria ◽  
Intermediate Type ◽  
Calculation Methods ◽  
Experimental Phase ◽  
Tial Alloys ◽  
Low Degree ◽  
O Phase

The 8Nb isopleth section of a Ti-Al-Nb system is experimentally determined based on thermal analysis and thermodynamic calculation methods to obtain the phase transformation and equilibrium relations required for material design and fabrication. The phase transus and relations for the 8Nb-TiAl system show some deviations from the calculated thermodynamic results. The ordered βo phase transforms from the disordered β/α phases at 1200–1400 °C over a large Al concentration range, and this transformation is considered to be an intermediate type between the first- and second-order phase transitions. Moreover, the βo phases are retained at the ambient temperature in the 8Nb-TiAl microstructures. The ωo phase transforms from the highly ordered βo phase, rather than from α2 or βo with low degree of atom ordering B2 (LOB2) structure, with Al concentration of 32–43 at.% at approximately 850 °C. From the experimental detection, the transition of the ωo phase from the βo phase is considered to be a further ordering process.

Differential Thermal Analysis and Dielectric Studies on Neopentanol under Pressure

1992 ◽  
Vol 47 (11) ◽  
pp. 1127-1134 ◽  
Author(s):  
H. G. Kreul ◽  
R. Waldinger ◽  
A. Würflinger
Keyword(s):  
Thermal Analysis ◽  
Differential Thermal Analysis ◽  
Relaxation Time ◽  
Phase Transitions ◽  
Dielectric Relaxation ◽  
Pressure Dependence ◽  
Dielectric Relaxation Time ◽  
Dielectric Studies ◽  
Dielectric Measurements ◽  
Plastic Phase

Abstract Differential thermal analysis (DTA) and dielectric measurements have been performed on 2,2-dimethyl- 1-propanol (neopentanol) up to 200 MPa. Neopentanol exhibits at least one orientationally disordered (ODIC) phase (solid I) that transforms at lower temperatures to a non-plastic phase (solid II). There is evidence of a further ODIC phase denoted as solid I'. The pressure dependence of the phase transitions and the dielectric behaviour up to frequencies of 13 MHz are described. Activation enthalpies and volumes are derived from the dielectric relaxation time and compared with results for other alcohols

scholarly journals Prediction and measurement of selected phase transformation temperatures of steels

2017 ◽  
Vol 53 (3) ◽  
pp. 391-398 ◽  
Author(s):  
O. Martiník ◽  
B. Smetana ◽  
J. Dobrovská ◽  
A. Kalup ◽  
S. Zlá ◽  
...  
Keyword(s):  
Thermal Analysis ◽  
Phase Transformation ◽  
Statistical Evaluation ◽  
Precise Determination ◽  
Experimental Measurements ◽  
Transformation Temperatures ◽  
Literature Research ◽  
Computational Thermodynamic ◽  
Peritectic Transition

The study deals with precise determination of phase transformation temperatures of steel. A series of experimental measurements were carried out by Differential Thermal Analysis (DTA) and Direct Thermal Analysis (TA) to obtain temperatures very close to the equilibrium temperatures. There are presented results from the high temperatures region, above 1000?C, with focus on the solidus temperatures (TS), peritectic transition (TP) and liquidus (TL) of multicomponent steels. The data obtained were verified by statistical evaluation and compared with computational thermodynamic and empirical calculations. The calculations were performed using 15 empirical equations obtained by literature research (10 for TL and 5 for TS), as well as by software InterDendritic Solidification (IDS) and Thermo-Calc (2015b, TCFE8; TC). It was verified that both thermo-analytical methods used are set correctly; the results are reproducible, comparable and close to equilibrium state.

Modeling Phase Transformation Kinetics and Their Effect on Hardness and Hardness Depth in Laser Hardening of Hypoeutectoid Steel

2015 ◽  
Author(s):  
Suhash Ghosh ◽  
Chittaranjan Sahay
Keyword(s):  
Thermal Analysis ◽  
Phase Transformation ◽  
Phase Transformations ◽  
Laser Hardening ◽  
Temperature History ◽  
Transformation Kinetics ◽  
Continuous Cooling ◽  
Phase Transformation Kinetics ◽  
Hardness Depth ◽  
Hypoeutectoid Steel

