pyrophoric alloy

1. A pyrophoric alloy made from a mixture of rare-earth metals.
   稀土金属混合而成的发火合金。
2. A pyrophoric alloy of iron with cerium; used for lighter flints.
   一种含铁和铈的发火合金，用作打火石。

noun

1. an alloy that emits sparks when struck or scratched with steel