Effect of MoSi 2 distribution on room and high temperature mechanical properties of aluminum matrix nanocomposites
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Masoud Emamy and Hassan Farhangi School of Metallurgy and Materials, College of Engineering, University of Tehran, Tehran, Iran (Received 26 February 2016; accepted 25 April 2016)
Nanocomposites of 2024 aluminum–MoSi2 were prepared using mechanical alloying method followed by cold and hot pressing. Influences of volume fraction and distribution of nanosized MoSi2 reinforcement on mechanical properties of the composites were investigated. Microstructural characterization was carried out by scanning electron microscopy and energy dispersive spectroscopy. Mechanical properties of the nanocomposites were evaluated via hardness, wear, and also room and high temperature compression tests. The results showed that although the distribution of low content of MoSi2 nanoparticles in the matrix is homogeneous, with increasing the reinforcement fraction, the tendency of agglomeration is gradually intensified. The addition of reinforcing particles continuously brings a considerable enhancement in the mechanical properties of the matrix alloy but by exceeding a certain amount of the reinforcement fraction, this improvement reduces mainly because of the microstructure inhomogeneity. In addition, the nanocomposite with 3 vol% MoSi2 exhibits the optimum mechanical properties at ambient temperature.
I. INTRODUCTION
Development of the modern technologies creates needs for new construction materials with improved mechanical and physical properties. Aluminum matrix composites (AMCs) are found to be potential materials for many applications in automobile, aerospace, military, and other high technology industries because of high specific strength, good wear resistance, high specific modulus, low coefficient of thermal expansion, and also, good electrical and thermal conductivity.1–4 Extensive studies have been carried out to improve their mechanical properties using different ceramic and intermetallic reinforcing materials such as Al2O3,5 SiC,6 Ni3Al,7 and B4C.8 MoSi2 is a relatively new reinforcement candidate for AMCs due to its high modulus, high wear properties, and thermal stability in the aluminum alloy matrices which have been partially studied in recent years.9–12 A homogeneous distribution of reinforcements is necessary to improve mechanical properties and it is difficult to achieve uniform structure in the case of nanosized particulates. Comprehensive studies have proved that mechanical alloying via ball milling is a suitable technique for this goal and can produce homogeneous microstructures.13–16 Contributing Editor: Jürgen Eckert a) Address all correspondence to this author. e-mail: [email protected] DOI: 10.1557/jmr.2016.190 J. Mater. Res., Vol. 31, No. 12, Jun 28, 2016
In the present work, attempt was made to produce 2024 aluminum alloy matrix nanocomposites with different volume fractions of MoSi2 particles by the use of mechanical alloying technique. The aim is to study the influences of the particle content and distribution on the mechanical properties of the composites and to determine the optimum condition. II. EXPER
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