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Experimental investigations of TiAl-brazes for ceramic joining

: Martin, Hans-Peter; Triebert, Anke

Deutscher Verband für Schweißen und Verwandte Verfahren e.V. -DVS-:
Brazing, high temperature brazing and diffusion bonding. LÖT 2016 : Lectures and posters of the 11th international conference taking place in Aachen on 7th to 9th June 2016
Düsseldorf: DVS Media, 2016 (DVS-Berichte 325)
ISBN: 978-3-945023-64-8
International Conference on Brazing, High Temperature Brazing and Diffusion Bonding (LÖT) <11, 2016, Aachen>
Fraunhofer IKTS ()
brazing; active filler; ceramic joining; high temperature

Ti-Al intermetallics were developed as light weight high temperature alloy. The phase diagram of Ti-Al is well known by several papers [1]. Particularly the -phase of TiAl is preferred because of its ductility and mechanical strength [2, 3]. Meanwhile technical use has started with engineering products made of TiAl [2]. The application as high temperature braze is not mentioned in literature until now. Challenges as high melting point (> 1250°C) and availability of TiAl alloys as brazing material can be overcome in the future. This paper describes an economic preparation method of Ti-Al brazes and first results of joining experiments with alumina, silicon carbide and silicon nitride ceramics. The use of single Al- and Ti foils in combination with the ceramic parts enables the formation of a favorable Ti-Al composition and the TiAl formation at temperatures below 1200°C for successful joining. Brazing experiments between 1200 up to 1500 °C were done to find optimal brazing temperature for different ceramic materials. The Ti-Al composition was varied to produce different Ti-Al phase during the brazing procedure. Phase formation, material structure, thermal effects and mechanical properties of the TiAl braze are investigated and reported. Because of the numerous parameters the development still needs to be completed but first results show promising features of the joint like high temperature strength and oxidation resistance of the braze material.1. H. Okamoto, Al-Ti (Aluminium – Titanium), Journal of Phase Equilibria 14, No.1, section III-Phase Diagram Updates (1993), 1202. H. Clemens, S. Mayer, Design, Processing, Microstructure, Properties, and Applications of Advanced Intermetallic TiAl Alloys, Adv. Eng. Mat. 2012, DOI: 10.1002/adem.2012002313. W.J. Zhang, B.V. Reddy, S.C. Deevi, Scripta Materialia 45 (2001), 645-651