Aluminum is usually combined with other elements to form alloys, which are materials that have different properties from the pure metal. Some of the most common alloying elements for aluminum include copper, magnesium, manganese, silicon, and zinc. These elements can be added to aluminum in various proportions to create alloys with specific properties, such as increased strength, hardness, or corrosion resistance. For example, aluminum-copper alloys are often used in aircraft construction due to their high strength and light weight, while aluminum-magnesium alloys are used in automotive applications due to their good corrosion resistance and strength.