zh-hans:碳化三铁 zh-hans:铁素体 zh-hans:奥氏体

珠光体，或称波来铁（英语：Pearlite），是钢铁的一种由铁素体和雪明碳铁构成的层状组织。波来铁中通常含有88%的肥粒铁和12%的雪明碳铁，整体的含碳量约为0.8%。波来铁组织在钢的显微组织中是最常见的。

波来铁的生成，是由含碳量约0.8%的沃斯田铁，在极慢速的冷却中，冷却到摄氏723度时开始产生相变化，而同时析出肥粒铁和雪明碳铁，成为波来铁组织，由于是由单相的固体同时析出两种相，因此这种变态反应称为共析反应或共析变态，而含碳量0.8%的钢，就称为共析钢。若是含碳量较低的情况，会在较高温时先开始析出肥粒铁，而使剩余未发生变态的沃斯田铁含碳量逐渐提高，到了共析点时开始生成波来铁，这种含碳量低于波来铁的钢，就称为亚共析钢。而若含碳量较高，则会先析出雪明碳铁，使沃斯田铁的含碳量逐渐降低，到了共析点时开始生成波来铁，这种钢就称为过共析钢。

Pearlite is a two-phased, lamellar (or layered) structure composed of alternating layers of ferrite (88 wt%) and cementite (12 wt%) that occurs in some steels and cast irons. In fact, the lamellar appearance is misleading since the individual lamellae within a colony are connected in three dimensions; a single colony is therefore an interpenetrating bicrystal of ferrite and cementite. In an iron-carbon alloy, during slow cooling pearlite forms by a eutectoid reaction as austenite cools below 727 °C (1,341 °F) (the eutectoid temperature). Pearlite is a microstructure occurring in many common grades of steels.