STRUCTURE AND PROPERTIES OF ALIGNED SHORT-FIBER-REINFORCED INTERMETALLIC MATRIX COMPOSITES

Powder injection moulding techniques were utilized to align short fibr es (Al2O3 and SIG) in a variety of intermetallic matrices (NiAl, MoSi2 and TaTiAl2). The alignment was accomplished by extruding a mixture o f powders and short fibres with a polymer-based binder through a const ricting nozzle. The binder was removed and the powder and fibres were consolidated, producing an aligned short fibrous composite. The effect s of powder morphology, fibre volume fraction and fibre diameter on th e alignment were demonstrated. Small diameter powders were required to ensure alignment of an appreciable loading of fibres in a powder matr ix. Tensile and hardness tests were used to evaluate the effectiveness of the aligned short fibres to strengthen and toughen the matrices. T he mechanical behaviour of these aligned short fibrous composites were found to be comparable to similar aligned continuous fibrous composit es produced by conventional techniques.