Alloys The mixture of the elements iron and carbon create what is known as an alloy, and it is much harder and stronger than pure iron. Carbon and many other elements can be combined with iron to form various types of alloys, all of which are referred to as steel.his is known as a face centered cubic (fcc) structure. The ability for an element like iron to exist in more than one structure is one of two fundamental principles in the understanding of steel. The role of carbon Carbon is the principle alloying element that transforms soft iron into hard and useful steel.