EUROPEAN CONGRESS AND EXHIBITION ON ADVANCED MATERIALS AND PROCESSES - EUROMAT 2021

Oxide-dispersion strengthened materials show improved high temperature mechanical properties, their production via mechanical alloying is, however, not only time consuming but also in some cases difficult to implement. Therefore, in order to improve the efficiency of the process of mechanical alloying, cryomilling was investigated for the production of oxide-dispersion strengthened high-entropy-alloys. The prealloyed FeCrMnNiCo powders were milled together with 1 wt.% yttria using a novel cryomilling attritor. The milling was performed at room temperature and at cryogenic temperatures in vacuum under various milling conditions. In order to investigate the effect of cryogenic milling on the microstructure and the yttria dispersions, the milled powders and their cross-sections were analysed using X-ray diffraction and high-resolution scanning electron microscope. The visible yttria dispersion, their morphology and the analysed defect structure of the differently produced powders were compared and the influence of the individual milling parameters with focus on the temperature were investigated. Furthermore, atom-probe-tomography and transmission-electron-microscopy investigations were used for the detection of yttria below the resolution limit of the scanning electron microscope. This represents one further step in understanding of acting mechanisms related to dissolution of second phases during final stages of mechanical alloying.