High-Temperature Interphase Properties of SiC Fiber Reinforced Titanium Metal Matrix Composites.

Abstract : A study has been carried out to determine the high temperature interfacial properties of two titanium metal matrix composites: SCS-6/Timetal-21S and SM1240/Timetal-21S. This report focusses on the effect of temperature on the interfacial shear strength and frictional shear stress of the fiber/matrix interphase. These properties are quantified through the use of 'thin slice' fiber pushout tests, and the numerical determination of residual stresses in the composite system. We discusses the elevated temperature fiber pushout apparatus built for use in this study. Chapter 2 and 3 deal with two aspects of elevated temperature influence: thermal aging and test temperature. The effect of aging on the size and composition of the fiber/matrix interphase is investigated using Scanning Electron Microscopy and Auger Electron Spectroscopy. The experimental work discussed in Chapter 2 relates to samples which were aged at high temperature in air, then cut to the appropriate size. The pushout experiments were conducted at room temperature in an air environment. Chapter 3 focusses on specimens which were aged at high temperature in a vacuum environment, as well as unaged samples. The pushout tests described in this section were conducted either at room and elevated temperatures in both air and vacuum conditions. Chapter 4 examines the influence of process related residual stress on the shear strength of the fiber/matrix interphase using a combined experiment/numerical approach.