Production difficulty, application property requirement and particle size are the three major factors which determine the percentage of reinforcement in metal matrix composites.

It is difficult to produce more than 30 vol.% via stir casting due to issues with mixing, wettability and difficulty in pouring due to increased viscosity of the composite melt. Same number holds good for powder metallurgy route because the composite may become brittle and tear apart during sintering. Squeeze casting can produce more than 50 vol.% due to the application of external pressure and forced infiltration. Friction stir processing can not produce more than 30 vol.% due to the formation of defects because of a reduction in the available matrix material for plasticization to mix with the reinforcement and excessive tool wear. It is hard to produce more than 10 vol.% via accumulative roll bonding because of reduction in contact area to make successive bonding between sheets.

If a component is required to improve wear, say sliding piston, the reinforcement percentage should be carefully chosen to improve the wear resistance. An excessive reinforcement percentage will cause the wear of counter face, say the cylinder liner. The clearance will increase unnecessarily and the purpose of reinforcement will be spoiled. Similarly, one component requires an improved strength say connecting rod. An excess reinforcement will reduce the ductility adversely and make the component to lose its toughness.

Currently, more research is focused on reinforcing nano level particles into composites. A decrease in particle size increases the production difficulty several times. The existing technology can not produce nano particles in excess of 5 vol.% due to exponential increase in the surface of the particle for wetting and an increase in number of particles per vol.% to that of micron sized particle which in turn results in undesirable clustering of particles.

Such a selection is based on existing results on effect of certain kind of a reinforcement (particulate grade, chemical composition, surface properties, etc.) on mechanical properties of the composite material. If such results are absent, preliminary experiments should be performed. Usually, the strongest factor affecting a properties of the composite, is agglomeration level of the reinforcing particulate (and, therefore, the final homogeneity of its dispersion in a metal matrix).

Addition of the reinforcement phase depends on the properties required for specific applications. It is entirely based on the design of composites. One cannot add by simple trial and error method such as 5%, 10%, 15%, 20% and so on. The chosen metal or alloy matrix phase matters too. Both the matrix and reinforcement phase must have affinity to form bonding (physical). Several factors need to be considered. The researcher can refer the previous citations from the literature and decide on this. It entirely depends on the application, type of the matrix phase and the type of the reinforcement chosen. It also necessitates to apply the rule of mixtures.

Dear Dr. Sanjeev Kumar,

the MMCs generally consist of an heterogeneous system where a non-metal phase is dispersed in an alloy.

They can be theoretically customized to specific applications by just changing some qualitative-quantitative parameters of the matrix and of the reinforcing phase.

Such composites, having a lower density than the matrix, generally show higher mechanical properties, which make them economically competitive for special uses (for example in the aeronautical and automotive fields). In these applications indeed, a decrease in density, obviously leads to a lower fuel consumption and higher performances, which is a very important parameter.

However, in order to improve their reliability, their corrosion resistance properties need to be ascertained, through a detailed analysis of the type of material and likely interactions in aggressive environments. In fact, the heterogeneity of the material could compromise its service life owing to corrosion attack.

The characteristics of the composite are strictly linked to different factors: porosity, precipitation of intermetallic phases that can be cathodic in respect to the matrix, formation of reaction products at the matrix-particle interface, matrix composition and characteristics of the reinforcement (type, amount, shape, etc.).

You should have the physical-mechanical characteristics required of your product or a material to refer to and try, acting on concentration, size, dispersion, etc. of your reinforcing particles, to achieve an equal or better result.

Best regards, Pierluigi Traverso

Production difficulty, application property requirement and particle size are the three major factors which determine the percentage of reinforcement in metal matrix composites.

It is difficult to produce more than 30 vol.% via stir casting due to issues with mixing, wettability and difficulty in pouring due to increased viscosity of the composite melt. Same number holds good for powder metallurgy route because the composite may become brittle and tear apart during sintering. Squeeze casting can produce more than 50 vol.% due to the application of external pressure and forced infiltration. Friction stir processing can not produce more than 30 vol.% due to the formation of defects because of a reduction in the available matrix material for plasticization to mix with the reinforcement and excessive tool wear. It is hard to produce more than 10 vol.% via accumulative roll bonding because of reduction in contact area to make successive bonding between sheets.

If a component is required to improve wear, say sliding piston, the reinforcement percentage should be carefully chosen to improve the wear resistance. An excessive reinforcement percentage will cause the wear of counter face, say the cylinder liner. The clearance will increase unnecessarily and the purpose of reinforcement will be spoiled. Similarly, one component requires an improved strength say connecting rod. An excess reinforcement will reduce the ductility adversely and make the component to lose its toughness.

