The document discusses materials used in the automotive and aerospace industries. It notes that the most common materials in automotive are steel, aluminum, magnesium, copper, plastics and carbon fiber. It states that 39 types of plastics are used in cars, with the top four polymers making up 70% of plastic. Common aerospace materials include aluminum alloys, titanium alloys, high-strength steels, and composites, accounting for over 90% of airframe weight. In defense, ceramics are mainly used as armor and alloy steels are most common for tank armor.