Inoculation of iron-base alloys

When inoculants such as ferrosilicon and graphite particles are added to iron-base alloys, it has been observed that small carbide particles can be formed in the complex diffusion zone around the dissolving particles. The formation of these carbides depends on whether the solubility product is exceeded as a result of counter-flowing diffusion fluxes of carbide former and carbon. Although the conditions are predicted to favour the homogeneous nucleation of carbides, it is not certain that these act as heterogeneities for the nucleation of graphite since many of them will redissolve. However, an inhomogeneous distribution of carbon will persist for a long time after carbide dissolution. This inhomogeneous distribution will favour the nucleation of graphite during cooling.