aeict/2014/131

National Student Conference On “Advances in Electrical & Information Communication Technology”AEICT-2014
Magnesium matrix composite : Challenges and Scope
Adesh kumar1, Vikash mishra2, Hemendra kumar srivastava3
1,2
graduate student, 3Assistant professor
1,2,3
Department of Mechanical Engineering, Pranveer Singh Institute of Technology, Kanpur
1
kumaradesh001gmail.com
2
[email protected]
3
hemendra28@rediff mail.com
Abstract-This paper reviews the state of art concerning powder
metallurgy (P/M) magnesium matrix composites. Among all the
metal matrix composites (MMCs) Magnesium could be the most
widely used metal as matrix due to its low density high strength to
weight ratio and high specific stiffness at both room and elevated
temperature . There are different manufacturing methods which
can be applied for this composite. From these, P/M could be
remarked as a highly effective and economic method compared
with other alternatives.
I. INTRODUCTION
As so far magnesium casting production has experienced an
annual growth of between 10 to 20% over past decades and
expected to continue at this rate [1-3] because of magnesium
alloy or/and magnesium matrix composites have been
increasingly used in automotive industry reason being their
light weight,good damping capacity and superior machinability.
However magnesium alloys/ composites have a relatively low
absolute strength compared to other structural metals, especially
at elevated temperature hence to maintain their strength at high
temperature greater than 120ᵒ C (currently application of AlMg system is limited to 120ᵒ C) Mg matrix composites
unidirectionaly reinforced with continuous carbon fiber those
have superior mechanical properties at elevated temperature of
up to 350-400ᵒ C [4-6-].However fiber/particulate reinforced
composite shows excellent mechanical properties but costly
fabrication technique limit their application areas. Hence cost
effective processing of composites materials is, therefore an
essential element for expanding their application. Since
composite’s properties
depends upon properties of its constituents, geometry and
artitecture of constituents, properties of the boundaries
(interface) between different constituents and also on the
fabrication route. Hence study of these factors is of great
importance for the success of magnesium matrix composites.
This paper reviews recent studies On types of reinforcement,
processing and microstructure of magnesium-matrix composite
II. TYPES OF MMCs
MMCs can be classified into three types depending on the
types of reinforcement.
1.
2.
3.
4.
5.
Particulate-reinforced MMCs
Whisker- or short fiber-reinforced MMCs
Continuous fiber-reinforced MMCs
Mono filament reinforced MMCs
Hybrid MMCs
Some of the salient feature of these three types of MMCs are
detailed below.
2.1. PARTICLE REINFORCED MMCs (PMMCs)
The powder metallurgy (P/M) route for manufacturing
metal matrix composites (MMCs) offers some advantages
compared with ingot metallurgy the main of which is the low
manufacturing temperature that avoids strong interfacial
reaction, minimizing the undesired reactions between the matrix
and the reinforcement In other cases, P/M allows materials to be
obtained which cannot be obtained by any other alternative
route (i.e. SiC reinforcing Ti alloys) Among the various
particulate reinforced, ceramic particles are the most widely
studied reinforcement for magnesium matrix composites
because they have desirable level of hardness, strength, elastic
modulus and thermal stability but have some limitation such as
low ductility. Out of various ceramics reinforcement SiC is the
most popular because of its relatively high wettability and its
stability in magnesium melt as compared to other ceramics
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influence on the strength and other properties of fiber –
reinforced composites .
Figure- 1. Microstructures of magnesium matrix composite having high volume
fraction of Si particle reinforcement (40 vol%)
2.2 WHISKER-REINFORCED AND SHORT FIBER MMCs
(WMMCs)
Figure- 3. Microstructures of continuous fibre-reinforced magnesium matrix
composite
2.4 MONO FILAMENT REINFORCED MMCs (MFMMCs)
Whisker-reinforced composites can be fabricate by powder
metallurgy or infiltration route and shows superior mechanical
properties compared to short fiber or particulate reinforced but
use of whisker reinforced composite has been omitted due to
perceived health hazards hence sort fiber reinforced composite
are being developed increasingly those display charatereristic
between continuous fiber and particle reinforced MMCs .
These monofilament fibers, usually produced by Chemical
vapour deposition of either SiC or B into a core of carbon fiber
or W wire of diameter range 100 to 150µm, those have low
bending flexibility compared to multi -filaments. Monofilament
reinforced composite , usually produced by diffusion bonding
technique , and is limited to super plastic forming magnesium
alloy matrix.
