Improved mechanical properties of Mg matrix composites reinforced with Al and carbon nanotubes fabricated by spark plasm
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Hongbiao Dong Department of Engineering, University of Leicester, Leicester LE1 7RH, UK
Bingshe Xu Key Laboratory of Interface Science and Engineering in Advanced Materials, Ministry of Education, Taiyuan University of Technology, Taiyuan 030024, China; Shanxi Key Laboratory of Advanced Magnesium-based Materials, Taiyuan University of Technology, Taiyuan 030024, China; and Shanxi Research Center of Advanced Materials Science and Technology, Taiyuan 030024, China (Received 15 August 2016; accepted 14 October 2016)
The new processing method of spark plasma sintering (SPS) followed by hot extrusion was developed to produce Mg–1Al–xCNTs composites. Microstructural characterization revealed that the reinforcement particles were distributed uniformly in Mg matrix. The results of mechanical properties indicated a fact that compared with monolithic Mg, all Mg–1Al–xCNTs composites, especially the Mg–1Al–0.15CNTs composite, fabricated by SPS followed by hot extrusion exhibited better tensile and compressive properties. Under tension, Mg–1Al–0.15CNTs composite exhibited higher 0.2% tensile yield strength (TYS) (157 MPa versus 98 MPa, increased by ;60%) and ultimate tensile strength (271 MPa versus 188 MPa, increased by ;44%) than monolithic Mg. In compression, Mg–1Al–0.15CNTs composite also obtained a great enhancement in 0.2% compressive yield strength (118 MPa versus 81 MPa, increased by ;46%) and ultimate compressive strength (321 MPa versus 255 MPa, increased by ;26%) compared to monolithic Mg. Meanwhile, Mg–1Al–0.15CNTs composite maintained a high tensile failure strain of ;8.8% and a high compressive failure strain of ;17.9%.
I. INTRODUCTION
Mg and its alloys are very attractive for numerous applications due to their excellent properties such as high specific strength, low density, etc.1,2 However, the lower mechanical properties of Mg and its alloys compared to steel, iron, and Al alloys have limited their applications. Mg single crystal has a low critical resolved shear stress of about 4.8 MPa and its polycrystal exhibits very low strength and hardness. In addition, Mg and its alloys usually exhibit poor plasticity near room temperature due to the limited number of operative slip systems, resulting from a hexagonal close packed (hcp) crystal structure.3 Therefore, many different technologies have been used to improve the mechanical properties
Contributing Editor: Jürgen Eckert a) Address all correspondence to this author. e-mail: [email protected], [email protected] DOI: 10.1557/jmr.2016.413
of Mg alloys. One method to improve the physical and mechanical properties of Mg alloys is to utilize the effective reinforcements. While the carbon nanotubes (CNTs) with superior strength (30 GPa) and stiffness (1 TPa) are considered one of the most ideal reinforcements for metal matrix composites.4 In recent years, CNTs have attracted considerable attention due to their unique mechanical, electrical, and thermal properties and low density.5 The study on CNTs reinforced Mg and Mg alloy matrix composites has made mu
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