| Popis: |
Today, aluminium is becoming the preferred construction material for transportation applications because it combines three basic properties: strength, durability and lightness. The use of aluminium castings is increasing in a wide range of transport applications. Another advantage of using aluminium materials is their ability to recycle. The use of recycled secondary aluminium alloy has many advantages; it is not only environmentally but also cost-effective. However, the main disadvantage of using a secondary aluminium alloy is the higher amount of iron. Iron in aluminium alloys forms various types of Fe-rich intermetallic phases. It is necessary to control the amount of iron and prediction the formation of undesirable iron intermetallic phases as "sludge" phases, and β-phases. β-phases cause feeding problems, create places with increased concentration of stress, increase casting porosity, and generally reduce plastic properties of the cast alloys. Sludge phases can compromise the machining operations, with a considerable effect on the cutting tool life, and even more degrade the mechanical and physical properties of the component. For the study and identification of intermetallic phases were used equations for calculating SF and critical iron content and observation on the microscope. The results show that coarse sludge, Fe-rich phases appear in the alloy D with 1.200 wt. % Fe. The value critical amount of iron has exceeded in alloy B with 0.679 wt. % Fe, alloy C with 1.209 wt. % Fe, and alloy D with 1.200 wt. % Fe. |
