Cast and White Irons
Cast irons are used for many applications. The reliabiity of cast iron depends on the microstructure of the graphite in the material. If the graphite forms flakes, then the cast iron will be brittle, becoming more so over time. Cast iron with the addition of either magnesium or cerium, results in the graphite forming nodules. Nodular cast iron has much better ductility than gray cast iron.
Cast Irons are difficult materials to prepare properly because the graphite nodules or the graphite flakes are easily fractured and pulled out during preparation. By minimizing the sectioning damage and starting with a modest grit size SiC paper, retaining these difficult particles can be accomplished.