Enhancing tensile and compressive strength of magnesium using ball milled Al+CNT reinforcement

Abstract

In this work, Mg/Al–CNT nano-composites were fabricated using powder metallurgy route involving microwave assisted rapid sintering and hot extrusion. Ball milled Al–CNT particles comprising different contents of CNTs coated with fixed amount of Al were used for strengthening. Microstructural characterization of these Mg/Al–CNT nano-composites reveal reasonably uniform distribution of Al–CNT particles up to CNT content of 0.30% by weight, significant grain refinement and the presence of minimal porosity compared to monolithic Mg. Importantly, for the nominally identical processing conditions, the textures of as-extruded nano-composite specimens is significantly influenced by the presence of Al–CNT particles. Nano-composite configurations exhibit different tensile and compressive response as a function of CNT content. Among the different Mg/Al–CNT formulations synthesized, the Mg/Al–CNT configuration with Al–CNT particles composition of 1.00% Al and 0.30% CNT by weight (Mg/1.00Al–0.30CNT) exhibit higher tensile yield strength (0.2% YS), ultimate tensile strength (UTS) and failure strain (FS) (up to +72%, +48%, +9%, respectively) compared to monolithic Mg. In terms of compressive response, it exhibits the best overall compressive properties compared to the monolithic Mg with an improvement of 63% in the compressive yield strength (0.2% CYS) and 80% in ultimate compressive strength (UCS), but failure strain was compromised.