Material Science and Engineering

Biography

Biography: Zong-yi Ma

Abstract

Metal matrix composites with nano-sized reinforcements exhibit better mechanical properties than those with micro-sized particles. However, it is a serious challenge to fabricate the nanocomposites because of the difficult in incorporating the nanoparticles into the metal matrixes. In this study, ex situ carbon nanotubes (CNTs) reinforced 2009Al (CNT/2009Al) and in situ Al₂O₃ and Al₃Ti particles reinforced pure Al(Al₂O₃+Al₃Ti)/Al) composites were fabricated by means of friction stir processing (FSP), a development based on friction stir welding. It was indicated that FSP could break up the CNT clusters and achieve uniform individual distribution of CNTs and induce in situ reaction between TiO₂ and Al, forming Al₂O₃ and Al₃Ti nanoparticles. The mechanisms responsible for the dispersion and damage of CNTs and the accelerated reaction between Ti and Al were analyzed in detail. It was indicated that although CNTs were cut short during FSP, the layer structure of CNTs was well retained. The formation mechanisms of Al₂O₃ and Al₃Ti during FSP were determined to be a deformation-assisted interfacial reaction and deformation-assisted solution-precipitation, respectively. The CNT/2009Al and (Al₂O₃+Al₃Ti)/Al composites exhibited a good combination of strength and ductility. This investigation provides a new route to fabricate high-property nanocomposites.