الفهرس 
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Abstract
Powder metallurgy (PM) has grown as a modern technique for the manufacturing of carbon nanotubes (CNTs) reinforced metal matrix composites (MMCs). MMCs have gained importance and considered as future engineering materials. These composite materials are used in various fields such as automotive, aerospace, civil, and other structural fields. Composite materials possess higher specific strength, lower density, better physical, and mechanical properties compared to the base materials.
Aluminum Metal Matrix Composites (Al MMCs) have gained increasing commercial applications over the years. The property of MMCs materials mainly depends on the percentage weight of reinforced material in the base material and the process of developing such composite materials. Al6061 MMCs are quiet popular in engineering applications because of low density and high stiffness. Carbon Nano tube of late, has emerged to be an excellent reinforcement material for Al based MMCs.
This work is focused on study the mechanical and tribological properties of Al6061 reinforced with multi-walled CNTs (MWCNTs) at different weight fractions (wt.%) of 0 , 0.5, 1, and 1.5 under various pressures of 500, 600, and 700 MPa, at various temperatures of 420, 460, and 500 °C. All composites were manufactured by a hot compaction PM technique.
Scanning electron microscope (SEM) was used to investigate samples microstructure to check the distribution of MWCNTs in Al6061matrix alloy. Also, relative density, microhardness, compressive
strength, wear rate, coefficient of friction (COF) and densification of Al6061 and Al6061-MWCNTs composites were examined.
Wear characteristics of the present composites were investigated by pin-on-disc testing machine under the applied load of 30 N, constant sliding speed of 75 m/min, and constant sliding distance of 377 m. The worn surfaces were analyzed using SEM.
The results indicate that the addition of MWCNTs led to improve the relative density, hardness, wear rate, and COF of matrix alloy.
The contribution of this work indicates that:
• Microhardness and wear rate were enhanced at 460 °C under pressure of 600 MPa at 1 wt.% MWCNTs. Also, an enhancement occurred at 1.5 wt.% MWCNTs under 700 MPa.
• All mechanical and tribological properties were improved at 460 °C compared to 420 and 500 °C.
• Compressive strength was increased with increasing of applied pressures up to 700 MPa, while it decreased at low MWCNTs wt.%.
• MWCNTs reinforcement after 1wt.% can be applied in applications that required high compression, hardness, and wear resistance.
• The fracture behavior of the matrix alloy subjects to the fracture behavior of semi-ductile metals, but after adding of reinforcement material, the fracture behavior of the composite behaves like brittle metals.