Study on the microstructure and properties of Al-Zn alloy fabricated by sand casting process

Abstract

In this research, the microstructure and properties of aluminium zinc (Al-Zn) alloy with different weight percentage have been studied. This project were carried out by sand casting process. The as-cast sample were prepared by sand casting with different weight percentage of zinc which were 20wt%Zn, 30wt%Zn and 40wt%Zn. The sample then were machined in order to get desired shape and dimensions for testing. The compositions and microstructure of different weight percentage of zinc in aluminum alloys were examined besides mechanical behavior were studied by hardness test, tensile test, porosity and density test. The grain refinement occur when zinc content in aluminium is increased when observed using optical microscope and scanning electron microroscopy. EDX analysis and optical emission spectroscopy shows there were lack of zinc due to the zinc element that were vaporized after mix together with molten aluminium alloys. On the other hand, the mechanical properties of Al-Zn alloys were determined by hardness and tensile test to determine the strength of Al-Zn alloys. The result of hardness test shows that Al-40wt%Zn has the highest hardness value that is 126.74 HV whereas the optimum tensile test for as-cast Al-Zn alloys is Al-30wt%Zn with reading 51.91 N/mm2. Porosity and density test were conducted according to Archimedes Principle. The result shows that density were decrease whereas porosity result was increased.