An evaluation of fiber-reinforced titanium matrix composites for advanced high-temperature aerospace applications
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INTRODUCTION
TITANIUM matrix composites (TMCs),ti-q continuously reinforced with silicon carbide (SIC) fibers, are being seriously considered as enabling structural materials in advanced aerospace applications such as high performance turbine engines tS,6j and hypervelocity vehicles, tn Recognizing that the structural limits of more conventional aerospace materials have largely been reached, aircraft and engine designers have turned to TMCs as a potential avenue to significantly increase performance-to-weight capability. In comparison to currently available aerospace titanium and nickel-base alloys, on a density corrected basis, titanium matrix composites appear to offer important advantages in terms of specific strength and stiffness. Moreover, by selective construction of the composite, it appears possible to improve temperature-dependent properties and the resistance to crack growth. The utility of this material system, however, may be dictated by its suitability for the variety of product forms needed by the aerospace industry: for example, nominally unidirectional composite rings and rods to be used in engines and laminated plates and beams needed for aircraft structures.
JAMES M. LARSEN, Research Group Leader, and STEPHAN M. RUSS, Materials Research Engineer, are with the Materials Directorate, Wright Laboratory, Wright-Patterson Air Force Base, OH 45433-7817. J. W. JONES, Professor, is with the Department of Materials Science and Engineering, University of Michigan, Ann Arbor, MI 48109-2136. This article is based on a presentation made in the symposium entitled "Creep and Fatigue in Metal Matrix Composites" at the 1994 TMS/ASM Spring meeting, held February 28-March 3, 1994, in San Francisco, California, under the auspices of the Joint TMS-SMD/ASM-MSD Composite Materials Committee. METALLURGICALAND MATERIALS TRANSACTIONS A
Within the U.S. Air Force, the Integrated High Performance Turbine Engine Technology initiative is the primary force driving the introduction of TMCs in turbine engine components. This initiative, which is funded cooperatively by the U.S. Air Force, Army, Navy, National Aeronautics and Space Administration, and Advanced Research Projects Agency involves research and development by seven major aerospace companies and a variety of government research organizations. The objective of the program is to double turbine engine propulsion capability through an integrated approach in which advanced materials enable innovative structural designs and improved aerothermodynamics to achieve higher thrust-to-weight ratios and lower specific fuel consumption. Although the major payoff from using TMCs comes from rotating components such as structural rings, a variety of rotating and static components are being considered. These applications include turbine engine blades, vanes, stators, actuators, struts, and nozzles, most of which permit the use of unidirectional composite construction. Another force behind the development of TMCs is genetic hypersonic vehicle technology. Technically defined as achi
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