Keywords

Alumina, Aluminum, Mechanical alloying, Nanocomposites

Abstract

Aluminum-alumina nanocomposites were synthesized using mechanical alloying of blended component powders of pure constituents. This study was performed on various powder mixtures with aluminum as the matrix and alumina as the reinforcement with volume fractions of 20, 30, and 50 % and Al2O3 particle sizes of 50 nm, 150 nm, and 5 µm. X-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques were used for the crystal structure and microstructural characterization of the powders at different stages of milling. Al2O3 powders with 50 nm and 150 nm particle size were predominantly of γ-type, while Al2O3 of 5 µm size was of α-type. The main goal was to achieve uniform distribution of the Al2O3 ceramic particles in the Al matrix, which was achieved on milling for 24 h in a SPEX mill or 100 h in a Fritsch Pulverisette planetary ball mill. The powders were consolidated in two stages: pre-compaction at room temperature followed by vacuum hot pressing (VHP) or hot isostatic pressing (HIP) techniques to a fully dense condition. The effect of reinforcement particle size and volume fraction on the stress-strain response, elastic modulus and yield strength of the composites was investigated. Nanoindentation and compression tests were performed to characterize the composite material. Yield strength of 515 MPa, compressive strength of 685 MPa and elastic modulus of 36 GPa were obtained from compression tests. Nanoindentation results gave the yield strength of 336 MPa, maximum shear stress of 194 MPa and an elastic modulus of 42 GPa. The low elastic modulus values obtained from the above tests might be because of localized yielding possibly due to residual stresses.

Notes

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Graduation Date

2004

Semester

Summer

Advisor

Suryanarayana, Challapalli

Degree

Master of Science (M.S.)

College

College of Engineering and Computer Science

Department

Mechanical, Materials, and Aerospace Engineering

Degree Program

Materials Science and Engineering

Format

application/pdf

Identifier

CFE0000128

URL

http://purl.fcla.edu/fcla/etd/CFE0000128

Language

English

Release Date

August 2004

Length of Campus-only Access

None

Access Status

Masters Thesis (Open Access)

Subjects

Dissertations, Academic -- Engineering and Computer Science; Engineering and Computer Science -- Dissertations, Academic

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