Dresden 2009 – scientific programme

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MM: Fachverband Metall- und Materialphysik

MM 25: Topical Session High Temperature Materials I

MM 25.4: Talk

Wednesday, March 25, 2009, 11:30–11:45, IFW A

Structure, Chemical Stability and Properties of NiAl-Al2O3 Interface Modified by hBN and MAX-Phase Interlayers — •Jia Song, Weiping Hu, Yunlong Zhong, Hao Chen, and Günter Gottstein — Institut für Metallkunde und Metallphysik, Kopernikus Strasse 14, 52056 Aachen, Germany

The interlayers from different materials were used in order to modify the interface structure/property and to improve the mechanical properties of NiAl composites reinforced by continuous single crystal Al2O3 fibers. It was found that the interface without interlayer had a good chemical stability during hot pressing (sample fabricating), resulting in high interface shear strength (about 250 MPa) at RT. But for the composites with interlayers, chemical reactions occurred in the interfacial area during diffusion bonding. In the interfacial area with a hBN interlayer the chemical reaction between BN and NiAl led to the formation of an AlN sublayer and precipitation of nanocrystalline NiAl particles in hBN. The interface shear strength is about 70 MPa. For composites with the V2AlC interlayer, chemical reactions resulted in a complete decomposition of interlayer and formation of varied reaction products. The corresponding interface strength is about 32 MPa. For the case of Cr2AlC interlayer, it was transformed into two sublayers: C-rich sublayer on the fiber side and Cr-rich sublayer next to the matrix. Fine Al2O3 and carbon particles were precipitated in the Cr-rich sublayer and in the Al2O3 fiber respectively. The interfacial shear strength is about 110 MPa. The possible influences by introducing the interlayers on mechanical performance of NiAl composites are discussed.