THE MECHANISM OF IRON REMOVAL FROM Al-Si ALLOYS BY METALLIC DOPANTS AND CONVERSION OF SILICON PLATELETS

Abstract

The mechanism of iron removal from Al-Si alloys by dopants was studied with the aim of improving the

mechanical and physical properties of the alloys. The mechanism of iron removal from the Al-Si alloys was

established with the results obtained from the study. The as-cast Al-Si alloys were analysed for iron content using

Atomic Absorption Spectrometer technique. The properties tested were the mechanical (ultimate tensile strength,

percentage elongation, microhardness, impact strength and bend test) and physical (electron conductivity and

resistivity) properties. Tensile strength was determined using the TUE-C- 100 Model universal tensile machine,

impact strength was determined using Samuel Denison, Model LS10 2DE impact testing machine, the bend test by

Control Wizard testing machine, Basic Model, microhardness was determined using the Micromet 200 Series

Rockwell testing machine Model 60044 and electron conductivity was determined using DDS-307 conductivity

meter Model Fs240AA.. The results obtained from the study showed that the ratio of iron to dopant equals to 1:1

gave a decrease of iron from 1.7 to 0.44%. It was found that the formation of iron- rich phases such as

Al15(FeMn)3Si2 and Al15(FeCo)4Si2 in preference to AlFeSi phases resulted in iron removal from Al-Si alloys. The

results also showed a correlation between iron removal and mechanical and physical properties.