Steel. It's a much stronger and much less expensive material.
The most common metal used for standard bicycle frames is steel, although it is possible to get frames made from graphite, aluminum, and titanium alloy.
Most modern bicycle frames are made of one of three components: Aluminum, Steel or Carbon Fiber. Aluminum can make for a more forgiving frame. Steel frames are hardy, transfer power well and are commonly found on BMX bikes and some mountain bikes. Carbon Fiber frames are the lightest and most expensive frames and are only found on the high end road bikes.
They are made of compounds not elements unless they are Iron or Aluminum window frames. Most window frames were made of wood but UPVC is becoming more popular.
Steel Wire in most cases but they can be made of plastic, or aluminum.
The reason they don't make aluminum hammers is because most nails are made of steel and steel nails will destroy the aluminum because steel is a lot harder than aluminum.
Most classic American cars are made out of steel and aluminum. This is because steel and aluminum are sturdy and can withhold a beating and are easy to get dents out of.
Airplanes are made of a variety of materials. The earliest ones were made of pine wood and canvas. Then steel braces and nylon. Airplanes now can be made out of anything from wood and canvas, to magnesium alloys and aluminum. Most private planes are made out of canvas-nylons and steel frames. Commercial jets can be made out of aluminum and new models are starting to use light weight magnesium frames to cut down on weight and improve fuel efficiency. The most common material used now is aluminum and steel alloys.
Most cars have some aluminum in the structure, but for the most part, car bodies are sheet steel. The 1980s DeLorean was constructed from aluminum.
Generally speaking aluminum frames have larger diameter tubes than steel or titanium bikes, but the most obvious is to test with a magnet. If it sticks it's a steel frame. If it doesn't it's probably aluminum. Titanium frames are still so rare that you are very unlikely to buy one w/o knowing.
Steel, aluminum, fiberglass, or carbon fiber depending on the vehicle the hood is installed on. Most are made of steel.
Yes, the can is recyclable in most municipalities because it is made of steel. The lid is made of a steel with an aluminum tab. It is also recyclable in most municipalities, but please check with your local authorities.
Most pistons are cast from aluminium alloys.