Title: Fracture behaviour of shallow cryogenically solidified aluminium-alloy reinforced with nano-ZrO₂ metal matrix composites

Authors: Joel Hemanth

Addresses: Mechanical Engineering Department, Rajiv Gandhi Institute of Technology (RGIT), Cholanagar, Hebbal, R.T. Nagar Post, Bangalore-560 032, Karnataka, India

Abstract: Fracture behaviour of LM-13 aluminium alloy reinforced with different wt.% of nano-ZrO₂ particles, solidified under various shallow cryogenically cooled chills (at -80°C), cast using DMD (disintegrated melt deposition) technique followed by hot extrusion were investigated. The size of the particles dispersed varies from 50-80 nm and amount of addition varies from 3 to 15 wt.% in steps of 3 wt.%. Microstructural studies of the nano-composite developed indicate that there is uniform distribution of the reinforcement in the matrix and mechanical properties reveal that presence of nano-ZrO₂ particles as dispersoid (up to12 wt.%) and chill thickness (25 mm) has improved significantly the strength, hardness and fracture toughness with slight reduction in ductility. Fractography of the specimens showed that the fracture behaviour of matrix alloy has changed from ductile intergranular mode to cleavage mode of fracture. Finally heat capacity of the shallow cryo-chill is identified as an important parameter which affects mechanical properties.

Keywords: metal matrix composites; mechanical properties; fracture behaviour; nano ZrO2; zirconium dioxide; zirconia; chill; shallow cryogenic cooling; solidification; microstructure; aluminium alloys; DMD; disintegrated melt deposition; hot extrusion; nanocomposites; nanotechnology; nanoparticles; strength; hardness; fracture toughness; ductility; heat capacity.

DOI: 10.1504/IJMMP.2012.048521

International Journal of Microstructure and Materials Properties, 2012 Vol.7 No.4, pp.301 - 315

Published online: 14 Aug 2012 *

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