Phase Equilibria in the α-Ti-Al-Si Region of the Ti-Si-Al System

Bulanova, M.; Tret'yachenko, L. A.; Golovkova, Marina; Meleshevich, K. A.

doi:10.1361/15477030419478

Cited by 9 publications

(8 citation statements)

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“…Their results did not show the presence of Ti 3 Si phase after isothermal heat-treatment at 973K for 36 days, but the presence of a ternary non-stoichiometric Ti 5 Si 3 phase. In 1997, Bulanova et al 15 also could not identify the presence of Ti 3 Si phase in Ti-13.5Si alloy after heat-treatments at 1323K for 45 hours and 1023K for 58 hours by XRD and microanalysis. The presence of Ti 3 Si phase in a Ti-13.5Si alloy was observed by Ramos et al 16 in 2006 after isothermal heattreatments at 1273K and 1373K for 90 hours by SEM-EDS analysis.…”

Section: Introductionmentioning

confidence: 98%

“…In the light of the dispute over the stability of Ti 3 Si phase in Ti-X-Si engineering alloys [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21] , the present work will calculate and compare the Ti-rich corner of the "stable" and "metastable" Ti-Si phase diagrams, by assuming that Ti 3 Si is the stable phase in the eutectoid reaction, Ti(β)  Ti(α)+ Ti 3 Si. These results will be discussed in order to inspire further experimental work on critical regions of the Ti-Si phase diagram 11 .…”

Section: Introductionmentioning

confidence: 99%

“…It is worth mentioning that most experimental works on the Ti-Si and Ti-Si-X systems [1][2][3][4][5][12][13][14][15][16][17][18][19][20] did not perform chemical analysis of the samples after long isothermal heat-treatments to insure the lack of interstitial contamination. Some of these works, however, were careful enough to apply hardness measurements of control samples (before and after heat-treatments) to audit possible and critical interstitial contamination during the experimental work [1][2][3][4][6][7][12][13][14] .…”

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Assessment of the Ti-Rich Corner of the Ti-Si Phase Diagram: The Recent Dispute About the Eutectoid Reaction

2016

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The thermodynamic optimization of Ti-Si-X systems requires that their respective binary systems are constantly updated. The Ti-Si system has been experimentally investigated since the 1950s and these critical experimental data can be employed to calculate the Ti-Si phase diagram using thermodynamic modeling. The most recent assessment of the Ti-Si system was performed in 1998, showing the presence of stoichiometric Ti 3 Si as stable phase. In the light of the dispute over the stability of Ti 3 Si phase in the eutectoid reaction of the Ti-Si and Ti-X-Si systems, the present work assessed the Ti-rich corner of the "stable" (featuring Ti 3 Si phase) and "metastable" (featuring Ti 5 Si 3 phase) Ti-Si phase diagrams. The phase boundaries, the values of the error of the least-square method of the optimization procedure and the relative standard deviation of the calculated variables of the assessed diagrams; and previous investigations were discussed in order to inspire further experimental work on the eutectoid reaction of the Ti-Si phase diagram.

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Section: Introductionmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

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confidence: 99%

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Assessment of the Ti-Rich Corner of the Ti-Si Phase Diagram: The Recent Dispute About the Eutectoid Reaction

2016

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“…[10] More recently, Liu et al [12] performed differential thermal analysis in a wider range of composition and proposed a reaction scheme that is based on deductions from the succession of thermal events observed on some ternary samples. The systematic study of Bulanova et al [15] was not dealing with the Al-rich corner of the system and even if the authors proposed an extension of reaction scheme in this low temperature range, their results will not be considered here. Zakharov et al [10] performed phase separation in the liquid state by centrifugation in order to analyze the composition of the liquid melt and especially its Ti content.…”

Section: Introductionmentioning

confidence: 99%

On the Liquid/Solid Phase Equilibria in the Al-Rich Corner of the Al-Si-Ti Ternary System

Dezellus

Gardiola

Andrieux

et al. 2014

J. Phase Equilib. Diffus.

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The nature of liquid-solid phase equilibria in the Al-rich corner of the Al-Si-Ti system are determined by drawing three isothermal sections at 620, 680 and 727°C. The solubility of Ti in Al-Si liquids is determined for four different compositions (0, 9, 13 and 18 at.%Si) at temperature below 800°C. Combination of the two sets of experimental results leads to an attempt of liquidus projection. The primary crystallization surface of Al 3 Ti is found to extend up to 9.5 at.%Si in the liquid phase at 620°C and 11 at.%Si at 727°C. The solubility of Ti is found to be not significantly dependent on the Si content of the liquid. From DSC measurements and deduction on microstructure, the last invariant reaction of the solidification path is found to be quasi-peritectic: L

