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[Display omitted] • A dual-function and pH-universal electrocatalyst of CoRu/C was synthesized. • The CoRu/C exhibits excellent electrocatalytic activity for overall water splitting. • The crystal defects could account for the enhanced electrocatalytic performance. Exploring highly-efficient and pH-universal overall water splitting electrocatalysts are critical but keep challenging. Herein, a highly-efficient, dual-function and pH-universal electrocatalyst consisting of CoRu alloy nanoparticles embedded in the carbon matrix (CoRu/C) was successfully synthesized through an acid etching-pyrolysis conversion process using ZIF-67 as a precursor. Benefiting from the rich crystal defects created during the alloy formation process that could serve as active catalytic sites and the optimized electronic structure, the as-obtained CoRu/C electrocatalyst required overpotentials of only 18 and 37 mV to reach a current density of 10 mA cm−2 for hydrogen evolution reaction (HER) and 184 and 170 mV for oxygen evolution reaction (OER) in 1.0 M KOH and 0.5 M H 2 SO 4 aqueous solution, respectively. For practical application, the CoRu/C catalyst only needs a cell voltage of 1.49 and 1.45 V in a two-electrode overall water splitting system to achieve a current density of 10 mA cm−2 in alkaline and acidic medium, respectively. The present work paves a new way for the design and construction of efficient bifunctional electrocatalyst for overall water splitting, and would inspire widespread research interest in the field of energy storage and conversion. [ABSTRACT FROM AUTHOR]

• Two CCAs demonstrated reduced void swelling compared to less complex materials. • Increasing temperature from 500 to 600 °C slightly reduced swelling levels in CCAs. • Swelling levels increased significantly with temperature in pure Ni and Fe 56 Ni 44. • Measured stacking-fault energy (SFE) increased with Mn-content between CCAs. • Increased swelling corresponded to lower faulted loop sink strength, higher SFE. This work attempts to link the microstructural evolution of single-phase compositionally complex alloy (CCA) compositions under dual-beam irradiation to their Mn-content via the stacking-fault energy (SFE) and vacancy migration energies. Two alloys, Cr 18 Fe 27 Mn 27 Ni 28 and Cr 15 Fe 35 Mn 15 Ni 35 , along with less compositionally complex pure Ni and Fe 56 Ni 44 binary were irradiated at 500 and 600 °C under dual-beam 1 MeV Kr2+ and 16 keV He+ heavy-ions up to 7 displacements per atom (dpa) with a He/dpa ratio of 0.75 %/dpa using in situ transmission electron microscopy (TEM). Due to the bubble-stabilizing effect of implanted He, bubbles were observed in all irradiations, and populations of faulted interstitial loops were characterized in Cr 18 Fe 27 Mn 27 Ni 28 and Cr 15 Fe 35 Mn 15 Ni 35. A reduction in swelling was observed in the two CCAs compared to pure Ni and Fe 56 Ni 44. Although swelling increased from 500 to 600 °C in Fe 56 Ni 44 , Cr 15 Fe 35 Mn 15 Ni 35 and Cr 18 Fe 27 Mn 27 Ni 28 both swelled slightly more at 500 °C. This was attributed to the difference in vacancy mobility, stronger pinning effect of vacancies on He, and the sink strength of faulted dislocation loops. Faulted interstitial loops nucleated with a higher number density and dislocation line density in Cr 15 Fe 35 Mn 15 Ni 35 at both temperatures, and at 600 °C in both materials. The differences in faulted loop population and temperature effect on swelling are correlated to the Mn-content and the measured SFE (20.2 ± 6.7 mJ/m2 for Cr 18 Fe 27 Mn 27 Ni 28 and 9.2 ± 3.4 mJ/m2 for Cr 15 Fe 35 Mn 15 Ni 35). [Display omitted] [ABSTRACT FROM AUTHOR]

A 150 μm thick fully dense Ni coating was deposited on AZ31B magnesium alloy by a newly developed in-situ shot-peening-assisted cold spray process. Strong adhesion strength of Ni coating (>65.4 MPa) was achieved. The present Ni coated AZ31B reveals comparable electrochemical behavior with annealed bulk Ni in 3.5 wt.% NaCl aqueous solution. Long-term immersion test (1000 h) and NaCl salt spray test (1000 h) further verified the robust corrosion resistance of the cold sprayed Ni coating. This work provides a novel green approach for corrosion protection of magnesium alloys. [ABSTRACT FROM AUTHOR]

