ODS-materials for high temperature applications in advanced nuclear systems. (December 2016)

• Record Type: Journal Article
• Authors: Eiselt, C.C.; Schendzielorz, H.; Seubert, A.; Hary, B.; de Carlan, Y.; Diano, P.; Perrin, B.; Cedat, D.
• Is Part Of: Nuclear materials and energy. Volume 9(2016)
• Page Start: 22
• Page End: 28
• Publication Date: 2016-12
• Subjects: Ferritic ODS alloy -- Powder metallurgy -- Hot extrusion -- EBSD -- SANS -- Fracture toughness; Nuclear energy -- Periodicals; Nuclear fuels -- Periodicals; Nuclear reactors -- Materials -- Periodicals; Radioactive substances -- Periodicals; 621.4833
• DOI: 10.1016/j.nme.2016.08.017
• Languages: English
• ISSNs: 2352-1791

Abstract

Highlights: Successful upscaled powder metallurgical ODS production via hot extrusion and HIP. Bi-modal distribution of ODS particle sizes with precipitates of 3 nm and of 9–10 nm. Strong 〈110〉 texture corresponding to the fiber α as after hot extrusion. Increased (fracture) toughness in the L-R orientation perpendicular to the extrusion direction. Application of SST test technique for fracture toughness tests by use of 0.2T C(T)s. Abstract: A ferritic ODS-alloy (Fe-14Cr-1W-0.25Ti) has been manufactured by application of the powder metallurgical production route involving at first mechanical alloying of ∼10 kg pre-alloyed steel powder together with an Y2 O3 addition for 12 h in a high energy industrial ball mill under hydrogen atmosphere at the company ZOZ GmbH. As a next step, one part of the alloyed powder was hot extruded into rods while another portion was hot isostatically pressed into plates. Both materials were then heat treated. A characterization program on these ODS-alloy production forms included microstructural and mechanical investigations: SANS and TEM assume the existence of Y2 Ti2 O7 nano clusters and show a bimodal distribution of ODS-particle sizes in both ODS variants. EBSD maps showed a strong 〈110〉 texture corresponding to the α fiber for the hot extruded ODS and a slight 〈001〉 texture for the hipped ODS material. Fracture toughness tests in different specimen orientations (extruded ODS) with mini 0.2T C(T) specimens together with Charpy impact tests revealed anisotropic mechanical properties: Promising (fracture) toughness levels were obtained in the specimen orientation perpendicular to the extrusion direction, while the toughness levels remained low in extrusion direction and generally for the hipped ODS material at all test temperatures. The fracture toughness tests were performed according to ASTM E 1921 and 1820 standards.