Aluminum and aluminum alloys are lightweight compared to steel, brass, and copper, and have high strength-to-weight ratios. They offer good corrosion resistance and conductivity of heat and electricity, as well as moderate formability and machinability. Aluminum alloys include elements that modify the aluminum to achieve specific properties such as better weldability or greater strength. All series of aluminum alloys are nonmagnetic. Aluminum alloys have temper designations, indicating that the material has undergone a process to achieve certain properties of strength and hardness.