Helium bubble formation was examined by scanning/transmission electron microscopy (S/TEM) in Fe-9/10Cr binary alloys and two dispersion strengthened nanostructured alloys (CNA3 and 14YWT containing 5–10 nm diameter carbide and oxide particles, respectively) after ex-situ and in-situ He implantation to ~10,000 appm at 500 to 900 °C. The combination of high-resolution STEM images and electron energy loss spectroscopy (EELS) revealed that the Y-Ti-O nanoparticles in 14YWT were uniformly distributed and exhibited a one-to-one relationship for bubble attachment to the nanoclusters. In the in-situ experiment at 900 °C, grain boundary cracking was severe in the Fe-10Cr model alloy, but not in the nanostructured alloys. From 500 to 900 °C, the bubble size generally increased with increasing irradiation temperature, while the bubble density decreased with increasing temperature. At the same temperatures, the bubble size in the implanted materials was in the order of Fe-9/10Cr > CNA3 > 14YWT, while the bubble density showed the opposite order. The observed bubble number densities for the nanostructured alloys are comparable to the nanoparticle density, suggesting that the nanoparticles in both alloys were effective in trapping He. Our results indicate that very high He concentrations can be managed in nanostructured alloys by sequestering the helium into smaller bubbles (which leads to a lower volume swelling value) and to shield He from the grain boundaries. This can be attributed to the much higher sink strength associated with the nanoclusters or the He trapping ability between different types of nanoclusters. [Display omitted] [ABSTRACT FROM AUTHOR]

• Three Ni powders were sprayed on AZ31B by cold spray for corrosion protection. • Coating microstructures and corrosion performances were correlated with powder feature. • Powder surface protruding granules will hinder inter-particle intimate contact. • The gas-atomized smooth Ni powder can give > 3000 h corrosion protection for AZ31B. Three nickel (Ni) powders, i.e. gas-atomized spherical Ni (GA-Ni), carbonyl irregular Ni (C-Ni), and electrolytic dendritic porous Ni (E-Ni), were sprayed on magnesium alloys by an in-situ micro-forging assisted cold spray method. Although all deposited coatings present extremely low porosity, the C-Ni and E-Ni coatings reveal poorer inter-particle bonding than GA-Ni coating. Electrochemical tests reveal that the inter-particle gaps will act as fast pathways for the corrosive media to penetrate the coatings, thereby the GA-Ni coating with intimate inter-particle boundaries can isolate the corrosive media for 3000 h and the C-Ni and E-Ni coatings fail after <10 h corrosion. [ABSTRACT FROM AUTHOR]

The attractive mechanical properties and superior resistance to void-swelling make ferritic/martensitic alloys a promising structural material for advanced nuclear reactors. However, one anomaly that has intrigued researchers for more than 50 years is the proportion of two types of dislocation loops in Fe and Fe-Cr alloys with Burger vectors b =½<111> and b =<100>. Although the possible mechanisms responsible for the presence of 〈100〉 loops continue to be the subject of intense modeling studies, there remains incomplete experimental understanding of fundamental irradiation processes in Fe(Cr) alloys. Here, the dose dependence of the irradiation-induced microstructural evolution was examined from 0 to 20 displacement per atom (dpa) in high purity Fe and Fe-10Cr during simultaneous dual-beam (1 MeV Kr + 10 appm He/dpa) irradiation at 435 °C. We experimentally revealed that the mechanism for the formation of 〈100〉 loops may not follow the conventional simple dislocation reaction between two ½<111> loops. Real-time dynamic formation and evolution of defects including black dot loops, loop coarsening, loop decoration, network dislocations, and cavities were demonstrated. Several results indicated that the addition of Cr and He could impede dislocation loop motion. The evolution of the defect size/density and relative fraction of ½<111> vs 〈100〉 loops were quantitatively summarized. With increasing dose, ½<111> loops became the dominant type of loop in both materials. Notably, 〈100〉 loops were predominantly observed near grain boundaries only for pure Fe, while arrays of nanoscale black dot defects composing the 〈100〉 loop strings were observed in plenty in Fe-10Cr. [Display omitted] [ABSTRACT FROM AUTHOR]

