Interfacial energy issues in ceramic particulate reinforced metal matrix composites

One major scientific issue that needs to be resolved and understood in orde r to design ceramic particle reinforced metal matrix composites is the inte rfacial energy state between the matrix and the reinforcement. Solid-solid interfacial energy between the particle and the matrix effects the final in terface characteristics and also significantly influences the particle redi stribution due to its effect on particle pushing engulfment by the melt int erface. The paper analyses the physics behind the particle pushing and engu lfment by the solidifying interface considering models utilizing interfacia l force as energy difference between the particle in the solid and particle in the liquid melt. Various methods of evaluating solid-solid interfacial energy have been discussed. Velocity of melt interface movement at which th e particles are engulfed by the matrix referred to as critical velocity of the system under given conditions has been shown to be directly related to the interfacial energy. Critical appraisal of experiments to determine the critical velocity have been presented for aluminium matrix dispersed with z irconia particles. Advantages of carrying out experiments under mu g enviro nment have been pointed out.