The history of human civilization is, in a sense, a history ofmaterials evolution. From the Stone Age to the Bronze Age and then the Iron Age, metallic materials have always been the physical backbone supporting social development. However, the widespread use of a metal depends not only on its abundance in the Earth's crust but also onthe difficulty of its smelting technology, along with its physical properties and socio-economic costs.

The Logic of Material Selection

In engineering practice, we follow the principle that "properties determine use", but "properties" is not the only criterion. When deciding whether a material should be adopted on a large scale, a multi-dimensional evaluation model must be established:

• Physical/Chemical Properties:e.g., electrical conductivity, hardness, corrosion resistance (the dense oxide film on aluminum is key to its corrosion resistance).
• Resources & Technology:Abundance in the Earth's crust and the energy required to extract the metal (e.g., the electrolytic process for aluminum).
• Economic Cost:Raw material price and processing costs (e.g., silver is conductive but expensive).
• Environmental Impact:Ease of recycling and the overall environmental burden.