Composite Materials Research Progress

In: Composite Materials Research Progress ISBN: 1-60021-994-2
Editor: Lucas P. Durand, pp. 275-296 © 2008 Nova Science Publishers, Inc.
Chapter 9
RECENT ADVANCES IN DISCONTINUOUSLY
REINFORCED ALUMINUM BASED METAL MATRIX
NANOCOMPOSITES
S.C. Tjong *
Department of Physics and Materials Science, City University of Hong Kong,
Tat Chee Avenue, Kowloon, Hong Kong
Abstract
Aluminum-based alloys reinforced with ceramic microparticles are attractive materials
for many structural applications. However, large ceramic microparticles often act as stress
concentrators in the composites during mechanical loading, giving rise to failure of materials
via particle cracking. In recent years, increasing demand for high performance materials has
led to the development of aluminum-based nanocomposites having functions and properties
that are not achievable with monolithic materials and microcomposites. The incorporation of
very low volume contents of ceramic reinforcements on a nanometer scale into aluminumbased
alloys yields remarkable mechanical properties such as high tensile stiffness and
strength as well as excellent creep resistance. However, agglomeration of nanoparticles occurs
readily during the composite fabrication, leading to inferior mechanical performance of
nanocomposites with higher filler content. Cryomilling and severe plastic deformation
processes have emerged as the two important processes to form ultrafine grained composites
with homogeneous dispersion of reinforcing particles. In the present review article, recent
development in the processing, structure and mechanical properties of the aluminum-based
nanocomposites are addressed and discussed.
Introduction
Discontinuously reinforced aluminum (DRA) based metal matrix composites are of
increasing interest because of their high specific stiffness and strength, high isotropic and
excellent wear resistance as well as cost effective manufacturing. DRA composites have been
* E-mail address: aptjong@cityu.edu.hk