Recent Developments in Irradiation-Resistant Steels

Abstract

Advanced fission and future fusion energy will require new high-performance structural alloys with outstanding properties that are sustained under long-term service in ultrasevere environments, including neutron damage producing up to 200 atomic displacements per atom and, for fusion, 2000 appm of He. Following a brief description of irradiation damage and damage resistance, we focus on an emerging class of nanostructured ferritic alloys (NFAs) that show promise for meeting these challenges. NFAs contain an ultrahigh density of Y-Ti-O-enriched dispersion-strengthening nanofeatures (NFs) that, along with fine grains and high dislocation densities, provide remarkably high tensile, creep, and fatigue strength. The NFs are stable under irradiation up to 800°C and trap He in fine-scale bubbles, suppressing void swelling and fast fracture embrittlement at lower temperatures and creep rupture embrittlement at high temperatures. The current state of the development and understanding of NFAs is described, along with some significant outstanding challenges.

Development of a Novel Melt Spinning-Based Processing Route for Oxide Dispersion-Strengthened Steels

“…[1][2][3][4][5] The widely practiced processing route for these ODS steels is essentially a two-step powder metallurgy process, consisting of mechanical alloying (MA) of 10-to 90-lm-diameter pre-alloyed Fe-based alloy powder together with a normally nano-sized (20 to 50 nm) Y 2 O 3 powder until fine-scale mixing/alloying is achieved, followed by consolidation of the powder into a bulk form typically by hot isostatic pressing (HIP) or related technique. [5][6][7][8][9][10] This MA approach is now well optimized and convenient for laboratory-based studies, providing good quality material sufficient for detailed microscopy, irradiation, and mechanical property assessment. However, in technological terms, disadvantages of the MA route include prolonged processing time, small batch size, tendency for contamination associated with the high specific area of the powder, and the high inherent cost of the pre-alloyed feedstock powders, which combine to restrict wider commercial implementation of the MA-based route.…”

Evaluation of Mechanical Properties of Σ5(210)/[001] Tilt Grain Boundary with Self-Interstitial Atoms by Molecular Dynamics Simulation

“…These defects and flaws not only deteriorate the physical properties of materials but also cause direct structural failure [7]. Compared with the conventional polycrystalline materials, nanocrystalline materials exhibit the superior property of radiation resistance due to the significantly decreased grain size and the increased volume fraction of grain boundary (GB) [1,2,8,9]. It has been demonstrated that grain boundary can act as an efficient sink for reducing the accumulation of radiation defects in nanocrystalline metals [10][11][12][13], alloys [14,15], and oxides [16,17].…”

Tensile and fracture characteristics of oxide dispersion strengthened Fe–12Cr produced by hot isostatic pressing

“…Oxide nanoparticles also provide a high density of sinks for irradiation induced point defects and He. This would reduce irradiation hardening and restrain the formation of He bubbles at grain boundaries, preventing embrittlement [6,7].…”