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).
Highlights
Magnesium-based composites as a result of their low density and superior mechanical properties are potential candidates for applications in aerospace, automobile, transportation, and consumer industries where weight saving is of great importance [1]
Many attempts have been directed in recent years towards the development of Mg-based composites with nanoparticulates such as Al2O3, Y2O3, silicon carbide (SiC), AlN, and/or carbon nanotubes (CNTs) [2, 3] using different methods such as powder metallurgy, casting, rapid solidification, and in situ fabrication
Investigations carried out by Deng et al [9] illustrated that mechanical properties of AZ91 magnesium matrix composites reinforced with submicron-SiC particulates were improved significantly
Summary
Magnesium-based composites as a result of their low density and superior mechanical properties are potential candidates for applications in aerospace, automobile, transportation, and consumer industries where weight saving is of great importance [1]. Many attempts have been directed in recent years towards the development of Mg-based composites with nanoparticulates such as Al2O3, Y2O3, SiC, AlN, and/or carbon nanotubes (CNTs) [2, 3] using different methods such as powder metallurgy, casting, rapid solidification, and in situ fabrication. Investigations carried out by Deng et al [9] illustrated that mechanical properties of AZ91 magnesium matrix composites reinforced with submicron-SiC particulates were improved significantly. Li et al [10] produced multiwalled carbon nanotube (MWCNT) reinforced magnesium alloy composites with high compressive strength by a predispersing procedure of CNTs on Mg alloy chips followed by a strongly melt stirring technique. Focus is placed in this study to correlate the mechanical properties with the microstructural characteristics due to copresence of SiC nanoparticle and CNT reinforcements. The enhancing mechanism of the hybrid composites is discussed
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