In Situ Manufacturing of Nano-Particle Reinforced Metal Matrix Composites

Aluminum matrix nano-particle composite materials exhibit promising mechanical and thermal properties such as high specific strength, hardness, stiffness and resistance to creep and thermal degradation. Unfortunately, processing these materials is not easy and numerous attempts have been made to overcome the typical issues associated with their synthesis. These methods include mechanical alloying, powder metallurgy, powder infiltration and spray deposition.(1,2) However, most of these methods are expensive and each one of them has its own limitations. Manufacturing methods that are based on mechanical agitation are cost-effective, but the particles tend to agglomerate because of the excessive Van der Waals forces associated with nano-sized particles. The agglomerated particles can be dispersed by ultrasonic vibrations, but the use of ultrasonic devices on the foundry floor is not practical and the method is not easily scalable.(4) In situ fabrication of the particles in the metal matrix is an answer to many of these challenges. In this method, the nano-sized particles are formed directly within the melt by means of a chemical reaction between a specially designed aluminum alloy and a gas. This paper presents the synthesis of aluminum-aluminum nitride nano-composites by the reaction of a nitrogen containing gas with molten aluminum-lithium alloy.