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 wi...

Recent Developments in Irradiation-Resistant Steels

Perspective of ODS alloys application in nuclear environments

On the role of alloy composition and processing parameters in nanocluster formation and dispersion strengthening in nanostuctured ferritic alloys

High temperature oxidation of fuel cladding candidate materials in steam–hydrogen environments

Creep is a time-dependent mechanism of plastic deformation, which takes place in a range of materials under low stress-that is, under stresses lower than the yield stress. Metals and alloys can be designed to withstand creep at high temperatures, usually by a process called dispersion strengthening, in which fine particles are evenly distributed throughout the matrix. For example, high-temperature creep-resistant ferritic steels achieve optimal creep strength (at 923 K) through the dispersion of yttrium oxide nanoparticles. However, the oxide particles are introduced by complicated mechanical alloying techniques and, as a result, the production of large-scale industrial components is economically unfeasible. Here we report the production of a 9 per cent Cr martensitic steel dispersed with nanometre-scale carbonitride particles using conventional processing techniques. At 923 K, our dispersion-strengthened material exhibits a time-to-rupture that is increased by two orders of magnitude relative to the current strongest creep-resistant steels. This improvement in creep resistance is attributed to a mechanism of boundary pinning by the thermally stable carbonitride precipitates. The material also demonstrates enough fracture toughness. Our results should lead to improved grades of creep-resistant steels and to the economical manufacture of large-scale steel components for high-temperature applications.

M. Inoue

Papers

Alloying design of oxide dispersion strengthened ferritic steel for long life FBRs core materials

Tube manufacturing and mechanical properties of oxide dispersion strengthened ferritic steel