الفهرس 
LITERATURE SURVEYOnly 14 pages are availabe for public view
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Abstract
This thesis aims to study the ability of fabrication of metal
matrix composites using the centrifuged casting technique.
In this work the centrifugal force applied on the molten metal
due to its rotation was used to infiltrate it between the ceramic
free powder.
[AI-A1203] Composite system was chosen to be used in this study,
where both materials are mutually nonreactive. Near eutectic [Al12wt7.Si-2wt7.Mg]alloy
was selected because of its good fluidity
and low melting point. The magnesium was added to enhance the
wettability by limited chemical reaction with the alumina.
In this work a special apparatus was designed and constructed in
order to rotate the specimens, and to allow the molten metal to
infiltrate through the alumina powder along the axis of the
cylindrical specimen.
The processing variables used were as follow:
Rotational speed (N) from 700 to 2000 RPM, Centrifugal pressure
(P) from 0.34 to 6.92 bar, Alumina powder length inside mould
(Lp) from 20 to 60 mm, Powder grain size from 30.8 to 89.8
microns, and Alloy superheat from 20 to 150 K.
It is found that the acting centrifugal pressure (P*) plays the
major role in determining the resulting composite length and
soundness.
An entirely uniform distribution of the alumina particles in the
aluminium matrix was obtained. It was observed that the alumina
particles volume fraction in the resulting composite is always
about 571.. The porosity examinations reveals that the
microporosity increases gradually along the composite length from the specimen end toward the the axis of rotation from 0.2851. to
3.281. by volume and reaches about 5.841. at the metal/composite
interface for the conditions (2000 RPM rotational speed, and 100
K alloy superheat).
The metal/ceramic interface was examined using the scanning
electron microscope, and a line-scann examination across the
interface was made. The effect of both Mg & Si as alloying
elements on the interface quality was also investigated.
Comparing with matrix average hardness (75 VHN), the hardness
measurements indicate an improvement in the composite hardness by
an average value 201.. The maximum measured hardness of the
resulting composite is ( 93.4 VHN) was obtained for the operating
conditions (2000 RPM rotational speed, and 100 K alloy superheat)
in the as cast conditions.