铌合金电子结构及其高温氧化行为

为了从电子层面揭示Nb合金高温氧化的物理本质,采用递归法计算了Nb合金的电子态密度、原子镶嵌能、亲和能等电子结构参数,探索Nb合金高温氧化机理.研究表明:氧在Nb中具备较高的扩散速率和溶解度,且氧与Nb较易发生反应,生成氧化物,这使Nb的抗高温氧化性较差.原子镶嵌能的计算结果表明,合金元素Ti,Si,Cr在基体中稳定性较低,易向Nb合金表面扩散,形成富Ti,Si,Cr的表层.合金表层中氧与Nb,Ti,Si,Cr间具有较大亲和性,可以生成相应的氧化物,形成对合金具有保护作用的氧化膜.关键词：递归法高温氧化Nb合金

Electronic structure and high-temperature oxidation behavior of Nb alloy

In order to reveal the physical nature of high temperature oxidation of Nb alloy in electron level, the density of states, the atomic embedded energy, the atomic affinity energy and other electronic structure parameters of Nb alloy are calculated by using the recursive method. The high-temperature oxidation mechanism of Nb alloy is investigated. The results show that the diffusion rate and the solid solubility of oxygen are high in the Nb alloy, so oxygen can easily react with Nb to form oxides, which makes the oxidation resistance of Nb alloy poor at high temperatures. The calculated results of atomic embedded energy show that the stabilities of alloying elements (Ti, Si, Cr) are lower in the matrix than in the surface of Nb alloy, so they diffuse easily in to the surface of Nb alloy to form a surface layer enrichment with Ti, Si, Cr. Alloying elements Nb, Ti, Si, Cr have negative affinity energies to oxygen in alloy surface layer, thereby forming the corresponding oxide film, which has a protective effect for Nb alloy.