材料期刊网

对钢液中各种固态化合物基底与形核相(δ-Fe和γ-Fe)的价电子结构进行了计算,基于静电作用理论和经验电子理论提出了基底和形核相之间的特征参量△ρ,并对△ρ与钢液非均质形核触媒作用的关系进行了分析和讨论.结果表明:基底和形核相之间的特征参量△ρ越大,非均质形核作用越好.

Solid compounds added into liquid steel can be utilized as substrates for primary ferrite phase or primary austenite phase nucleation during solidification. The effect of solid compounds promoting heterogeneous nucleation can be interpreted as an electrostatic effect between substrates and nucleated phases, with heterogeneous nucleation being considered as caused by the free energy change due to the redistribution of free electrons at the interface of substrate and nucleated phase. In order to evaluate the electrostatic effect, Yu's empirical electron theory was introduced. With concepts of lattice electron and atomic state hybridization brought forward by Yu, the bond length difference method was applied to calculate valence electron structures of substrates and nucleated phases. The electrostatic effect was quantified as a electron transfer rate at the interface of substrate and nucleated phase. Parameter Δρ was proposed to represent the electron transfer rate. In this study, 23 compounds commonly found in liquid steel were selected as the substrates, along with δ-Fe and γ-Fe as the nucleated phases. The valence electron structures of substrates and nucleated phases were calculated on the basis of crystal structure data obtained by experiments. Parameter Δρ between each substrate and δ-Fe/γ-Fe was calculated from the valence electron structures. The results show that, as the parameter Ap increases, the work of heterogeneous nucleation derived from experimental data decreases; the larger Δρ is, the more effective the substrate is for promoting nucleation.