Much research has been done to model laser hardening phase transformation kinetics. In that research, assumptions are made about the austenization of the steel that does not translate into accurate hardness depth calculations. The purpose of this paper is to develop an analytical method to accurately model laser hardening phase transformation kinetics of hypoeutectoid steel, accounting for non-homogeneous austenization. The modeling is split into two sections. The first models the transient thermal analysis to obtain temperature time-histories for each point in the workpiece. The second models non-homogeneous austenization and utilizes continuous cooling curves to predict microstructure and hardness. Non-homogeneous austenization plays a significant role in the hardness and hardness depth in the steel. A finite element based three-dimensional thermal analysis in ANSYS is performed to obtain the temperature history on three steel workpieces for laser hardening process with no melting; AISI 1030, 1040 and 1045 steels. This is followed by the determination of microstructural changes due to ferrite and pearlite transformation to austenite during heating and the subsequent austenite to martensite and other diffusional transformations during cooling. Johnson-Mehl-Avrami-Kolmogorov (JMAK) equation is used to track the phase transformations during heating, including the effects of non-homogenous austenitization. The solid state nodal phase transformations during cooling are monitored on the material’s digitized Continuous Cooling Transformation (CCT) curve through a user defined input file in ANSYS for all cooling rates within the Heat Affected Zone (HAZ). Material non-linearity is included in the model by including temperature dependent thermal properties for the material. The model predictions for hardness underneath the laser and the HAZ match well with the experimental results published in literature.

Gate-tunable superconductivity and charge-density wave in monolayer 1T$'$-MoTe$_2$ and 1T$'$-WTe$_2$

2021 ◽  
Author(s):  
Young-Woo Son ◽  
Jun-Ho Lee
Keyword(s):  
Phase Transitions ◽  
Charge Density ◽  
First Principles ◽  
Charge Density Wave ◽  
Density Wave ◽  
Quantum Spin ◽  
First Principles Calculation ◽  
Calculation Methods ◽  
Electron Doping ◽  
Quantum Spin Hall

Using first-principles calculation methods, we reveal a series of phase transitions as a function of gating or electron doping in monolayered quantum spin Hall (QSH) insulators, 1T$'$-MoTe$_2$ and 1T$'$-WTe$_2$. As...

Behavior of thermal properties of AgCu1−xFexS compounds under non-isothermal conditions

2019 ◽  
Vol 33 (28) ◽  
pp. 1950339 ◽  
Author(s):  
Y. I. Aliyev ◽  
P. R. Khalilzade ◽  
Y. G. Asadov ◽  
T. M. Ilyasli ◽  
F. M. Mammadov ◽  
...  
Keyword(s):  
Phase Transition ◽  
Thermal Analysis ◽  
Differential Thermal Analysis ◽  
Thermal Properties ◽  
Phase Transitions ◽  
Structural Phase Transition ◽  
Structural Phase ◽  
Partial Replacement ◽  
Isothermal Conditions ◽  
The Given

AgCu[Formula: see text]Fe[Formula: see text]S compounds were synthesized by partial Cu[Formula: see text][Formula: see text][Formula: see text]Fe replacement in the AgCuS crystal at a concentration range of 0[Formula: see text][Formula: see text][Formula: see text]x[Formula: see text][Formula: see text][Formula: see text]0.03. In the differential thermal analysis spectrum obtained at a temperature range of 300 K[Formula: see text][Formula: see text][Formula: see text]T[Formula: see text][Formula: see text][Formula: see text]1300 K, endoeffect corresponding to the structural phase transition in the AgCuS compound was observed at the temperature T[Formula: see text]=[Formula: see text]938 K. It has been determined that this result is also observed in the AgCu[Formula: see text]Fe[Formula: see text]S compound obtained by partial replacement of Cu atoms by Fe atoms. However, in the compound of AgCu[Formula: see text]Fe[Formula: see text]S this effect was observed at higher temperatures. The thermal capacities and enthalpies of phase transitions were calculated for the given compounds.

Design Approaches and Achievements of Novel Wrought TiAl Alloys for Jet Engine Applications

MRS Advances ◽  
2019 ◽  
Vol 4 (25-26) ◽  
pp. 1465-1470
Author(s):  
Hideki Wakabayashi ◽  
Loris J. Signori ◽  
Ali Shaaban ◽  
Ryosuke Yamagata ◽  
Hirotoyo Nakashima ◽  
...  
Keyword(s):  
Phase Diagram ◽  
Phase Transformation ◽  
Hot Workability ◽  
Tial Alloys ◽  
Jet Engine ◽  
Crack Propagation Resistance ◽  
Β Phase ◽  
Transformation Pathway ◽  
Component Systems ◽  
Multi Component System

AbstractDesign approaches and achievements for the development of wrought TiAl alloys to be used for LPT and HPC blades are constructed. In case of Ti-Al-M1-M2 quaternary systems, conventional equivalency concept does not work for the alloy design, and a new thermodynamic database for phase diagram calculations in multi-component systems of the alloys is built by introducing the interaction parameters among four phases of β−Ti, α2−Ti3Al, α−Ti and γ−TiAl phases in the systems, in order to reproduce the experimentally determined phase diagrams. Based on the phase diagram calculations, the composition range of a unique phase transformation pathway of β+α→α→β+γ in the multi-component system can be identified, and thus model alloys with excellent hot workability even at higher strain rate and mechanical properties can be successfully proposed. It can be concluded that an introduction of bcc β phase and the morphology control through the phase transformation pathway make it possible to improve the room temperature ductility, creep and fatigue crack propagation resistance.

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