BSTS Synthesis Guided by CALPHAD Approach for Phase Equilibria and Process Optimization

2021 ◽  
Author(s):  
Husain Alnaser ◽  
Taylor D. Sparks
Keyword(s):  
Phase Equilibria ◽  
Process Optimization ◽  
Calphad Approach

Thermodynamic Calculations of Phase Equilibria and Phase Fractions of a β-Solidifying TiAl Alloy using the CALPHAD Approach

2012 ◽  
Vol 1516 ◽  
pp. 59-64 ◽  
Author(s):  
Robert Werner ◽  
Martin Schloffer ◽  
Emanuel Schwaighofer ◽  
Helmut Clemens ◽  
Svea Mayer
Keyword(s):  
Phase Equilibria ◽  
Industrial Development ◽  
Tial Alloy ◽  
Thermodynamic Calculations ◽  
Nominal Composition ◽  
Calphad Approach ◽  
Scanning Electron Micrographs ◽  
X Ray Diffraction ◽  
Tial Alloys ◽  
X Ray

ABSTRACTThe CALPHAD (CALculation of PHAse Diagrams) method is widely recognized as a powerful tool in both scientific and industrial development of new materials and processes. For the implementation of consistent databases, where each phase is described separately, models are used which are based on physical principles and parameters assessed from experimental data. Such a database makes it possible to perform realistic calculations of thermodynamic properties of multi-component systems. However, a commercial available TiAl database can be applied for thermodynamic calculations to both conventional Ti-base alloys and complex intermetallic TiAl alloys to describe experimentally evaluated phase fractions as a function of temperature. In the present study calculations were done for a β-solidifying TiAl alloy with a nominal composition of Ti-43.5Al-4Nb-1Mo-0.1B (in at. %), termed TNMTM alloy. At room temperature this alloy consists of ordered γ-TiAl, α2-Ti3Al and β0-TiAl phases. At a certain temperature α2 and β0 disorder to α and β, respectively. Using the commercial database the thermodynamic calculations reflect only qualitative trends of phase fractions as a function of temperature. For more exact quantitative calculations the commercial available thermodynamic database had to be improved for TiAl alloys with high Nb (and Mo) contents, as recently reported for Nb-rich γ-TiAl alloys. Therefore, the database was modified by experimentally evaluated phase fractions obtained from quantitative microstructure analysis of light-optical and scanning electron micrographs as well as conventional X-ray diffraction after long-term heat treatments and by means of in-situ highenergy X-ray diffraction experiments. Based on the CALPHAD-conform thermodynamic assessment, the optimized database can now be used to correctly predict the phase equilibria of this multi-component alloying system, which is of interest for applications in automotive and aircraft engine industry.

Phase Equilibria in the Nb-rich Nb-Ti-Si-Cr-Hf alloys

2011 ◽  
Vol 1295 ◽  
Author(s):  
Ying Yang ◽  
Bernard P. Bewlay ◽  
Austin Chang
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Phase Equilibria ◽  
Calphad Approach ◽  
Rich Region ◽  
Isothermal Sections ◽  
Beneficial Effects ◽  
High Temperature Materials ◽  
Ti Alloys ◽  
Alloying Effects

ABSTRACTRefractory Metal-Intermetallic Composites (RMICs) based on the Nb-Si system have been considered as candidates for the next-generation high temperature materials (i.e. >1200°C). Ti, Cr and Hf have been shown to have beneficial effects on the oxidation resistance and mechanical properties of Nb-Si alloys. The present study has determined phase equilibria in the Nb-rich region of the Nb-Si-Ti-Cr-Hf system via the Calphad approach. The alloying effects of Cr and Hf on the microstructure of Nb-Si-Ti alloys are understood based on isothermal sections, liquidus projections, and solidification curves that were calculated from the thermodynamic models of the Nb-Ti-Si-Cr-Hf system developed in the present study. This work provides important guidelines on the development of new Nb-Si-Ti-Cr-Hf alloys.

scholarly journals Ab initio and CALPHAD-type thermodynamic investigation of the Ti-Al-Zr system

2019 ◽  
Vol 55 (3) ◽  
pp. 427-437 ◽  
Author(s):  
Z.-X. Deng ◽  
D.-P. Zhao ◽  
Y.-Y. Huang ◽  
L.-L. Chen ◽  
H. Zou ◽  
...  
Keyword(s):  
Experimental Data ◽  
Phase Equilibria ◽  
Ab Initio Calculations ◽  
Ab Initio ◽  
Thermodynamic Parameters ◽  
Vertical Section ◽  
Calphad Approach ◽  
Alloying Element ◽  
Formation Enthalpies ◽  
End Members

Ti?Al based alloys have been widely used in the aeronautics and aerospace. Adding alloying element Zr can significantly improve their high-temperature endurance and corrosion resistance. To investigate the influence of the addition of element Zr on the properties of the Ti?Al system, ab initio calculations and the CALPHAD (CALculation of PHAse Diagrams) method were used to evaluate the Ti?Al?Zr ternary system. Ab initio calculations were carried out to calculate the formation enthalpies of intermetallic compounds and end-members. CALPHAD approach was employed to optimize the thermodynamic parameters based on experiments. The experimental data of phase equilibria at 1073, 1273, 1473, and 1573 K, as well as a vertical section of the Ti3Al?Ti + 5 wt.% Zr were used to assess this system. The thermodynamic parameters of the binary Ti?Al, Al?Zr and Ti?Zr systems were acquired from recent assessments, and the ternary ones were evaluated in the present work. The Ti?Al?Zr ternary dataset has been established and the calculated results are in close agreement with the experimental data on both thermodynamics and phase equilibria.

scholarly journals Thermodynamic re-assessment of the Al-Sn-Zn ternary system

2019 ◽  
Vol 55 (3) ◽  
pp. 439-449 ◽  
Author(s):  
T. Cheng ◽  
L.-J. Zhang
Keyword(s):  
Experimental Data ◽  
Ternary System ◽  
Phase Equilibria ◽  
Experimental Phase Equilibria ◽  
Calphad Approach ◽  
Experimental Phase ◽  
Ternary Interaction ◽  
Self Consistent ◽  
Comprehensive Comparison ◽  
Good Agreement

In this paper, a thermodynamic re-assessment of the Al-Sn-Zn ternary system was performed by means of the CALculation of PHAse Diagram (CALPHAD) approach. The thermodynamic descriptions of the binary Al-Sn, Al-Zn, and Sn-Zn systems from the literature were directly adopted, and the newly reported experimental phase equilibria, enthalpies of mixing, and activities of Al in the ternary liquid phase were taken into account. A set of self-consistent thermodynamic parameters for the ternary Al-Sn-Zn system were finally obtained. A comprehensive comparison between the presently calculated phase equilibria/thermodynamic properties and the experimental data indicates that the present thermodynamic descriptions of the ternary Al-Sn-Zn system show very good agreement with most of the experimental data. The further direct comparison with the calculated results due to the previous assessment demonstrates that a significant improvement was achieved by the present assessment though fewer ternary interaction parameters were utilized.

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