Aluminum - Aluminum is remarkable for the metal's low density and for its ability to resist corrosion due to the phenomenon of passivation. In addition, aluminum has good electrical and thermal conductivities, and high reflectivity to both heat and light. The aluminum’s strength is made out by chemistry. Pure aluminum is mixed with other elements to create high-strength alloys. Common additives used to increase the strength and formability of aluminum include silicon, magnesium and copper. Aluminum-zinc alloys are some of the strongest alloys available today and are commonly used by the automotive and aerospace industries and are important in other areas of transportation and structural materials. Aluminum can be easily formed and machined, and readily accepts a wide variety of surface finishes, although in most applications it needs no protective coating. Because it is so easy to work with, it can present an affordable alternative to many cheaper but less workable materials.