What elements are commonly added to aluminum alloys for strength enhancement?

The addition of copper, magnesium, or zinc to aluminum alloys is a well-established practice for enhancing their strength. These elements contribute to the formation of solid solutions or precipitates within the aluminum matrix, which significantly improve mechanical properties.

Copper, for example, when alloyed with aluminum, leads to improved tensile strength and toughness. It can form intermetallic compounds during heat treatment, which further increases strength. Magnesium is known to enhance corrosion resistance and is commonly used to strengthen aluminum in various alloys, especially those used in marine environments. Zinc also plays a critical role, particularly in the 7000 series of aluminum alloys, where it is used to enhance strength and is often combined with magnesium for better results.

This combination of elements interacts with the base aluminum through processes like age hardening or precipitation hardening, where heat treatment processes allow for the formation of hardening phases that enhance the overall strength of the alloy.

The other options, while they include elements that may interact with aluminum, do not primarily serve to enhance strength in the same effective manner as copper, magnesium, or zinc do. Iron and manganese are typically added for specific purposes such as improving castability or corrosion resistance rather than strength enhancement. Nitrogen and carbon are not commonly associated with aluminum alloys,