الفهرس 
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Abstract
The earlier work to evaluate the wear behaviour of
aluminium-silicon alloys has been mainly concerned with the
bearing conditions and silicon content effects. Much of the
needed investigations is the examination of the effects of
certain alloying elements addition into the binary alloys.
Furthermore, the Hear mechanism of the aluminium-based alloys
is a point of controversy and some clearfication is needed.
The present work is an attempt to study the well-known
aluminium-silicon eutectic alloy containing varying copper
addi tions and a constant amount of l-1g and Ni wh i.ch are used
to improve the strength of the eutectic composition. The mate-
rials are prepared by melting the components in a graphite
crucible and pouring them into permanent moulds.
A pin-on-disc type of set up has been designed, fabri-
cated and used for wear test. The specimens are slid against
hardened carbon steel disc of hardness ~ 63 HRe, under various
loads ata relatively high speed of ’” 373 m/min.
Wear rate has been observed by volume losses measure-
-6
ments to be in the range of 10
-7
10 cmJ/cm (volume worn
per unit sliding distance) for the binary eutectic alloy and
10-8 - 10-10 cm 3/cm for alloyed eutectic materials. The wear
rate is identified as being in the range of »mild wear”. The
presence of alloying elements improves the wear resistance
of the binary system, and wear rates are observed to be load
dependent. However I the aging t.r’e a trne nt; of the alloyed materials
did not bring a substantial improvement in the wear resistance.
Mutual transfer is being observed to occur between the
pin and disc surface. The depth of the subsurface damage is
examined and microcracks are shown to be running parallel to
the sliding direction. It is suggested that the wear particles
are formed by two possible delamination modes. The first type
of delamination occurs when the initial surface is ruptured
due to subsurface crack formation and the second by surface
rupture of the back transfer due to the surface force.