Improvement of the properties of light metal matrix Micro/Nanocomposite Materials: Myth or reality?

Abstract

The use of materials reinforced by micro-nanoparticles (MMC) is more and more widespread. According to recent studies, the addition of micro-particles in solid materials (polymers, concrete or metal alloys) gives them interesting properties in terms of thermal conductivity, electrical conductivity and mechanical resistance. These properties open new perspectives in terms of environmental consequences. They allow for example to lighten structures while improving their mechanical characteristics, to increase the performance of electrical conductors by reducing energy losses. We provide an example related to light metal alloys widely used in automotive industry and aeronautics. However, the introduction of particles presents several difficulties. The efficiency of particle addition at liquid state depends on many factors, like their dimension, the type of sedimentation forces and the chemical composition of both liquid alloys and particles: (i) at the metallurgical level, the particles are often very reactive and may modify the composition and the micro-structure of the alloy, which can be sometimes beneficial and sometimes damaging, (ii) in terms of scale-up and development of actual processes, the introduction of micro- and especially nanoparticles in liquid phase is a very difficult operation to achieve. Many types of devices are proposed but none is really satisfactory, especially regarding the homogeneity of the materials. We present some application cases related to magnesium alloys that perfectly illustrate the advantages and disadvantages of MMCs.