Alloying elements are added to aluminum alloys for a variety of purposes. These alloying elements may affect casting quality or an alloy structure. Therefore, there is a need to control types and forms of the alloying elements for the purpose of improving the casting quality or controlling the alloy structure.
For example, in view of the casting quality, iron may be added for preventing soldering of an aluminum alloy and a die manufactured with an iron-based alloy. However, since iron may decrease corrosion resistance of the aluminum alloy, the addition of iron may also be limited. In this regard, there is a need to prevent the decrease of the corrosion resistance as well as the die soldering by adding iron to the aluminum alloy.
As another example, in view of the alloy structure, heat resistance properties of a typical heat-resistant aluminum alloy may be realized by adding iron or the like to an aluminum matrix to disperse and control intermetallic compounds between aluminum and the alloying elements. These intermetallic compounds may be crystallized in the aluminum matrix during solidification from a liquid phase to a solid phase or may be precipitated in the aluminum matrix by a heat treatment of the aluminum alloy.
However, the heat resistance properties of the above aluminum alloy may deteriorate in an environment of 200° C. or more. In a case where the aluminum alloy is held at 200° C. or more for a long period of time, the crystallized or precipitated intermetallic compounds may react with the aluminum matrix to form new intermediate phases in order for the crystallized or precipitated intermetallic compounds to maintain thermodynamic equilibrium or the generation and propagation of cracks may occur due to the coarsening of such intermetallic compounds.