The behavior of Zr in Ni3Al MMCs reinforced with single crystal Al2O3 fibers

As a part of a study on fiber/matrix interactions in Ni3Al/Al2O3 composites, single crystal Al2O3 (Saphikon) fiber were hot pressed between sheets of Ni3Al that had been modified with zirconium (Oak Ridge National Laboratory designation IC-50). Zirconium has previously been shown to react with alumina fibers in this system, and the extent of that reaction appears to depend on the specific alloying additions to the Ni3Al. In this work, the kinetics of precipitate growth, and compositions at the fiber/matrix interfaces have been studied at temperatures above 1,000 C using Auger Electron Spectroscopy (AES) and Electron Micro-Probe Analysis (EMPA). The mechanical interaction of the fiber with the matrix has been observed by pushing on the fiber ends using a conventional hardness indenter