Any reaction between reinforcement and the metallic matrix during production will cause the composite vulnerable to tensile loading. The reinforcement and metallic matrix are required to be chemically distinct to call as metal matrix composite (MMC).

The reinforcement particles are mechanically bonded to the metallic matrix in which they are embedded. The interface is the key feature of the MMC which play a crucial role in dictating the properties. One can obtain uniform distribution of reinforcement particles in the composite. But if the interface is weak, the composite will underperform during service.

If MMCs are produced using liquid metallurgy routes such as stir casting, squeeze casting etc. the large difference of coefficient of thermal expansion between reinforcement and metallic matrix would generate large number of strain fields (dislocation density) around the reinforcement particles.

Please refer Chapter 5 of the following book

Nikhilesh Chawla, Krishan K. Chawla, Metal Matrix Composites, Springer, London, 2nd Edition, 2013.

Any reaction between reinforcement and the metallic matrix during production will cause the composite vulnerable to tensile loading. The reinforcement and metallic matrix are required to be chemically distinct to call as metal matrix composite (MMC).

The reinforcement particles are mechanically bonded to the metallic matrix in which they are embedded. The interface is the key feature of the MMC which play a crucial role in dictating the properties. One can obtain uniform distribution of reinforcement particles in the composite. But if the interface is weak, the composite will underperform during service.

If MMCs are produced using liquid metallurgy routes such as stir casting, squeeze casting etc. the large difference of coefficient of thermal expansion between reinforcement and metallic matrix would generate large number of strain fields (dislocation density) around the reinforcement particles.

Please refer Chapter 5 of the following book

Nikhilesh Chawla, Krishan K. Chawla, Metal Matrix Composites, Springer, London, 2nd Edition, 2013.

Thank you so much sir. I am a big follower of you and Murugan sir.  I am using your most of your work as a reference sir. The book was very much useful.

Dear M. Vigneshwar,

Metal matrix can be reinforced with nanoparticles, carbon fibers, whiskers, ceramic particles etc.

Agreeing with Dr. I. Dinaharan, the interface between the metal matrix and reinforcement is of great importance for the success of composite because the load has to be transferred from matrix to reinforcement through the interface.

But in the case of Al and its alloy matrix carbon fibers composites, It is reported that the formation of carbides (Al4C3), in limited amount, in fact, enhanced the strength of the final composites due to the reaction between Al and C. [1]

Other mechanisms that result in the reinforcement include:

*) Dispersion strengthening; due to the uniform dispersion of nanoparticles or carbon fibers (Carbon nanotubes/graphene) of critical size and adequate number density that block the motion of dislocations by Orowan mechanism[2]

*) Grain refinement: The dispersoids (reinforcements) can pin the grain boundaries and preventing from grain coarsening results in Hall-Petch strengthening. [2]

Ref: [1] An analysis of the factors affecting strengthening in carbon nanotube reinforced aluminum composites

http://www.sciencedirect.com/science/article/pii/S0008622310007037

[2] Effect of Carbon Nanotubes as Reinforcement on the Mechanical Properties of Aluminum-Copper-Magnesium Alloy

https://link.springer.com/article/10.1007/s11665-017-2730-7

Anas

Thank you very much Mr.Anas

Thanking you so much sir for sharing kind information regarding reinforcing mechanism of ceramic in metal matrix @ Isaac Dinaharan thank u sir

A reinforcement material (e.g. particulate, fiber) used in a composite material, such as aluminum metal matrix composites (AMMCs), could be ingrained into two mechanisms; chemical and mechanical.

In mechanical perspective, surface roughness of the reinforcement plays a vital role of producing composite materials. In this scenario, hill and valleys of the surface of reinforcement material would be selective side of the composite. The other selective and also contributor side of the composite is the wettability of the matrix material.

In mechanism of the chemical aspect, composites almost "always" needs high temperature to yield best practice/production. Since especially diffusion dynamics and chemical reaction kinetics strongly are addicted higher temperatures, and chemical reactions takes places faster at elevated temperatures, higher processing temperatures are required.

One more thing to say about composite is interface. At the interface of composite material, solid solution and/or intermetallics could be come up. Pay attention of this two type of composite, since both of them exhibit different characteristics (e.g. thermodynamically stable or not).

Regards,

ÇOKY