Improved strengthening efficiency of nanoreinforcements realized by a novel melt spinning process
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ARTICLE Improved strengthening efficiency of nanoreinforcements realized by a novel melt spinning process Xiaojun Wang, Hailong Shi, Xiaoshi Hu,a) Linglong Meng, and Kun Wu School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001, China (Received 5 April 2018; accepted 25 May 2018)
Carbon nanotubes (CNTs) and silicon carbide nanoparticle (nano-SiCp)-reinforced magnesium (Mg) matrix hybrid composites were prepared through a three-step melt spinning process (ball milling, mechanical stirring, and ultrasonic vibration processing). The hybrid nanoreinforcements showed high strengthening efficiency by which the yield and tensile strength of the hybrid composites experienced 46.7 and 15.2% increment, respectively, compared with the matrix alloy. Obviously, the mixed ball-milling process of SiC nanoparticles and CNTs promoted the dispersion of each other, and both the uniformly distributed SiC nanoparticles and CNTs contributed to the enhanced mechanical performance of the hybrid composites. Besides, the addition of the hybrid nanoreinforcements induced the precipitation of nanosized rod-like MgZn2 phases in the as-extruded composites which also made a contribution to the enhanced performance of the composites. Investigations on the strengthening mechanisms of the hybrid composites show that it originates from grain refinement, load transfer, precipitation enhancement, and Orowan reinforcing. More importantly, the contribution made by each part was analyzed in detail.
I. INTRODUCTION
With extremely high elastic modulus, super strength, outstanding thermal, and electrical properties, carbon nanotubes (CNTs) are considered as one of the most potential reinforcements for composites since it was found by Iijima in 1991.1,2 Up to now, researchers have done a great amount of work on CNT-reinforced composites. Among them, great success had been acquired mainly on CNT-reinforced polymer composites,3–7 in which CNTs realized uniform distribution in the matrix even with big volume fraction of CNT addition. As for CNT-reinforced metal matrix composites (MMCs/ CNTs), researchers are now facing a few challenges which prevent them from further improving the mechanical properties of the composites8–10: (i) uniform distribution of CNTs in the composites; (ii) strong interfacial bonding between CNTs and the matrix. Normally, because of their nanoscale, it is really difficult to obtain uniform distribution of CNTs in the metal matrix because CNTs are prone to agglomerate with each other by strong Van den Waals force. Although some researchers have tried many methods to disperse CNTs in the composites, large clusters of CNTs formed in the composites once the CNT contents exceeded 2%,14 which limits the reinforcing potential of CNTs in MMCs. Furthermore, strong interface bonding is hard to be obtained due to the poor a)
Address all correspondence to this author. e-mail: [email protected] DOI: 10.1557/jmr.2018.196 J. Mater. Res., 2018
affinity of CNTs with metal matrix. The strong interface bonding is esse
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