Günay, GökhanZienert, TiloEndler, DirkAneziris, Christos G.Biermann, HorstWeidner, Anja2026-09-232026-09-232026-09-23https://opara.zih.tu-dresden.de/handle/123456789/2936The present study explores the properties of both fine- and coarse-grained refractory composites made from niobium and alumina, designed for high performance applications at extreme temperatures, in abrasive environments, and under mechanical stresses. The effects of various production methods, including casting and extrusion, and different alumina particle sizes (fine or coarse) on the mechanical properties under compressive loads are investigated. Compression tests, as well as stress-relaxation and creep tests under compressive loads, are conducted at room temperature and high temperatures up to 1500 °C. The results are analysed concerning initial open porosities and particle sizes. The findings reveal that both particle size and manufacturing method significantly affect the mechanical properties of Nb-Al2O3 refractory composites. Additionally, the choice of production technique substantially influences the microstructure of the composites, leading to noticeable differences in mechanical performance. This research highlights the essential role of optimizing particle size and production methodologies to enhance the operational properties of Nb-Al2O3 refractory composites.4::43