1. Meaning

The development of human civilization and the progress of society are closely related to metal materials. After the Stone Age, the Bronze Age and the Iron Age were marked by the application of metal materials. In modern times, a wide variety of metal materials have become an important material basis for the development of human society.

2. Types

Metal materials are usually divided into ferrous metals, non-ferrous metals and special metal materials.

(1) Ferrous metals are also called iron and steel materials, including industrial pure iron containing more than 90% iron, cast iron containing 2% to 4% carbon, carbon steel containing less than 2% carbon, and structural steel, stainless steel, Heat-resistant steel, high-temperature alloy, stainless steel, precision alloy, etc. Black metals in a broad sense also include chromium, manganese and their alloys.

(2) Non-ferrous metals refer to all metals and their alloys except iron, chromium and manganese, which are usually divided into light metals, heavy metals, precious metals, semi-metals, metals and rare earth metals. The strength and hardness of non-ferrous alloys are generally higher than that of pure metals, and the resistance is large and the temperature coefficient of resistance is small.

(3) Special metal materials include structural metal materials and functional metal materials for different purposes. Among them are amorphous metal materials obtained by rapid condensation process, as well as quasicrystal, microcrystalline, nanocrystalline metal materials, etc.; there are also functional alloys such as stealth, anti-hydrogen, superconductivity, shape memory, vibration damping, and metal matrix composites materials, etc.