Microstructural and mechanical properties (hardness) investigations of Al-alloyed ductile cast iron

Microstructures and hardness of aluminum alloy ductile iron were investigated by SEM, XRD, EPMA and hardness measurement techniques. The results show, increasing the Al-alloying element leads to decrease of free ferrite and carbide, as well as increase in the pearlite volume fraction. It is also has been found that in the higher values of Al, about 85% of the matrix would be pearlite. It is indicated that an increase in the aluminum content also leads to a decrease in the spacing between pearlite layers. XRD results show, in the presence of Al, intermetallic compounds such as Al6Fe, AlFe3C0.5, Fe3Al and FeAl were produced. Furthermore the hardness measurements illustrate that by increasing the Al content, the microhardness of ferrite and pearlite and specimens hardness have been significantly increased.