X-ray peak broadening analysis of AA 6061{sub 100-x} - x wt.% Al{sub 2}O{sub 3} nanocomposite prepared by mechanical alloying

Journal Article · Fri Jul 15 00:00:00 EDT 2011 · Materials Characterization

DOI:https://doi.org/10.1016/J.MATCHAR.2011.04.017· OSTI ID:22066373

Sivasankaran, S ^[1]; Sivaprasad, K ^[2]; Narayanasamy, R ^[1]

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1. Department of Production Engineering, National Institute of Technology, Tiruchirappalli-620015 (India)
2. Department of Metallurgical and Materials Engineering, National Institute of Technology, Tiruchirappalli-620 015 (India)

Nanocrystalline AA 6061 alloy reinforced with alumina (0, 4, 8, and 12 wt.%) in amorphized state composite powder was synthesized by mechanical alloying and consolidated by conventional powder metallurgy route. The as-milled and as-sintered (573 K and 673 K) nanocomposites were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The peaks corresponding to fine alumina was not observed by XRD patterns due to amorphization. Using high-resolution transmission electron microscope, it is confirmed that the presence of amorphized alumina observed in Al lattice fringes. The crystallite size, lattice strain, deformation stress, and strain energy density of AA 6061 matrix were determined precisely from the first five most intensive reflection of XRD using simple Williamson-Hall models; uniform deformation model, uniform stress deformation model, and uniform energy density deformation model. Among the developed models, uniform energy density deformation model was observed to be the best fit and realistic model for mechanically alloyed powders. This model evidenced the more anisotropic nature of the ball milled powders. The XRD peaks of as-milled powder samples demonstrated a considerable broadening with percentage of reinforcement due to grain refinement and lattice distortions during same milling time (40 h). The as-sintered (673 K) unreinforced AA 6061 matrix crystallite size from well fitted uniform energy density deformation model was 98 nm. The as-milled and as-sintered (673 K) nanocrystallite matrix sizes for 12 wt.% Al{sub 2}O{sub 3} well fitted by uniform energy density deformation model were 38 nm and 77 nm respectively, which indicate that the fine Al{sub 2}O{sub 3} pinned the matrix grain boundary and prevented the grain growth during sintering. Finally, the lattice parameter of Al matrix in as-milled and as-sintered conditions was also investigated in this paper. Research highlights: {yields} Integral breadth methods using various Williamson-Hall models were investigated for line profile analysis. {yields} Uniform energy density deformation model is observed to the best realistic model. {yields} The present analysis is used for understanding the stress and the strain present in the nanocomposites.

• OSTI ID: 22066373
• Journal Information: Materials Characterization, Vol. 62, Issue 7; Other Information: Copyright (c) 2011 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA); ISSN 1044-5803
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
77 NANOSCIENCE AND NANOTECHNOLOGY
ALUMINIUM OXIDES
AMORPHOUS STATE
COMPOSITE MATERIALS
CRYSTALS
DEFORMATION
ENERGY DENSITY
GRAIN BOUNDARIES
GRAIN GROWTH
GRAIN REFINEMENT
LATTICE PARAMETERS
MILLING
NANOSTRUCTURES
POWDER METALLURGY
POWDERS
SINTERING
STRAINS
STRESSES
TRANSMISSION ELECTRON MICROSCOPY
X-RAY DIFFRACTION