Master alloy is a variety of base alloys for the smelting of steel, cast iron, superalloy, titanium alloy, magnetic alloy, aluminum alloy and non-ferrous metal materials and additives. It cannot be used directly as a metal material. The master alloy is composed of two or more elements, in addition to the mass-produced ferroalloys. Master alloy is designed according to the composition and special requirements of the metal materials. It can be classified into iron base master alloy, nickel masterbase alloy, aluminum base master alloy, etc. according to the matrix composition, or according to the main elements of the alloy, but it is often called special alloy, so as to distinguish it from mass-produced ferroalloy, such as silicon special alloy, calcium special alloy, boron special alloy, chromium special alloy, etc.