Superior radiation-resistant nanoengineered austenitic 304L stainless steel for applications in extreme radiation environments

Abstract

Nuclear energy provides more than 10% of electrical power internationally, and the increasing engagement of nuclear energy is essential to meet the rapid worldwide increase in energy demand. A paramount challenge in the development of advanced nuclear reactors is the discovery of advanced structural materials that can endure extreme environments, such as severe neutron irradiation damage at high temperatures. It has been known for decades that high dose radiation can introduce significant void swelling accompanied by precipitation in austenitic stainless steel (SS). Here we report, however, that through nanoengineering, ultra-fine grained (UFG) 304L SS with an average grain size of ~100 nm, can withstand Fe ion irradiation at 500°C to 80 displacements-per-atom (dpa) with moderate grain coarsening. Compared to coarse grained (CG) counterparts, swelling resistance of UFG SS is improved by nearly an order of magnitude and swelling rate is reduced by a factor of 5. M23C6 precipitates, abundant in irradiated CG SS, are largely absent in UFG SS. This study provides a nanoengineering approach to design and discover radiation tolerant metallic materials for applications in extreme radiation environments.

Enhancing radiation tolerance by controlling defect mobility and migration pathways in multicomponent single-phase alloys

“…Introducing high-densities of defect sinks, such as secondary phase or grain boundaries, is a popular way for reducing residual defects in irradiated materials. The success of this approach has been demonstrated in oxide-dispersion-strengthened steels567, nano-layered8 and nano-grained polycrystalline alloys9. However, the nanostructures in the above materials are often unstable at elevated temperatures and in extreme radiation environments1011.…”

Dispersion of carbon nanotubes in aluminum improves radiation resistance

“…3,4 Nanostructuring is a key strategy to improve the radiation resistance of materials. [5][6][7][8] Carbon nanotubes (CNTs) are well known to be a strong and flexible nanomaterial. If CNTs are uniformly dispersed inside metal as 1D fillers [9][10][11] , its high aspect ratio  (up to 10 8 ) 12 should create prolific internal interfaces with the metal matrix that may act as venues for the radiation defects to recombine (self-heal).…”

“…This is still an order of magnitude longer than the typical size of a radiation cascade, which is 10-20 nm, therefore the improvement in porosity suggests that porosity development involves length scales quite beyond a single cascade annealing. For comparison, ultra-fine grained austenitic stainless steel with a grain size of 100 nm was recently shown to exhibit 5 times slower void swelling rate up to 80 DPA,7 and L furthest in that case should be around 50 nm if all the grain boundaries (GB) are effective venues for recombination. Compared to that system of "2D nanoengineered" network of GBs7 , our "1D nanoengineered" CNTs/Al has 4 times longer L furthest and 15 times less interfacial area per volume.…”

Microstructural Evolution of High-Strain-Rate Severe Plastic Deformation Processed 316L during Kr Ion Irradiation and elevated Temperature Exposures

“…Enhanced irradiation damage tolerance has been reported for materials with microstructures comprising high densities of sink sites for annihilation of excess point defects, e.g. intra-granularly provided by thermodynamically stable precipitates and inter-granularly as grain boundaries [3][4][5][6][7].…”

“…Enhanced irradiation damage tolerance has been reported for materials with microstructures comprising high densities of sink sites for annihilation of excess point defects, e.g. intra-granularly provided by thermodynamically stable precipitates and inter-granularly as grain boundaries [3][4][5][6][7].Here we report a transmission electron microscopy (TEM) based investigation of the microstructural development of 316L SS alloys modified by novel high-strain rate severe plastic deformation (SPD) methods based on linear plain strain processing under exposures to Kr ion-irradiation and elevated temperatures [8][9][10][11]. The SPD-modified SS offer significantly improved mechanical strength, fatigue performance, resist thermal coarsening up to ~650˚C, and exhibit highly deformed, ultra-fine-grain to nano-scale refined grains of austenitic-Fe with lath-like morphology and trace amounts of martensite [8][9][10][11] (Fig.…”