الفهرس 
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Abstract
Friction stir welding (FSW) is a process which can be used to join aerospace
aluminum alloys and other alloys which can’t be joined with conventional
welding, also it is energy efficient, and environment friendly. Friction Stir
processing (FSP) was developed based on the same principles of friction stir
welding (FSW) mainly to enhance the surface properties of various materials
to produce surface composites, and also increases strength having fine and
homogenous grain structures.
Two types of aluminum alloy were used in this work AA7075 and AA5083,
coarse particle sized Al
2
O
3
and ultrafine sized SiO
2
particles were used as
reinforcement of surface composite, Extensive preliminary work has been
conducted to determine the effect of various processing parameters on the
surface composite quality. These parameters include tool geometry, rotational
speed, traverse speed, and groove dimensions.
In addition, different machines were used to optimize these parameters (e.g.
milling machine and CNC machine). So finally AA7075 was reinforced with
ultrafine size SiO
2
particles to prepare either surface composite or double
surface (i.e. sandwich) composite. And also, AA7075 hybrid surface
composites were prepared using ultra- fine size SiO
2
and Al
2
O
3
particles with
different mixing ratios. These surface composites were developed using FSP
parameters; rotational speed of 600 rpm, traverse speed of 50 mm/min and 3
degrees tilt angle. A groove of 3 mm depth and 1.2 mm width was made on the
surface of matrix. Different tool pin profiles (e.g. cylindrical and square) were
used. These tools were made from K110 tool steel also were heat treated to both
HRC 45 and HRC 60. The previous mentioned work was conducted on friction
welding machine at the friction stir welding and processing laboratory at Suez
University.
The developed surface(s) composites were being evaluated using different
techniques to investigate the macro and micro features. Surface hardness for the developing composite layer increased by 15% to 35%
compared to unprocessed base metal. The groove dimensions provide the
highest reinforcement volume fraction on the produced surface composites,
also the tool dimensions and geometry gave good surface without any defects,
however the squared profile enhanced the reinforcement distribution better than cylindrical one. Moreover, Number of processing paths have effect on surface
composite where the most uniform surface composites achieved by three
consecutive paths. The hybrid surface (SiO
2
and Al
2
O
3
particles/ AA7075)
composites showed enhancement in particle distribution composites and
microhardness measurement compared to AA7075/ SiO
2
surface composites
especially 20% SiO
2
and 80% Al
2
O
3
. In sandwich material the hardness
distribution horizontally is uniform. The current results are consistent with
those from other similar composites reported in the literature.