Fiber push-out tests on Al2O3 fiber-reinforced NiAl-composites with and without hBN-interlayer at room and elevated temperatures

Fiber push-out tests were performed on continuous Al2O3 fiber-reinforced NiAl-composites with and without hBN-interlayer at room temperature (RT) and elevated temperature (900 °C). The average interfacial shear stress was 248 ± 42 MPa and 72 ± 28 MPa for NiAl/Al2O3 and NiAl/BN/Al2O3 composites at room temperature, respectively. At 900 °C, the push-out tests were aborted for NiAl/Al2O3 composites because of fiber fracture and cracking owing to mechanical twinning on rhombohedral { 1   0   1 ¯   2 } planes in single crystalline Al2O3 fibers, whereas the average interfacial shear stress was 13 ± 7 MPa for NiAl/BN/Al2O3 composites. The debonding position along the interface as well as the initiation of debonding on the top surface of NiAl/Al2O3 and NiAl/BN/Al2O3 composites were determined and discussed. Frictional coefficients of 0.29 and 0.11 for fiber sliding after interface debonding were obtained for NiAl/Al2O3 and NiAl/BN/Al2O3 composites at room temperature, respectively.