2.5 HYBRID MMCs
Figure-2. Microstructures of short fibre-reinforced magnesium matrix composite
In addition to four types of MMCs described above, another
category of MMCs known as hybrid MMCs have been
developed and are in use to some extent. Hybrid MMCs
essentially contain more than one type of reinforcement. For
example, mixture of particle and whisker, or mixture of fibre
and particle or mixture of hard and soft reinforcements.
Magnesium matrix composite containing mixture of carbon
fibre and magnesium particles used in cylindrical liner
applications is an example of hybrid composite. Figure 1d
shows microstructure of hybrid MMC having both hard SiC and
soft graphite particles as reinforcement
2.3 CONTINOUS FIBER-REINFORCE MMCs (CFMMCs)
These type of composites comprises of reinforcement in the
form of continuous fiber (of SiC or carbon) with diameter less
than 20µm .Fibre orientation and arrangement, fiber
concentratation and the distribution : all have significant
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This process can be categories as liquid-gas, liquid-solid, liquidliquid and mixed salt reactions . in-situ synthesis is a process
wherein the refractory reinforcements are formed in the matrix
by controlled metallurgical reactions. In this process the alloy of
Al–Mg is placed on the top of ceramic preform in a crucible.
The entire assembly is heated to a suitable temperature in the
atmosphere of free flowing nitrogen bearing gas mixture. Al–
Mg alloy soon after melting infiltrates into the preform and
composite is formed.
3.1c SPRAY FORMING
Figure-1. Microstructures of hybrid composite containing 10% SiC and 4%
graphite particles.
III. PROCESSING TECHNIQUES OF MMCs
The selection of processing methods depends on many factors
such as type, level of reinforcement loading and degree of
microstructure integrity desired .
1.
2.
Spray deposition technique can be used by two ways either
droplet stream is produced from a molten bath (Osprey process)
or by continuous feeding of cold metal into a zone of rapid heat
injection (thermal spray process). Spray process permit the
production of continuous fibre reinforced magnesium matrix
Liquid state processes
Solid state processes
Liquid state processes includes stir casting, in-situ(reactive)
processing ,spray deposition whereas solid state process are
powder metallurgy, Diffusion bonding.
3.1a STIR CASTING
stir casting is suitable for manufacturing composites upto 30%
volume fraction . In a stir casting process reinforcement phases
(usually in powder form ) are distributed into molten matrix
phase by mechanical / ultrasonic or electromagnetic / centrifugal
force stirring to overcome the poor wettability between matrix
and reinforcement phase in conventional stir casting method
two-step mixing process have been adapted. In this process the
matrix material is heated to above its liquidus temperature so
that the metal is totally melted . The melt is then cooled down
to a temperature between the liquidus and solidus point and
kept in semi solid state and then pre heated particle are added
and stirred which results a slurry that again heated to form a
completely liquid mixture of matrix and reinforcement.
3.1b IN-SITU PROCESSING ( REACTIVE PROCESSING)
composites but exhibit inhomogeneous distribution of ceramic
particles. Porosity in the as sprayed state is typically about 5–
10%.For continous reinforcement, fibres are wrapped around a
mandrel with controlled inter fibre spacing, and the matrix metal
is sprayed onto the fibres. A composite monotype is thus
formed; bulk composites are formed by hot pressing of
composite monotypes.
3.2a CONVENTIONAL POWDER METALLURGY
In powder metallurgy constituents of composites, both in
powder form are blended, pressed, degassed and sintered at
certain temperature under a controlled atmosphere or in a
vaccum. Blending can be carried out dry or in liquid suspension.
Blending is usually followed by cold compaction, canning,
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National Student Conference On “Advances in Electrical & Information Communication Technology”AEICT-2014
degassing and high temperature consolidation stage such as hot
isostatic pressing (HIP) or extrusion. PM processed MMCs,
contain oxide particles in the form of plate-like particles of few
tens of nm thick and in volume fractions ranging from 0.05 to
0.5 depending on powder history and processing conditions.
These fine oxide particles tends to act as a dispersionstrengthening agent and often has strong influence on the matrix
properties particularly during heat treatment.
Attributes
processes
PM
Microstructural
versatility
Semi continuous
process
Low potential cost
Industrial maturity
1=best
1
Cospray
2
Rheo
casting
2
Liquid
infiltration
2
3
1
1
4
4
1
2
2
1
2
2
4
V. TRENDS OF COST FOR DIFFERENT FORMING
METHODS AND REINFORCEMENT
Table2.
