Student:	Fatih ERDEMİR
Supervisor:	Doç.Dr. Aykut ÇANAKÇI
Department:	Makine Mühendisliği
Institution:	Graduate School of Natural and Applied Sciences
University:	Karadeniz Technical University Turkey

Title of the Thesis:	Production and Characterization of Functionally Graded Al2024/SİC Composites Prepared by Powder
Level:	Ph.D.
Acceptance Date:	15/1/2016
Number of Pages:	130
Registration Number:	Di1113

Summary:

In this study, functionally graded Al2024/SiC composites (FGMs) were produced by powder

metallurgy method. X-ray diffraction (XRD) and scanning electron microscopy (SEM) with

energy-dispersive x-ray spectroscopy (EDX) analyses indicated that Al and SiC were dominant

components as well as others such as Al4C3, CuAl2, and CuMgAl2. A maximum bending strength

of 1400 MPa was obtained for two layered FGMs which contained with 40 wt. % SiC on top layer.

A decrease in microhardness and changes in porozity content were discussed in relation to the SiC

content and the intermetallics formations. The results show that the increase in microhardness

values and intermetallic formation play a major role on the improvement of mechanical properties

of the composites. Al2024 alloy exhibited better toughness compared to those obtained from

Al2024/SiC composites. The corrosion performances of composites were evaluated by

potentiodynamic polarization scans in 3.5 % NaCl solution. Corrosion experiments shows that

corrosion rate (1,109 mpy) of two layered FGMs which containing 50 wt. % SiC were much higher

than Al2024 matrix (2,569 mpy) and Al2024/50 wt.% SiC composite (2,201mpy). Mechanical

properties of these composites were evaluated by microhardness measurements and ball-on-disc

wear tests. As the applied load change from 15 to 20 N, the wear rates of the Al2024 increased

significantly and wear mechanism transformed from mild to severe wear regime. It has been shown

that Al2024/40wt.% SiC composite has lower wear rate where adhesive and abrasive wear

mechanisms play a major role.

Keywords: Metal Matrix Composites, Functionally Graded Materials, Powder Metallurgy,

Intermetallics, Impact Behaviour, Corrosion, Wear.