合金渗碳体稳定性研究

依据固体与分子经验电子理论，建立“实际晶胞模型”，采用统计法计算合金元素M（Cr、V、W、Mo、Mn）取代渗碳体（θ-Fe₃C）不同位置和数目的Fe¹、Fe²后的价电子结构.定义稳定性因子P并讨论分析不同位置、数目和类型的Fe原子被M取代后，P的变化规律.结果表明：晶格电子密度、原子键对称性和键能，对稳定性有重要影响；M取代Fe²比取代Fe¹稳定，Cr、Mo、W、V成对取代2、3或6、7位置的2个Fe²最稳定；合金渗碳体的稳定性按W、Cr、V、Mo、Mn的顺序递减.

A Study on Stability of Alloyed Cementite

With empirical electronic theory of solids and molecules (EET), actual model for unit cell of cementite was built. A statistical method was applied to compute valence electron structure (VES) of cementite of θ-Fe₃C with specified number of Fe atoms substituted by alloyed atom of M(Cr, V, W, Mo, Mn). By definition stability factor, stability of alloyed cementite with different type, number and site of Fe atoms substituted were calculated and analysized. It shows that density of lattice electron, symmetry of bonds and bond energy have great influence on stability of alloyed cementite. It is more stable as M substitutes for Fe² than Fe¹. Alloyed cementite is the most stable as Cr, Mo, W and V substitutes for 2 atoms of Fe² at sites of No.2 and 3 or No.6 and 7. Stability of alloyed cementite decreases in order of W, Cr, V, Mo and Mn.