This document discusses metal matrix nanocomposites. It defines nanocomposites as consisting of two phases, with one being nanosized particles embedded in a matrix material. Metal matrix nanocomposites (MMNCs) specifically use a metal as the matrix and a ceramic as the reinforcement. Carbon nanotube metal matrix nanocomposites are also discussed. The document outlines various synthesis routes for fabricating MMNCs, including solid-state and liquid-state processing methods, and discusses some advantages and limitations of different processing techniques. Properties of MMNCs include increased hardness, strength, and superplasticity as well as lowered melting point and improved electrical and magnetic properties.

1. METAL MATRIX NANOCOMPOSITE

2. Composites
• What arecomposites?
• word “composite” means “made of two or
more differentparts.”
•“A composite is a combination of two or more
different materials that are mixed in aneffort to
blendthebestpropertiesof both.”

3. Nanocomposite
• Nanocomposites consist of two
phases (i.e nanocrystalline phase +
matrix phase)
– Phase may be
inorganic-inorganic, inorganic-organic or organic-organic
• Nanocomposite means nanosized particles (i.e metals,
semiconductors, dielectric materials, etc) embedded in
different matrix materials (ceramics, glass, polymers, etc).

4. • Mechanically the term nanocomposites are
differ from conventional composites due to the
exceptionally high surfaceto volume ratio of the
reinforcing and/or its exceptionally high aspect
ratio.
Difference?

5. • consist of one or more discontinuous phases of
distributed in one continuous phase.
• continuous phase is called “matrix”,whereas
discontinuous phase is called “reinforcement" or
“reinforcing material”

6. Nanocomposites can be formed by blending inorganic
nanoclusters, fullerenes, clays, metals, oxides or
semiconductors with numerous organic polymers or organic and
organometallic compounds, biological molecules, enzymes, and sol-
gel derived polymers.
Nanocomposites materials
Latex
Layered silicates
Dispersed nanocomposites

7.  Polymer/Ceramic Nanocomposites
(Layer structure) Eg. Barium-titanate with polymers
 Inorganic/Organic Polymernanocomposites (clusters) Eg.
Polymer nanofiber with zero valent nanoparticles.
 Inorganic/Organic HybridNanocomposites
(Nanocrystal) Eg. CdS nanocrystals, Poly N- vinyl carbozole-
photorefractivity.

8.  Metal/Metal nanocomposites
(either in the form of alloy or core-shell structure)
Eg. Pt-Ru
 Metal/Ceramic nanocomposites (either in the form
of nanotube or complicated nanostructure)
Eg. Polysilazane/polysiloxane
 Ceramic/Ceramic nanocomposites
(alloy orceramic)
Eg. Zirconia-toughenedalumina

9. Metal matrix nanocomposites
• Metal matrix nanocomposites (MMNCs)
comprises of metal as the matrix and ceramic
as the reinforcement.
• This type of composites can be classified as
continuous and non-continuous reinforced
materials.
• Another emerging class of nanocomposites is
Carbon nanotube metal matrix
nanocomposites (CNT-MMNC).

10. Carbon Nanotube Metal Matrix
Nanocomposites
• It provides high tensile strength and electrical conductivity as compared
to carbon nanotube materials.
• Important considerations in the development of processing techniques
of CNT-MMNCs are (a) economically producible, provide a homogeneous
dispersion of nanotubes in the metallic matrix and lead to strong
interfacial adhesion between the metallic matrix and the carbon
nanotubes.
• Apart from CNT-MMNC another important research area of MMNC are
boron nitride reinforced metal matrix composites and carbon nitride
metal matrix composites

11. Synthesis Routes for Fabricating Metal Matrix
Nanocomposites
• Metal matrix Nanocomposites can be processed in the liquid
state or in the solid state. The easiest and cheapest method for
processing nanocomposites are
1. solid state
2. liquid state

12. Solid State Methods
1. Powder Metallurgy (P/M): Powdered metal
and reinforcement are mixed and then
bonded through a process of compaction,
degassing, and thermo-mechanical treatment
(possibly via hot isostatic pressing (HIP) or ex-
trusion).

13. Advantages and limitations of processing methods for
metal-based nanocomposites.
Methods
Spray Pyrolysis
Liquid Infiltration
Limitations
High cost associated with
producing large quantities of
uniform, nanosized particles.
Use of high temperature;
segregation of reinforcements;
formation of undesired products
during processing.
Rapid Solidification
Process (RSP)
Advantages
Effective preparation of ultra fine, spherical and
homogeneous powders in multicomponent
systems, reproductive size and quality.
Short contact times between matrix and
reinforcements; moulding into different and near
net shapes of different stiffness and enhanced
wear resistance; rapid solidification; both lab scale
and industrial scale production.
Simple; effective. Only metal-metal
nanocomposites; induced
agglomeration and non-
homogeneous distribution of
fine particles.
RSP with ultrasonics Good distribution without agglomeration, even
with fine particles.
Homogeneous mixing and uniform distribution.High Energy Ball
Milling
Chemical Processes
(Sol-Gel, Colloidal)
Simple; low processing temperature; versatile;
high chemical homogeneity; rigorous
stoichiometry control; high purity products.
CVD/PVD Capability to produce highly dense and pure
materials; uniform thick films; adhesion at high
deposition rates; good reproducibility
Weak bonding, low wear-
resistance, high permeability
and difficult control of porosity.
Optimization of many
parameters; cost; relative
complexity.

14. Properties of Metal matrix
nanocomposite
• Increased hardness, strength and
superplasticity; Lowered melting point;
• Increased electrical resistivity due to increased disordered grain surfaces;
• Increased miscibility of the non-equilibrium components in alloying
and solid solution;
• Improved magnetic properties such as coercivity, superparamagnetsation,
saturation magnetization and magnetocolatic properties.