Titanium (element)
鐟 is a rare kanji that specifically names the metallic element titanium. Its meaning is narrow and technical, with no common abstract extensions.
鐟 is a modern coined character for titanium, combining the metal radical 金 with 替, which likely contributes the sound テイ. It does not have a long historical development.
The metal radical 金 on the left marks it as a metal, and the right side 替 suggests replacement. Think of titanium as the replacement metal for stronger, lighter alloys.
For テイ, imagine a titanium tea kettle: tea -> テイ, and the kettle is made of this strong, light metal.