Metal matrix composites reinforced by nano-particles are very promising materials, suitable for a large number of applications. These composites consist of a metal matrix filled with nano-particles featuring physical and mechanical properties very different from those of the matrix. The nano-particles can improve the base material in terms of wear resistance, damping properties and mechanical strength. Different kinds of metals, predominantly Al, Mg and Cu, have been employed for the production of composites reinforced by nano-ceramic particles such as carbides, nitrides, oxides as well as carbon nanotubes. The main issue of concern for the synthesis of these materials consists in the low wettability of the reinforcement phase by the molten metal, which does not allow the synthesis by conventional casting methods. Several alternative routes have been presented in literature for the production of nano-composites. This work is aimed at reviewing the most important manufacturing techniques used for the synthesis of bulk metal matrix nanocomposites. Moreover, the strengthening mechanisms responsible for the improvement of mechanical properties of nano-reinforced metal matrix composites have been reviewed and the main potential applications of this new class of materials are envisaged.

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Metal Matrix Composites Reinforced by Nano-Particles—A Review

Mechanically alloyed nanocomposites

The relative contribution of three strengthening factors in particulate-reinforced metal matrix nanocomposites (MMNCs), namely, load-bearing effect, enhanced dislocation density strengthening effect and Orowan strengthening effect, is evaluated. Orowan strengthening mechanism is found to play a significant role in MMNCs. The relative contribution of Orowan strengthening effect increases with decreasing size of nanoparticles. However, there exists a critical particle size below which the Orowan strengthening effect drops abruptly. The critical particle size, independent of the volume fraction of nanoparticles, is found to be about 5.44 times the magnitude of the Burgers vector of dislocations in the matrix.

Contribution of Orowan strengthening effect in particulate-reinforced metal matrix nanocomposites

This paper summarizes and reviews the state-of-the-art processing methods, structures and mechanical properties of the metal matrix composites reinforced with ceramic nanoparticles. The metal matrices of nanocomposites involved include aluminum and magnesium. The processing approaches for nanocomposites can be classified into ex-situ and in-situ synthesis routes. The ex-situ ceramic nanoparticles are prone to cluster during composite processing and the properties of materials are lower than the theoretical values. Despite the fact of clustering, ex-situ nanocomposites reinforced with very low loading levels of nanoparticles exhibit higher yield strength and creep resistance than their microcomposite counterparts filled with much higher particulate content. Better dispersion of ceramic nanoparticles in metal matrix can be achieved by using appropriate processing techniques. Consequently, improvements in both the mechanical strength and ductility can be obtained readily in aluminum or magnesium by adding ceramic nanoparticles. Similar beneficial enhancements in mechanical properties are observed for the nanocomposites reinforced with in-situ nanoparticles.

Novel Nanoparticle‐Reinforced Metal Matrix Composites with Enhanced Mechanical Properties

https://profdoc.um.ac.ir/articles/a/1023120.pdf

Z. Zhang

Papers

Consideration of Orowan strengthening effect in particulate-reinforced metal matrix nanocomposites: A model for predicting their yield strength

Contribution of Orowan strengthening effect in particulate-reinforced metal matrix nanocomposites