Its Use in Alloys
There are hundreds of alloys that contain carbon. The most common of these alloys is steel, sometimes called "carbon steel" (see Category:Steels). All kinds of steel contain some amount of carbon, by definition, and all ferrous alloys contain some carbon.
Some other common alloys that are based on iron and carbon include anthracite iron, cast iron, pig iron, and wrought iron.
In more technical uses, there are also spiegeleisen, an alloy of iron, manganese, and carbon; and stellite, an alloy of cobalt, chromium, tungsten, and carbon.
Whether it was placed there deliberately or not, some traces of carbon is also found in these common metals and their alloys: aluminum, chromium, columbium, magnesium, molybdenum, niobium, thorium, titanium, tungsten, uranium, vanadium, zinc, and zirconium. For example, many of these metals are smelted with coke, a form of carbon; and aluminum and magnesium are made in electrolytic cells with carbon electrodes. Some distribution of carbon into all of these metals is inevitable.
Read more about this topic: Compounds Of Carbon