Synthesis, characterization and properties of stir cast AA6351-aluminium nitride (AlN) composites
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K. Rajan Department of Mechanical Engineering, Dr. MGR Educational & Research Institute University, Chennai 600095, Tamilnadu, India
M. Ravichandran Centre for Research, Chendhuran College of Engineering and Technology, Pudukkottai 622507, Tamil Nadu, India (Received 19 August 2016; accepted 17 November 2016)
In the present investigation, AA6351 aluminum alloy matrix composites reinforced with various percentages of AlN particles were fabricated by stir casting technique. The percentage of AlN was varied from 0 to 20% in a step of 4%. The prepared AA6351-AlN composites were characterized using scanning electron microscope (SEM) and x-ray diffraction (XRD). The mechanical properties such as micro-hardness, compression strength, flexural strength, and tensile strength of the proposed composite have been studied. X-ray diffraction patterns confirm the presence of AlN particles in the composites. SEM analysis reveals the homogeneous distribution of AlN particles in the AA6351 matrix. The mechanical properties of the composite were found to be noticeably higher than that of the plain matrix alloy due to augmented particle content. The produced composites exhibit superior mechanical properties when compared with unreinforced matrix alloy. Fracture surface analysis of tensile specimens show the ductile–brittle nature of failure in the composites.
I. INTRODUCTION
Aluminum based metal matrix composites are continuously replacing traditional engineering materials which have drawn the attention of automotive, aerospace, structural, transportation, and marine industries due to their outstanding combination of high specific strength, high elastic modulus, light weight, high stiffness, and improved wear resistance compared with nonreinforced alloy matrix.1–4 6xxx Al Mg Si alloys are widely used as medium-strength heat-treatable alloys for structural applications due to their excellent formability, weldability, and good corrosion resistance.5 The AA 6351 aluminum alloy is used in ship manufacturing due to its strength, bearing capacity to sea atmosphere, ease of workability, and weldability. It is also used in building boat, column, chimney, rod, mold, pipe, tube, vehicle, bridge, crane, and roof. One of the most important properties of AA 6351 aluminum alloy is that the treatment of solid solution is not so critical.6 As a monolithic, the 6351 Al alloy is used in wrought form where the dendritic structure is removed by hot working. There would be possibilities of the suppression of dendritic Contributing Editor: Jürgen Eckert a) Address all correspondence to this author. e-mail: [email protected] DOI: 10.1557/jmr.2016.460
solidification through ex situ incorporation or in situ generation of particulates during synthesis of 6351 Al based AlMMCs, particularly when the particulates act as the nucleation sites.7 The properties of aluminum matrix composites depend on the type, size, shape, mass fraction, and spatial dispersion of the ceramic particles.8 In recent decades, most of the researchers have been using a wide variety of
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