Microstructure and mechanical properties of continuous Al2O3 fiber reinforced Ni45Al45Cr7.5Ta2.5 alloy (IP75) matrix composites

Yunlong Zhong (1) , David Hajas (2) , Weiping Hu (1) , Hao Chen (1) , Günter Gottstein (1)

1 Institute of Physical Metallurgy and Metal Physics, RWTH Aachen University
2 Materials Chemistry [Aachen]

Single crystalline Al2O3 fibers (Sapphire) coated with the NiAl alloy (IP75) by physical vapor deposition (PVD) were assembled to fabricate composites by means of diffusion bonding. The microstructure and chemistry of both as-coated fiber and as-diffusion bonded composites were investigated by electron microscopy and microanalysis. The interface shear stress for complete debonding was measured by fiber push-out tests at room temperature, and the composite tensile strength was measured at 900 °C and 1100 °C. An amorphous layer with a thickness of about 400 nm formed between the fiber and the matrix during the PVD process and was maintained during diffusion bonding. A Laves phase precipitated along NiAl grain boundaries in the IP75 matrix. This caused a lower tensile strength of the IP75/Al2O3 composite at high temperatures compared to as-cast monolithic IP75 and rendered the composite useless for structural applications.

Mots clés: Physical Sciences

Yunlong Zhong, David Hajas, Weiping Hu, Hao Chen, Günter Gottstein. Microstructure and mechanical properties of continuous Al2O3 fiber reinforced Ni45Al45Cr7.5Ta2.5 alloy (IP75) matrix composites. Philosophical Magazine, 2007, 87 (07), pp.1019-1032. ⟨10.1080/14786430601019458⟩. ⟨hal-00513786⟩