Interfacial reaction of BN/Ni3Al

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Abstract
Interfacial reaction between BN and Ni3Al was studied by diffusion bonding at 1000 °C. Error function type diffusion profiles of Ni and Al were observed. Al enrichment at the interface was detected. Kirkendall voids [Trans. Am. Inst. Min. Eng. 1 7 1, 130 (1947)] with faceted interfaces were observed in the interdiffusion zone of Ni3Al side. In situ fractured interface showed a typical heterogeneous interfacial reaction. Three‐dimensional Ni clusters were observed to grow into islands, and unevenly distributed in an alumina matrix of whisker form. The intriguing pattern of the outdiffusion and clustering of Ni atoms, as compared to Al, during the chemical interdiffusion between BN and Ni3Al is discussed based upon grain boundary diffusion, diffusion environment, and thermodynamic driving force under oxygen environment.