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“…Vale mencionar que boa parte das fases intermediárias dos sistemas binários Si-X são hiper-estequiométricas com relação ao elemento representado por X [9] como, por exemplo, as fases Y5Si3 e V3Si. O sistema ternário Ti-Al-Si foi obtido experimentalmente por Crossley et al [10,11], Schob et al [12], Wu et al [13], Azevedo et al [1,2,14], Bulanova et al [15] e Perrot [16], indicando que o Al era solúvel na fase Ti5Si3. Este sistema foi otimizado termodinamicamente por Azevedo et al [1][2][3], supondo que a fase Ti5Si3 era estequiométrica e sem solubilidade de Al, mas usando uma descrição mais precisa do intermetálico Ti3Al, considerando solubilidade de Si nesta fase.…”

Section: Introductionunclassified

SIMPLIFICAÇÃO DA OTIMIZAÇÃO TERMODINÂMICA DO SISTEMA Ti-Si

Fiore¹,

Neto²,

Azevedo³

2018

ABM Proceedings

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ResumoAs otimizações termodinâmicas de sistema ternários ou de maior ordem contendo titânio necessitam que os sistemas binários Ti-X estejam consistentemente definidos e otimizados. O sistema Ti-Si já foi amplamente estudado e otimizado termodinamicamente. Um dos seus compostos intermediários, a fase Ti5Si3, foi inicialmente considerada estequiométrica nas primeiras otimizações termodinâmicas para facilitar os cálculos, embora os resultados experimentais confirmassem a sua não estequiométrica. A otimização mais recente modelou esta fase como sendo não-estequiométrica com 3 sub-redes. A solubilidade foi considerada em duas das três sub-redes, uma na sub-rede do Si e outra na sub-rede do Ti. O problema dessa abordagem é que ela pode aumentar significativamente o número de variáveis a serem otimizadas no cálculo de sistemas ternários Ti-Si-X, dificultando assim a sua convergência durante processamento computacional. O presente trabalho simplifica a otimização do sistema Ti-Si, considerando que o Ti5Si3 é sempre hiperestequiométrico somente em relação ao Ti. Deste modo, mantêm três sub-redes, mas elimina-se a ocupação do Si na sub-rede do Ti. Os resultados mostram que esta simplificação não afetou significativamente o valor das propriedades termodinâmicas do sistema. Palavras-chave: Ti-Si; Otimização termodinâmica; Thermocalc; Parrot. SIMPLIFICATION OF THE THERMODYNAMIC OPTIMIZATION Ti-Si SYSTEM AbstractThe thermodynamic optimization of ternary or higher order systems containing titanium requires that the Ti binary systems are consistently defined and optimized. The Ti-Si system has been widely studied and optimized thermodynamically. The Ti5Si3 was initially considered stoichiometric to facilitate the thermodynamic calculations, although the experimental results showed that this phase was a nonstoichiometric intermetallic. The most recent optimization of the Ti-Si system described this phase using the sub-lattice model as non-stoichiometric intermetallic containing 3 sublattices. The problem of this approach is that it increases considerably the number of variables to be optimized during the calculation of the TiSi-X phase diagrams, hindering the convergence of the computational processing. The present work simplifies the optimization of the Ti-Si system, assuming that Ti5Si3 is mostly hyper-stoichiometric with respect to Ti. The results show that this simplification does not affect significantly the values of the thermodynamic properties of the system.

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Phase Equilibria in the α-Ti-Al-Si Region of the Ti-Si-Al System

Cited by 9 publications

References 0 publications

Assessment of the Ti-Rich Corner of the Ti-Si Phase Diagram: The Recent Dispute About the Eutectoid Reaction

Assessment of the Ti-Rich Corner of the Ti-Si Phase Diagram: The Recent Dispute About the Eutectoid Reaction

On the Liquid/Solid Phase Equilibria in the Al-Rich Corner of the Al-Si-Ti Ternary System

SIMPLIFICAÇÃO DA OTIMIZAÇÃO TERMODINÂMICA DO SISTEMA Ti-Si

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