HIGH-FIBER VOLUME FRACTION METAL-MATRIX COMPOSITES CAST UNDER BI-DIMENSIONAL COMPRESSION

This study focuses on a class of metal matrix composites which derive their strength and stiffness from continuous unidirectional fiber rein forcement. The technique of bi-dimensional compression was used to fab ricate metal matrix composites of this type' The advantage of the tech nique is its unique bi-dimensional stress field which creates a unifor m 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 ex pands previous work with bi-dimensional compression by applying the te chnique to the fabrication of metal matrix composites. The composites produced in this study were characterized by optical and electron micr oscopy which allowed qualitative observation of the fiber distribution , matrix infiltration, void morphology and fiber/matrix interface. Qua ntitative measures of the quality of the specimens were obtained from fiber volume fraction, density and modulus measurements. The bulk of t he specimens were fabricated in the form of parallelepipeds, which is the shape created by the interlocking dies of the bi-dimensional compr ession device. However, the flexibility and versatility of the techniq ue were demonstrated by the production of circular cylinders and tubes which were reinforced in the longitudinal direction.