As we all know, metals exist in nature in compound forms, known as compounds.
Only those extremely inactive metals exist as elements, such as gold, silver, platinum, palladium... These precious metals are stable in nature and rarely react with other substances, therefore they are also known as inert metals.
Hence, most of the metals that humans can obtain in nature exist as mineral compounds, which require smelting to obtain new metal elements.
However, pure metal elements have singular physical properties and often do not meet usage requirements.
For instance, it is widely known that pure iron is actually very soft, and only when it forms an iron-carbon alloy with carbon does it have a hard texture.
Moreover, depending on the temperature, the lattice arrangement within iron crystals varies. Based on this physical property, iron-carbon alloys can be processed at different temperatures to obtain iron-carbon alloys with differing properties, commonly known as steel.
