Analysis of Structural Condition and Thermodynamics Condition of Graphite Heterogeneity Nucleation in Cast Iron

Based on the empirical electron theory of solid and molecule, the valence electron structures(VESs) of graphite, CaS and MnS in cast iron are calculated, their bond-forming energy F of the structure unit and bond-forming energyEof the crystal plane are defined and calculated. Combined with the nucleation theory of the liquid metal,Fand E are applied to analyze the thermodynamics condition of graphite heterogeneity nucleation in undercooling liquid of case iron, i.e.,GL-FG>GL-FH,>. According to the coincidence lattice model of large-angle grain boundary used commonly in modern times, the corresponding structural condition is analyzed, i.e., the crystal structure of graphite should have the better lattice contract ratio with the crystal structure of its annexed heterogeneous particles.