Tensile Mechanical Properties and Strengthening Mechanism of Hybrid Carbon Nanotube and Silicon Carbide Nanoparticle‐Reinforced Magnesium Alloy Composites

Abstract

AZ91 magnesium alloy hybrid composites reinforced with different hybrid ratios of carbon nanotubes (CNTs) and silicon carbide (SiC) nanoparticulates were fabricated by semisolid stirring assisted ultrasonic cavitation. The results showed that grains of the matrix in the AZ91/(CNT + SiC) composites were obviously refined after adding hybrid CNTs and SiC nanoparticles to the AZ91 alloy, and the room‐temperature mechanical properties of AZ91/(CNT + SiC) hybrid composites were improved comparing with the unreinforced AZ91 matrix. In addition, the tensile mechanical properties of the AZ91 alloy‐based hybrid composites were considerably improved at the mass hybrid ratio of 7 : 3 for CNTs and SiC nanoparticles; in particular, the tensile and yield strength were increased, respectively, by about 45 and 55% after gravity permanent mould casting. The reason for an increase in the room‐temperature strength of the hybrid composites should be mainly attributable to the larger hybrid ratio of CNTs and SiC nanoparticles, the coefficient of thermal expansion (CTE) mismatch between matrix and hybrid reinforcements, the dispersive strengthening effects (Orowan strengthening), and the grain refining (Hall‐Petch effect).