Hamburg 2001 – wissenschaftliches Programm

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M: Metallphysik

M 23: Intermetallische Phasen I

M 23.6: Fachvortrag

Mittwoch, 28. März 2001, 16:30–16:45, S5.3

Microstructure and chemistry in nickel aluminide composites reinforced by aliumina-silica fibers — •Weiping Hu and Guenter Gottstein — Institut fuer Metallkunde und Metallphysik der RWTH Aachen

Investigations were carried out on the composites of Ni3Al and NiAl reinforced by alumina-silica fiber (Sumitomo fiber). Electron microscopy (TEM, SEM) and microanalysis (XEDS, EELS and electron diffraction) were employed to study the microstructure development and the chemical stability of the components and their interfaces during diffusion bonding in vacuum. In the Ni3Al composites two different types of chemical reactions were found to occur in the fiber during hot pressing: the reac- tion between nanocrystalline gama-Al2O3 and amorphous SiO2 with the product mullite in the fiber and the reaction at the interface due to with the product alpha-Al2O3 as well as the product NiO in the fiber. In contrast to the Ni3Al composites no Ni diffusion from NiAl matrix into fibre could be detected during diffusion bonding. However, complicated thermodynamic processes have took place in the fibre depending on the temperatures of hot pressing. To interprete the experimental results thermodynamic simulation was carried out. Both results from experiment and thermodynamic simulation were well in consistence.