Nanocluster formation in oxide-dispersion strengthened steels by internal oxidation subsequent to ultrasonic powder atomization

拟议的项目涉及的基本问题，在处理氧化物弥散强化钢的氧化物纳米团簇如何形成从严重变形的显微组织，随后机械合金化。在这个项目中，我们利用超声波金属粉末雾化为此目的，这使得金属粉末的制备贫金属。在超声金属粉末雾化过程中，原料在电弧熔化器中熔化，电弧熔化器的坩埚连接到超声焊极。超声波发生器的振动导致熔融颗粒的撕裂，并发生快速凝固成具有窄尺寸分布的球形颗粒。电弧熔化和低气流的使用允许实现非常低的间隙含量。这些低于或处于形成氧化物纳米团簇所需的氧含量的数量级，而在机械合金钢中存在巨大的氧过量，这使得难以分析溶解的氧含量和氧化物的沉淀状态。雾化后，纳米团簇通过内氧化形成。在项目过程中，在整个加工链中确定化学成分、微观结构和机械性能。这包括氧化物颗粒尺寸和密度，位错密度和晶粒尺寸的尺度桥接表征技术的评价。这允许在处理步骤期间评估沉淀序列及其对材料的机械行为的影响。

The proposed project deals with the fundamental issue in processing oxide dispersion strengthened steels of how oxide nanoclusters form from the severely deformed microstructure subsequent to mechanical alloying. In this project, we utilize ultrasonic metal powder atomization for this purpose, which allows the preparation of metal powders lean in interstitials. During ultrasonic metal powder atomization, the raw material is melted in an arc melter the crucible of which is attached to an ultrasonic sonotrode. The vibrations of the sonotrode lead to tear off of molten particles and rapid solidification to spherical particles with narrow size distribution occurs. The use of arc melting and low gas flow allows for achieving very low interstitial contents. These are below or in the order of the oxygen contents needed to form oxide nanoclusters whereas in mechanical alloyed steels a tremendous oxygen excess exists which makes the analysis of the solved oxygen content and precipitation state of the oxides difficult. After atomization, the nanoclusters are formed via internal oxidation. During the project, the chemical composition, the microstructure and the mechanical properties are determined throughout the entire processing chain. This includes an evaluation of oxide particle size and density, dislocation density and grain size by scale-bridging characterization techniques. This allows for an assessment of the precipitation sequences during the processing steps and its influence on the mechanical behavior of the materials.