ABSTRACT

We employ first-principles calculations to examine the role of oxidation on the thermal expansion behaviour of a refractory multicomponent alloy. Our results reveal that the linear expansion and the coefficient of volumetric expansion over a range of temperatures have higher values for the oxidised alloy than the pure material. The enhanced expansion for the oxidised alloy is attributed to significant changes in the lattice parameter of the alloy upon surface oxidation. During oxidation, the diffusion of oxygen atoms to the subsurface layer of the alloy after complete surface coverage produces a displacement of the constituent elements that form metal oxides. This depletion creates vacancy sites in the lattice for enabling enhanced expansivity in the oxidised structure relative to the pure refractory alloy.

摘要

我们采用第一性原理计算来检查氧化对难熔多组分合金热膨胀行为的作用。我们的结果表明，在一定温度范围内，线性膨胀和体积膨胀系数比纯金属具有更高的氧化合金值。氧化合金的膨胀性增强归因于表面氧化后合金晶格参数的显着变化。在氧化过程中，完全覆盖表面之后，氧原子扩散到合金的次表面层，导致形成金属氧化物的组成元素发生位移。这种耗尽在晶格中产生空位，从而相对于纯耐火合金能够提高氧化结构的膨胀性。