Crystallography of Pearlite

The cl)'stallogral)hy oj I)eorlite has been investigated lIlaini;' by means oj transmission electron microscolY. The I)earlite was obloined by the isothermal decomposition oj 0 high purity elliectoid iron- carbon allstenite. The results showed that the Lamellar l)Carlite exhibited both the S agar )'atskii (passiM), the Isoichev) and the second Petch jerrite/cementite rela tionships with the (IOl),.//f 1l21" and the (OOl),./Ii 125:" habit 1)lanes resllectively. Soth habits can be explained in terms oj a low suface energ)' inte~race betweenjerrite and cementite. Decreasing the transjormation temperalure produced the degenerate I)earlite where the cementite lamellae were broken Ul) intofine IJlates. Oc casionally an altemative struclure consisted of the rows oj cemenlile Iwrticles I)orallel to the jerrite/austenite inte~Iace in a similar jashion to the inter I)hase precil)itation oj alloy carbides was observed to jorm.