High Fiber Volume Fraction Metal Matrix Composites Cast under Bi-Dimensional Compression

Abstract

This study focuses on a class of metal matrix composites which derive their strength and stiffness from continuous unidirectional fiber reinforcement. The tech nique of bi-dimensional compression was used to fabricate metal matrix composites of this type. The advantage of the technique is its unique bi-dimensional stress field which creates a uniform fiber array and volume fractions approaching the theoretical maximum for rigid fibers. Volume fractions of this magnitude are not readily achievable using conventional fabrication techniques for metal matrix composites without compromising microstructural quality. This study expands previous work with bi-dimensional compression by applying the technique to the fabrication of metal matrix composites. The composites produced in this study were characterized by optical and electron microscopy which allowed qualita tive observation of the fiber distribution, matrix infiltration, void morphology and fiber/matrix interface. Quantitative measures of the quality of the specimens were obtained from fiber volume fraction, density and modulus measurements. The bulk of the speci mens were fabricated in the form of parallelepipeds, which is the shape created by the in terlocking dies of the bi-dimensional compression device. However, the flexibility and ver satility of the technique were demonstrated by the production of circular cylinders and tubes which were reinforced in the longitudinal direction.