Casting alloys aluminum-copper

Aluminum casting alloy, major alloying element is copper, have its contents by 4 to 5 %. In addition they contain the usual impurities iron and silicon, and sometimes small amounts of manganese.

The phase diagram of aluminum-copper

These alloys are thermally reinforcing and can reach a relatively high strength and plasticity, particularly if they are derived from ingot with an iron content of not more than 0,15 %.

The phase diagram of aluminum-copper

Single-phase aluminum alloys

Aluminum-copper alloys are single phase. Unlike aluminum-silicon alloys are no secondary phase with a high castability, which is so useful in the final stages of casting solidification. When such a phase is present, it helps to fill the metal voids, that occur during shrinkage, and also compensates for the voltage, that arise in the casting during its solidification.

Hard aluminum alloys

These alloys are more difficult to cast, than, let us say, aluminum silicon alloys with. When you work with them you must take special precautions, to ensure solidification of the metal from the remote stations to the casting hotter and liquid portions, to profits and then to feeders. When such measures are taken due, These aluminum-copper alloys can be successfully used for the production of castings with high strength and ductility. Note, that a more complex molding technology is typical of other single-phase aluminum casting alloys.

Aluminum-copper alloys exhibit very low casting properties and require more careful design of molds, to get a good cast. These alloys are mainly used for sand casting. If there is a need for them in the metal casting mold, then they added to silicon to increase the yield and reduce the hot cracking. However, additions of silicon substantially reduce the ductility of the casting material.

Alloys containing 7-8 % copper

Alloys of aluminum-copper with a higher copper content (7-8 %) were once the most popular. Currently, they are almost completely replaced alloys of aluminum-silicon-copper. The only advantage of the aluminum-copper alloys with high copper content is their insensitivity to impurities. However, they have a very low strength and mediocre casting properties.

Alloys containing 9-11 % copper

It has very limited use of aluminum-copper alloys, which contain 9-11 % copper. They retain high strength at elevated temperatures and have high abrasion resistance, which is very attractive for use in aviation and cylinder heads automotive cylinders blocks.

Very good strength at high temperatures is a characteristic properties of aluminum alloys, which contain copper, nickel and magnesium, and sometimes also iron.

Sources:

Aluminum and Aluminum Alloys, ASM International, 1996

Aluminum Alloy Castings: Properties, Processes And Applications – J. Gilbert Kaufman, Elwin L. Rooy