The effect of selected oxide ceramic moulds on the contamination of TiAl based alloys

Summary

Until now, no refractory material was found to be absolutely inert against conventional and intermetallic titanium based alloys and some interactions between the molten alloy and the crucible material leading to metal contamination always occur. However, only limited data are available on the effect of reaction time and temperature on oxygen content in TiAl based alloys during their melting and solidification in oxide ceramic moulds.

Objectives

• To study the effect of Al₂O₃and Y₂O₃ moulds on contamination of directionally solidified samples by oxide particles and oxygen at constant growth rates and melt temperatures.
• To study the effect of melt temperature and reaction time on kinetics of contamination by oxygen in samples directionally solidified in Y₂O₃ moulds.

Achievements

• Directional solidification of TiAl based alloy in Al₂O₃ moulds leads to contamination of directionally solidified samples by ceramic particles and oxygen. The ceramic particles are identified to be α-Al₂O₃ phase. The volume fraction of Al₂O₃ particles increases with increasing reaction time and melt temperature. At all melt temperatures, the oxygen content increases with increasing reaction time to a saturated value of about 12000 wt.ppm.
• The ceramic particles formed during directional solidification in Y₂O₃ moulds are identified to be Y₂O₃ phase. The volume fraction of Y₂O₃ particles and oxygen content increase with increasing reaction time and melt temperature. A kinetic equation for contamination by oxygen was determined which allow to predict oxygen content in directionally solidified samples as a function of reaction time and melt temperature.

Additional reading

KLIMOVÁ, A. - LAPIN, J. Effect of oxygen on the microstructure of annealed TiAl based alloy. In ARCHIVESOF MATERIALS SCIENCE AND ENGINEERING, 2014, vol.70, pp. 21-27. (Scopus) ISSN: 1897-2764.

LAPIN, J. - GABALCOVÁ, Z.Solidification behaviour of TiAl-based alloys studied by directional solidification technique. In INTERMETALLICS, 2011, vol.19, pp. 797-804.(IF 1.649) (Current Contents, Scopus, WOS). ISSN 0966-9795.

LAPIN, J. - GABALCOVÁ, Z. - BAJANA, O. The effect of microstructure on mechanical properties of directionally solidified intermetallic Ti-46Al-8Nb alloy. In KOVOVE MATER, 2009, vol.47, pp. 159-167.(Current Contents, WOS, SCOPUS). ISSN 0023-432X.

LAPIN, J. - GABALCOVÁ, Z. The effect of oxygen content and cooling rate on phase transformations in directionally solidified intermetallic Ti-46Al-8Nb alloy. In KOVOVE MATER, 2008, vol.46, pp. 185-195. (Current Contents, WOS, SCOPUS). ISSN 0023-432X.

LAPIN, J. - GABALCOVÁ, Z. - PELACHOVÁ, T. Effect of Y2O3 crucible on contamination of directionally solidified intermetallic Ti-46Al-8Nb alloy. In INTERMETALLICS, 2011, vol.19, pp. 396-403. (IF 1.649) (Current Contents, Scopus, WOS). ISSN: 0966-9795.

GABALCOVÁ, Z. - LAPIN, J. Estimation of high temperature phase equilibria in directionally solidified intermetallic Ti-45.9Al-8Nb alloy. In KOVOVE MATER, 2007, vol.45, pp. 231-240. (IF 1.345) (Current Contents, WOS, SCOPUS). ISSN 0023-432X.

ZOLLINGER, J. - LAPIN, J. - DALOZ, D. - COMBEAU, H. Influence of oxygen on solidification behaviour of cast TiAl-based alloys. In INTERMETALLICS, 2007, vol.15, pp. 1343-1350. (IF 2.219) (Current Contents, Scopus, WOS). ISSN 0966-9795.

LAPIN, J. - ONDRÚŠ, Ľ. - BAJANA, O. Effect of Al2O3 particles on mechanical properties of directionally solidified intermetallic Ti-46Al-2W-0.5Si alloy. In MAT SCI ENG A-STRUCT, 2003, vol.360, pp. 85-95. (IF 1.365) (Current Contents, Scopus, WOS). ISSN 0921-5093.

LAPIN, J. - NAZMY, M. Processing, microstructure and mechanical properties of directionally solidified TiAl based alloy reinforced by Al2O3 particles. In Gamma Titanium Aluminides 2003, 2003, pp. 185-198. (SCOPUS, WOS) ISBN 0-87339-543-3

LAPIN, J. - ONDRÚŠ, Ľ. - NAZMY, M. Directional solidification of intermetallic Ti-46Al-2W-0.5Si alloy in alumina moulds. In INTERMETALLICS, 2002, vol.10, pp. 1019-1031. (IF 1.338) (Current Contents, Scopus, WOS). ISSN 0966-9795.

LAPIN, J. - ONDRÚŠ, Ľ. Formation of ceramic particles in intermetallic Ti-46Al-2W-0.5Si alloy during directional solidification. In KOVOVE MATER, 2002, vol.40, pp. 161-170. (IF 0.493) (Current Contents, WOS, SCOPUS). ISSN 0023-432X.

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