Oxide dispersion strengthened and oxidation resistant vanadium alloys

钒基合金是开发新型高温材料的有希望的候选材料，这是由于它们的高比机械强度。这可以通过与引起沉淀硬化的元素（例如Si和B）或与氧化物颗粒（所谓的ODS颗粒（氧化物弥散体））合金化来实现。然而，最佳的机械性能需要在材料的微观结构中的V固溶体基质。这种基质在氧化环境中又极其脆弱。原因是V2 O 5的形成-与纯金属（Ts（VanO 2）= 1919 °C）相反-在高于约1000 ° C的温度下是液体。690°C。这种氧化行为是钒基合金至今尚未被考虑用于高温应用的原因。更糟糕的是，钒酸盐很容易在不同的氧化态之间变化，这极大地加速了镍基、钴基或铁基材料的高温腐蚀，特别是当它以熔融形式存在时。为了使钒合金能够在高温下使用，提出了一种全新的氧化保护方法，同时进行氧化物颗粒强化：使用含Mg和Ca的氧化物颗粒生产抗氧化的ODS-V-Si合金。如果采用足够数量的耗氧物质颗粒，预计可防止在高温下形成液相。同时，我们期望颗粒的强化效果，这在从环境温度到1100°C的这种合金的潜在应用范围内是量化的。该项目的目的是澄清（1）在钒材料中可以形成MgO、CaO或正硅酸镁颗粒均匀微观结构的体积分数，（2）MgO的浓度，需要CaO或正硅酸镁来防止液相形成或触发自保护机制，（3）通过添加氧化物分散体可以实现多大的强化效果以及ODS颗粒如何影响钒合金的蠕变行为。计划进行相关调查，以便系统地分析粉末和合金系统的组成和微观结构，以及随后的氧化行为。主要的焦点在于确定ODS颗粒和钒固溶体之间的最佳比例，与抗氧化性和机械性能的关系。因此，采取了一种全新的合金设计方法，以便同时提高抗氧化性和机械性能。

Vanadium-base alloys are promising candidates for the development of novel high temperature materials due to, among others, their highly specific mechanical strength. This can be achieved by alloying with elements that cause precipitation hardening (such as Si and B) or with oxide particles, so-called ODS particles (oxide dispersoids). However, optimal mechanical properties require a V solid solution matrix in the materials microstructure. This matrix in turn is extremely vulnerable in oxidising environments. The reason is that the formation of V2O5, which – in contrast to the pure metal (Ts (Vanadium) = 1919 °C) – is liquid at temperatures above ca. 690°C. This oxidation behaviour is the reason why vanadium-base alloys have not been considered for high temperature application until now. To make matters worse, vanadate changes very easily between different oxidation states, which extremely accelerates the high temperature corrosion of Ni-, Co- or Fe-base materials, especially if it is present in a molten form. This also excludes an application of currently available vanadium alloys in combination with these materials.In order to make vanadium alloys applicable at high temperatures, a completely new approach of oxidation protection is proposed with simultaneous oxide particle strengthening: Using Mg- and Ca-containing oxide particles to produce oxidation-resistant ODS-V-Si alloys. Introduced in sufficient amounts, the ODS particles are expected to prevent the formation of liquid phase at high temperatures. At the same time we expect a strengthening effect of the particles, which is to be quantified in the potential application range of such alloys from ambient temperature to 1100°C.The purpose of the project is to clarify (1) up to which volume fraction of MgO, CaO or magnesium orthosilicate particles homogeneous microstructures can be formed in vanadium materials, (2) which concentration of MgO, CaO or magnesium orthosilicate is required to prevent liquid phase formation or to trigger a self-protecting mechanism, (3) how much of a strengthening effect can be achieved by adding oxide dispersoids and how the ODS particles affect the creep behaviour of vanadium alloys. Accompanying investigations are planned in order to systematically characterise the powder and alloy systems in terms of their composition and their microstructure and, subsequently, their oxidation behaviour. The main focus lies on determining the optimal ratio between ODS particles and vanadium solid solution in relation to oxidation resistance and mechanical properties. Thus, a completely new approach of alloy design is taken in order to improve oxidation resistance and mechanical properties at the same time.