THE EFFECT OF PARTICULATE - FIBER RATIO ON THE PROPERTIES OF SHORT-FIBER PARTICULATE HYBRID MMC PRODUCED BY PREFORM INFILTRATION

The details of a novel process for the production of short-fibre/particulate hybrid metal matrix composites (MMC) are presented. It is shown that preforms can be produced from various combinations of particulate and fibre reinforcements, and that these preforms can then be liquid-metal infiltrated to produce hybrid MMC. This process is extremely flexible and can produce materials which vary from conventional hybrids, to composites where the fibre fraction is low and the material is essentially a particulate-reinforced composites. Mechanical property data are presented for these hybrids which show that their strength and elastic moduli appear to be controlled primarily by the total reinforcement volume fraction and not by the particulate: fibre ratio. However, it is shown that this ratio does have a strong influence on the fracture toughness of these hybrid materials.