Solubility of carbon in nanocrystalline a-iron

By using a thermodynamic model of nanocrystalline alloys the grain size effect on the solubility of carbon in a-iron is calculated. More specifically the enrichment at grain boundaries is predicted to result in a solubility enhancement. An experimental setup is devised to measure carbon solubility in nanocrystalline iron powder in equilibrium with graphite. At 390 °C a solubility of 0.514 at% is determined for nanocrystalline iron with a grain size of 23 nm.