Abstract
Hybrid nano-(SiCp + TiCp)/Al composites were fabricated by liquid ultrasonic assisted semisolid stirring processing. The eutectic silicon of Al matrix changes from acicular to fine granular with addition of nanoparticles and the dendrite size of primary α-Al decreases with increased nanoparticles. After adding the hybrid nanoparticles with 3 vol%, the minimum average dendrite size can be refined to 30 μm. EDS analysis shows that nano-SiCp and -TiCp particles are uniformly dispersed in Al matrix. The YS and UTS of the composites have reached 200 MPa and 228 MPa, respectively, which are increased by 34.1% and 33.3%, respectively. The elongation of the composites has reached 9.8%, which is increased by 40%. The strengthening mechanism of hybrid nano-(SiCp + TiCp)/Al composites is mainly Orowan strengthening and minorly Hall–Petch strengthening, and the effect of load transfer strengthening is the least.
Highlights
Nanoparticles’ reinforced aluminum matrix composites have been widely used in automotive and aerospace industry
Eutectic silicon phase becomes fine and round without sharp needle-like prominent morphology, and nanoparticles are distributed around eutectic silicon phase; a series of nano-SiCp and -TiCp are distributed in the eutectic silicon phase, which hinders the growth of the eutectic silicon phase [21, 23, 26, 40]
A large number of nano-SiCp and -TiCp are evenly distributed in α-Al matrix
Summary
Nanoparticles’ reinforced aluminum matrix composites have been widely used in automotive and aerospace industry. Wang et al [20–23] studied the effect of nano-TiC0.5N0.5 particles on the microstructure of Al-10Si alloy and found that the use of stirring casting and ultrasonic dispersion of nanoparticles can effectively inhibit the growth of eutectic phase and primary phase, so as to effectively refine the microstructure and improve the mechanical properties of the matrix alloy, especially the elongation. A large number of studies have shown aluminum matrix composites with nanoparticles as reinforcements have stronger comprehensive properties than those with micron particles, and the properties will enhance the tensile and yield strength of the material and improve its toughness and plasticity at the same time [7, 8, 13, 14, 30–38]. Erefore, hybrid nano-(SiCp + TiCp) reinforced A356 alloy matrix composites were prepared by the combination of semisolid stirring and ultrasonic vibration. All results were based on the average of three samples
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