noun
ferroalloy
Technical term for an alloy of iron with one or more other elements, used in steelmaking.
製鋼工程では、合金鉄を添加して鋼の特性を調整する。
In the steelmaking process, ferroalloys are added to adjust the properties of the steel.
合金 is a general term for any alloy, while 合金鉄 specifically refers to iron-based alloys used in steel production.
Compound of 合金 (alloy) and 鉄 (iron). The term is a direct calque of English 'ferroalloy'.