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MM: Fachverband Metall- und Materialphysik

MM 34: Structural Materials II: Brazing and Welding

MM 34.3: Vortrag

Mittwoch, 18. März 2015, 12:00–12:15, TC 010

Diffusion brazing of γ-TiAl-alloys: Investigations by high-energy XRD and electron microscopy — •Katja Hauschildt, Andreas Stark, Peter Staron, Helmut Eckerlebe, Uwe Lorenz, Norbert Schell, Florian Pyczak, and Martin Müller — Helmholtz-Zentrum Geesthacht, Institute of Materials Research, Germany

Diffusion brazing is a promising method to close cracks (in noncritical or non-highly loaded areas) in parts made of TiAl alloy, for example aero engine vanes. In this work the phase constituents, phase distribution, and microstructure of the joint zone of diffusion brazed Ti-45Al-5Nb-0.2B-0.2C (in at. %) alloys are investigated. Two brazing alloys based on Ti-Fe and Ti-Ni are used. The phases and their distribution in the brazing zone were determined by high-energy X-ray diffraction (HEXRD) using the materials science beamline HEMS at the PETRA III synchrotron facility at DESY in Hamburg, Germany. In addition, first in-situ studies of the brazing process were performed. Furthermore, the microstructure was characterised by scanning electron microscopy (SEM) including energy-dispersive X-ray spectroscopy (EDX) and electron backscattered diffraction (EBSD). Additionally, tensile tests at room temperature were carried out. The combined results show, that the brazing zone is composed of two or three transitional layers from substrate material to the middle of the joint. While the phase constitution close to the substrate material resembles a TiAl-alloy, the microstructure in the middle of the joint is similar to α/β-titanium alloys.