Consolidation of Continuous Fiber, Intermetallic-Matrix Composites
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CONSOLIDATION OF CONTINUOUS FIBER, INTERMETALLIC-MATRIX COMPOSITES S.L. SEMIATIN*, R.L. GOETZ**, AND W.R. KERR* * Materials Directorate, Wright Laboratory, WLJMLLN, Wright-Patterson Air Force Base OH 45433-6533 *UES, Inc., 4401 Dayton-Xenia Road, Dayton OH 45432 ABSTRACT Processing routes for fabrication of continuous fiber, intermetallic-matrix composites are reviewed. These methods include conventional and isostatic hot pressing of layups of matrix material (e.g. foil or powder cloth) and fiber mats; consolidation of monotapes made by techniques such as arc, plasma, vapor, or electron beam deposition or tape casting; and liquid metal infiltration-base methods. The advantages and disadvantages of the various methods are discussed. Particular attention is focussed on HIP consolidation via foil-fiber-foil techniques. Process modeling techniques to assess the effects of pressure, temperature, and time on consolidation behavior are described. By this means, maps to delineate the interaction of process variables in such methods can be developed and applied for process optimization. INTRODUCTION Intermetallic matrix composites represent a relatively new area of engineered materials. The combination of an intermetallic matrix and ceramic reinforcements can provide exceptional levels of room and elevated temperature strength and stiffness as well as low density. Further, tailoring of the fiber-matrix interface properties can enhance composite toughness through control of fiber pullout during fracture. For given matrix and reinforcement materials, the mechanical properties are usually best when the fiber is in a continuous rather than particulate or whisker form. Particulate and whisker reinforced composites can be consolidated and/or shaped via a large number of conventional powder, solidification, or deformation processes. By contrast, the manufacture of continuous-fiber reinforced metal-matrix composites is limited to relatively few methods. Three broad classes of fabrication of continuous-fiber, intermetallic matrix composites have been developed: (1) consolidation of the discrete composite components via hot pressing, (2) consolidation of composite monotapes via hot pressing, and (3) infiltration of liquid (matrix) metal under high pressure into fiber bundles or preforms. Specific methods in each class will be briefly summarized. Following this discussion, one of the more popular approaches under the first category, the foil-fiber-foil technique, will be described. Special emphasis will be placed on the application of process modeling techniques to select consolidation parameters to minimize reaction zone formation, fiber breakage, residual stresses, etc. FABRICATION TECHNIQUES Extensive research and development on fabrication of continuous fiber, intermetallic matrix composites has been in progress for approximately a decade. Unfortunately, much of this work is summarized in limited distribution reports. The Mat. Res. Soc. Symp. Proc. Vol. 273. 01992 Materials Research Society
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