Currently, more research is focused on reinforcing nano level particles into composites. A decrease in particle size increases the production difficulty several times. The existing technology can not produce nano particles in excess of 5 vol.% due to exponential increase in the surface of the particle for wetting and an increase in number of particles per vol.% to that of micron sized particle which in turn results in undesirable clustering of particles.

Literutrue review

Wetability of reinforcement

Temperature you work in

melt Fluidity

Simulation

Reinforcement percentage in MCC is selected based on the application and properties required to enhance, which indirectly depends on the production technique utilized and size of particulate reinforcement. After preparation the MMC can also be subjected to heat treatment for precipitation/age hardening process to enhance the properties. Kindly go through the previously published papers before coming to a conclusion regarding the % of reinforcement to be added.

Dear Sir,

At first, literature review will be the key for rigorous and meticulous research. Secondly, we need to conduct screening tests, to arrive at the best range of the reinforcement weight or volume proportions. Liquid/semi-solid/solid phase of the matrix metal, should not interact more actively with each of the added reinforcement, and should wet each other effectively, to restrict the formation of active and brittle interfacial secondary phases. Hence, selection of an optimal level of reinforcement proportion, is of prime importance.

Dear Sir

you can take some favourable no. of % upto 30-40% and prepare your sample according to the suitable orthogonal array. After preparation, you can conduct all sorts of test on the specimen to get the required % of MgO. May be FEA can be done if all data are available for the composite which you are preparing.

Isaac Dinaharan thank you sir

N. Senthilkumar thank you sir

The quantity of the reinforcement material depends upon the application for which you are fabricating the composites. Based upon the processing route also, it will vary. Generally in case of Stir casting method, 25-30% reinforcement materials can be added. Due to the problems of wettability and difficulty in mixing(agglomeration), more than the above percentage is not favorable. You have also take care about the processing temperature and density of the melt.

The amount of reinforcement percentage depends upon many factors such as hardness, co-efficient of thermal expansion, melting point, density, processing circumstances etc.

This article may be useful

Article Developments in the aluminum metal matrix composites reinfor...

Thank you.

Dear Sanjeev,

From the rule of mixtures, normally, the more reinforcement the better, assuming of course that the reinforcement has better mechanical properties, e.g., better Young's modulus and Ultimate Tensile Stress (UTS), than those of the material of the matrix. In general, the reinforcement volume fraction (ratio of volume of reinforcement-to-composite total volume) is kept between 0.3–0.7 (30–70%), in a trade solution between no reinforcement at all (0%), leading to the low mechanical properties of the matrix, and too much reinforcement, leading to components that cannot be used in structural applications because of problems in the matrix which is unable to fulfil its functions; i.e., with too much reinforcement, there is bad adhesion between the matrix and much of the reinforcement, and the matrix starts to distribute not so effectively the loads among the reinforcement and starts to homogenize not so effectively the strain. Therefore, part of the reinforcement is not working properly and the matrix carries more load than usual, becoming more susceptible to debonding failure mode (undesired failure mode), while the mechanical properties do not increase with increasing quantity of reinforcement because much of it is not working.

The rule of mixtures may be helpful for making a preliminary calculation of the mechanical properties of a composite. For uniaxial/unidirectional laminates (panels with all fibers aligned only in one direction, which is an academic example, since it is not common in industry to use laminates like these), if the following hypotheses apply:

• there is good adhesion between fibers and matrix, meaning that the failure mode will not be due to debonding (and breaking of matrix) but due to breaking of fibers
• the fibers break for a deformation smaller than the deformation corresponding to the yield stress of the matrix
• the Young's modulus of the fibers, Ef, is much higher than that of the matrix, Em

then, from the rule of mixtures, the UTS is approximately equal to Ef·Vf, with Vf being the ratio of volume of fiber-to-total volume of composite (i.e., the fiber volume fraction). The hypotheses mentioned above are usually valid for polymers reinforced with ceramics, but must be considered with a little more caution and on a case-by-case basis for MMC.

Hope this is useful!

Jose

choose the composition of reinforcements as per the literature

Depending on the type of applications percentage of reinforcement is selected

I am working on Mg-based metal matrix composites. I added two different types with a suitable percentage of ceramics separately and tested. Now I want to mix both ceramics in the base metal to make hybrid composites. but, I don't know what percentage of both ceramics to be taken?. Please provide your valuable guidance.

Before going for hybrid composite, these questions to be answered.

1. What is the need of going for hybrid composites?

2. Whether the desired properties can be achieved using a single reinforcement?

3. What is the cost associated with that?

4. What are the difficulties that can be faced during hybrid composite fabrication?

The % reinforcement of different ceramic particulates needs to be identified from the extensive literature survey or through a trial and error procedure method.

The properties desired from an particular application will favor the hybrid % selection.

Thanks [email protected]

As per my recent studies more than 20% of addition of fillers nano powders will lower the property of the composite.