Effect of Bimodal-Sized Hybrid TiC–CNT Reinforcement on the Mechanical Properties and Coefficient of Thermal Expansion of Aluminium Matrix Composites

Abstract

Aluminium (Al) matrix reinforced with carbon nanotubes (CNT), micron-sized titanium carbide (TiC) particles, and bimodal (nano + micron) hybrid TiC–CNT is fabricated by solution ball milling, followed by cold compaction and vacuum sintering to improve the mechanical properties and reduce thermal expansion. The hardness, wear resistance, compressive strength and CTE of pure Al, 0.6 wt% CNT/Al, 10 wt% TiC/Al, and hybrid 10–0.6 wt% TiC–CNT/Al composites have been investigated in this work. Analysis of strengthening mechanisms based on theoretical models, microstructure, and properties of constituent materials is performed. Microstructure analysis reveals an excellent distribution of the reinforcement phase and no new phase formation in sintered composites. The hardness value of bimodal TiC–CNT reinforced Al composite is significantly higher than monomodal TiC reinforced composite, reaching 2.3 times the hardness value of pure Al. Similarly, the wear resistance improved, and CTE reduced with CNT and TiC addition but is even significantly better in the hybrid reinforced composite. Experimental values of CTE show good agreement with the theoretical model. The strength and ductility of materials are mutually exclusive, but the compressive strength of pure Al has been doubled without significant loss in ductility through the use of bimodal-sized hybrid TiC–CNT reinforcement in this work.