Aluminum metal matrix composites (MMC) reinforced with
silicon carbide (SiC) particles have up to 20% improvement in
yield strength, have a lower coefficient of thermal expansion
and a higher modulus of elasticity and are more wear resistant
than the corresponding non-reinforced matrix alloy systems
[1,2]. For these reasons they are currently being used in a
number of specialty products. These include break discs made
from castings and bicycle frames made from extrusions.
However, aluminum silicon carbide composites (Al/SiC) are
not accepted for a wide range of applications because of their
low fracture toughness and poor fatigue properties [1–3]. Brittle
interfacial reactions which are lower in strength than the
reinforcing particles may be responsible for the lower fracture
toughness of melt formed MMC [4]. Agglomerations of
particles in MMC provide excellent nucleation points for
fatigue cracks to start. This reduces the fatigue life of Al/SiC
MMC. Both cast and powder metallurgy formed MMC suffer
from agglomeration problems. These toughness and fatigue
properties can be improved by reducing particle agglomeration
and interfacial reactions between the matrix and the reinforcing
particles.