299
metal-matrix nanocomposites
Metals are the most dominant material used in mechanical applications in any industry. Traditional metallurgy has gone extremely far
in providing designers with an amazing array of high-performance
metals. There are already many superb ways of making metals
stronger (e.g., alloying, work hardening, and dispersion hardening; see Section 4.3). As extensively discussed in Section 7.1, many
extremely high performance alloys are based on nanoscale dispersions of particles. Nano is by no means new to the metallurgist.
Still, there are always demands for stronger, stiffer, or harder materials or materials with particular kinds of stress-strain deformation
characteristics for special applications (e.g., energy absorption).
Metal-matrix nanocomposites provide an improved way of meeting
these needs.
The properties of many common metals can be greatly enhanced
by the addition of relatively small amounts of nanomaterials—normally in the form of nanoparticles, nanowires, and nanotubes. The
basic matrix can be any of several metals or alloys. For many applications, normally a low-weight ductile matrix is desirable. These, in
turn, can be combined with ceramic second-phase reinforcements
that can help increase the modulus and strength values. As discussed in Section 7.8, various metals (aluminum, copper, titanium)
have been reinforced with carbides, borides, nitrides, and oxides.
Depending on the quantity of reinforcement used and the uniformity of distribution, mechanical properties such as strength, wear
resistance, and creep resistance can be adjusted to meet the requirements of the design. Carbon nanotubes (CNTs) have also been used
in metal-matrix nanocomposites, with observed improvements in
yield stress, maximum strength, and hardness. Amounts of secondphase reinforcing used are normally relatively small. Typically,
amounts on the order of 0.5% to 2% of dispersed nanomaterials by
weight can lead to enhancements in mechanical strengths.
Metals such as aluminum are widely used. Aluminum-based metalmatrix composites are extremely interesting because of their low
density and high specific strength. Metal-matrix nanocomposites
are particularly interesting for the aerospace and automotive industries as well as for other structural applications.
Ceramic-matrix nanocomposites
These materials are typically attractive as structural materials for
high-temperature and wear- and corrosion-resistance applications.
In particular, the addition of nanoparticles to a ceramic matrix
Structural and Mechanical Environments
metal-matrix nanocomposites
Metals are the most dominant material used in mechanical applications in any industry. Traditional metallurgy has gone extremely far
in providing designers with an amazing array of high-performance
metals. There are already many superb ways of making metals
stronger (e.g., alloying, work hardening, and dispersion hardening; see Section 4.3). As extensively discussed in Section 7.1, many
extremely high performance alloys are based on nanoscale dispersions of particles. Nano is by no means new to the metallurgist.
Still, there are always demands for stronger, stiffer, or harder materials or materials with particular kinds of stress-strain deformation
characteristics for special applications (e.g., energy absorption).
Metal-matrix nanocomposites provide an improved way of meeting
these needs.
The properties of many common metals can be greatly enhanced
by the addition of relatively small amounts of nanomaterials—normally in the form of nanoparticles, nanowires, and nanotubes. The
basic matrix can be any of several metals or alloys. For many applications, normally a low-weight ductile matrix is desirable. These, in
turn, can be combined with ceramic second-phase reinforcements
that can help increase the modulus and strength values. As discussed in Section 7.8, various metals (aluminum, copper, titanium)
have been reinforced with carbides, borides, nitrides, and oxides.
Depending on the quantity of reinforcement used and the uniformity of distribution, mechanical properties such as strength, wear
resistance, and creep resistance can be adjusted to meet the requirements of the design. Carbon nanotubes (CNTs) have also been used
in metal-matrix nanocomposites, with observed improvements in
yield stress, maximum strength, and hardness. Amounts of secondphase reinforcing used are normally relatively small. Typically,
amounts on the order of 0.5% to 2% of dispersed nanomaterials by
weight can lead to enhancements in mechanical strengths.
Metals such as aluminum are widely used. Aluminum-based metalmatrix composites are extremely interesting because of their low
density and high specific strength. Metal-matrix nanocomposites
are particularly interesting for the aerospace and automotive industries as well as for other structural applications.
Ceramic-matrix nanocomposites
These materials are typically attractive as structural materials for
high-temperature and wear- and corrosion-resistance applications.
In particular, the addition of nanoparticles to a ceramic matrix
Structural and Mechanical Environments