VI.
3.2b DIFFUSION BONDING
Diffusion bonding involves no liquid fusion and The materials
endure no, or very little, plastic deformation; very little residual
stress is introduced; and there is no contamination from the
bonding process. the process is more commonly used to produce
Ti based fibre reinforced composites.
IN table 1 some manufacturing methods for obtaining
composites are compared in terms of some attributes .in table 2
different process and reinforcement are compared in terms of
cost .
IV .RELATIVE CHARACTERISTIC OF DIFFERENT
MANUFACTURING PROCESSES
Table1.
Cost
increasing
ggng
Processes
Diffusion joining
PM
Spray method
Melting process
Reinforcement
Monofilament
Whisker
Short fiber
Particles
CHALLENGES AND OPPORTUNITIES
Several challenges must be overcome in order to intensify the
engineering usage of MMCs. Design, research and product
development efforts and business development skills are
required to overcome these challenges. In this pursuit there is an
imperative need to address the following issues.
1.
2.
3.
4.
5.
6.
Science of primary processing of MMCs need to be
understood more thoroughly, especially factors
affecting the micro-structural integrity including
agglomeration and segregation in MMCs.
There is need to improve the damage tolerant
properties particularly fracture toughness and ductility
in MMCs.
Work should be done to produce high quality and low
cost reinforcements from industrial wastes and byproducts.
Efforts should be made on the development of MMCs
based on non-standard magnesium alloys as matrices.
There is a greater need to classify different grades of
MMCs based on property profile and manufacturing
cost.
There is an urgent need to develop simple, economical
and portable non-destructive kits to quantify
undesirable defects in MMCs.
Department of Electronics & communication Engineering PSIT‖PSIT College of Engineering, Kanpur
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National Student Conference On “Advances in Electrical & Information Communication Technology”AEICT-2014
9. M.K.Jain et aI., The International Journal of Powder
Metallurgy , 29(1993), 267.
Scope of MMCs must be looked as a materials for environment
protection and Energy conservation these two issues must be
sorted at government level. and market acceptance must be
increased by publicizing information about the potential of
MMCs
SUMMARY
A significant amount of time and effort has been devoted to the
research and development of magnesium matrix composites in
recent years. Various techniques have been developed and
applied to the processing of magnesium matrix composites, such
as stir casting, pressure, powder metallurgy and in-situ
formation of reinforcement in the matrix. Key factors affecting
the performance of the magnesium composites are the matrix
composition; the chemistry; the shape, size, and distribution of
the reinforcements; and the bonding strength at the
reinforcement/matrix interface. High strength in the composites
is normally achieved at the cost of compromised ductility.
Nevertheless, grain refinement is an effective way of improving
ductility and strength at ambient temperatures. However,
caution has to be taken in using fine-grained materials at
elevated temperatures because creep resistance can be adversely
affected by the fine grain size. The acceptance of the
magnesium matrix composites as engineering materials depends
not only on the performance advantages of the materials, but
also on the development of cost-effective processing
technologies for these materials.
References
1. EDWARD B. WARDA II , Light Metals Age Feb. (1989) 34.
2. ALAN LUO, JEAN RENAUD, ISAO NAKATSUGAWA
And JACQUES PLOURDE, JOM July (1995) 28.
3. BYRON B. CLOW, Adv. Mater. Proc. Feb./Oct. (1996) 33.
4. PEKGULERYUZ, MIHRIBAN OZDEN and LUO AIHUA
ALAN, Patent WO 96/25529.
5. I. J. POLMER, “Light Alloys,” 2nd edn. Published by
Edward
Arnold (1989) p. 169.
6. F . VON BUCH, J . LIETZAU, B. L. MORDIKE, A.
PISCH and R. SCHMID-FETZER, Mater. Sci. Engng. A 263
(1999) 1.
7. Commercial processing of metal matrix composites
William C. Harrigan Jr. * Alyn Corporation, Irvine, CA 92606, USA
8. X.ZHANG,M.L.TAN ,”Selection of particulate reinforcement in
P/M metal matrix composites “ (School ofMechanical and Production
Engineering, Nanyang Technological University, Nanyang Avenue,
Singapore 639798)
Department of Electronics & communication Engineering PSIT‖PSIT College of Engineering, Kanpur
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