To evaluate the potential of high entropy alloys (HEAs) for nuclear applications, two HEAs, Al 0.3 CoCrFeNi and CoCrFeMnNi, and a conventional Type 316H stainless steel (SS) were irradiated with 1 MeV krypton ions at 500 °C up to 1 dpa, and examined in-situ with a transmission electron microscope (TEM). After irradiation, a high density of ordered L1 2 nanoparticles was observed in Al 0.3 CoCrFeNi. In contrast, no phase transformation was observed in CoCrFeMnNi and 316H SS. In the thin foil regions of TEM samples, stacking-fault tetrahedra were observed in the HEAs. In the thick foil regions, interstitial dislocation loops were observed for all alloys, and the areal loop density increased linearly with foil thickness. The Al 0.3 CoCrFeNi had the largest loop size (the lowest density), followed by the CoCrFeMnNi and then the 316H SS. The higher loop nucleation rate in the 316H SS was attributed to carbon content. The degree of irradiation hardening was slightly lower for the HEAs than for the 316H SS, which is a promising sign for the nuclear application of HEAs at high temperatures. Bright-field TEM micrographs of Al0.3CoCrFeNi, CoCrFeMnNi and 316H SS irradiated with 1 MeV Kr ions at 500 °C to 1 dpa. All images were taken at similar foil thickness near 110 zone axis with g = 200. The two high entropy alloys exhibited significantly larger size and smaller density of dislocation loops as compared with the 316H stainless steels. Image 1 [ABSTRACT FROM AUTHOR]

Strain glasses (STGs), which are characterized by nanodomains of martensite formed via a strain glass transition, can produce many unusual properties not possessed by normal martensitic alloys. These nanodomains originate from the formation of short-range strain ordering by the disruption of otherwise long-range strain ordering or normal martensitic transformation through sufficient atomic/nanoscale random stress/strain field. So far the atomic/nanoscale randomness is known to be from either point defects, dislocations, or nanoprecipitates. Here we report a spinodal STG alloy Mn 60 Cu 40 , which stems from nanoscale composition modulations (5-20 nm) formed in the early stage of spinodal decomposition, which is identified by STEM-EDS and HRTEM. For short-time (<50 min) aged sample, a strain glass transition was identified by its typical signatures including invariance of global face-centered cubic (fcc) structure with cooling, frequency dependence of elastic moduli at STG transition temperature (T g) following a Vogel-Fulcher relationship, non-ergodicity as manifested by zero-field-colling/field-cooling curves, and the formation of martensitic face-centered tetragonal (fct) nanodomains. For long-time (≥50 min) aged sample, a normal martensitic transition from fcc to fct appears with cooling, being consistent with literatures. As the result, a temperature vs. aging-time phase diagram of spinodal STG was established and shows a crossover from STG to martensite above a critical aging time. The spinodal STG exhibits a non-magnetic Elinvar behavior, i.e., nearly constant elastic modulus over a wide temperature range, together with high-damping capacity. We anticipate that the spinodal STG and associated novel properties may also be found in other metallic and ceramic spinodal materials. [Display omitted] [ABSTRACT FROM AUTHOR]

FeCrAl alloy is one of the promising cladding materials in the advanced nuclear reactors. Here we compare the irradiation response of the nanolaminate (NL) and coarse-grained (CG) FeCrAl alloys, by performing He ion irradiation followed by in situ Kr ion irradiation in a transmission electron microscope at 450 °C. NL alloy has reduced He bubble induced swelling and decreased the density of dislocation loops in comparison to the CG alloy. The distribution of He bubbles appears to be dependent on misorientation angles of high angle grain boundaries. A new type of nanoprecipitates was identified in the irradiated CG FeCrAl without noticeable chemical segregation. Chemical segregation occurred along the laminate boundaries in the irradiated NL FeCrAl alloy. [Display omitted] [ABSTRACT FROM AUTHOR]

The effect of samarium (Sm) addition on the microstructure, mechanical performance and corrosion behavior of extruded AZ41- x Sm (x = 0%, 1%, 2% and 3%) alloys has been investigated by using optical microscope (OM), X-ray diffusion (XRD), scanning electronic microscope (SEM) equipped with energy dispersive spectroscope (EDS), tensile testing, hydrogen evolved and electrochemical tests. It is observed that Sm alloyed AZ41 alloys consist of α -Mg substrate, β -Mg 17 Al 12 and Al 2 Sm intermetallic. The β -phase is gradually inhibited with increasing Sm content. The tensile testing result shows that the appropriate amount of Sm addition slightly enhances the mechanical strength. 2Sm alloyed alloy (AZ41-2Sm) displays optimal tensile properties, with a yield tensile strength (YTS) of 216.4 MPa, ultimate tensile strength (UTS) of 295.9 MPa and elongation (EL) of 15.9%, which is the result of second phase strengthening. The addition of Sm significantly improved the corrosion resistance of AZ41 alloy. The AZ41-1Sm alloy exhibits the best corrosion resistance properties with a corrosion rate about one-half that of the AZ41 alloy based on the hydrogen evolved and electrochemical test. • Al 2 Sm is formed in the as-extruded AZ41 alloy with Sm addition. • The AZ41 alloy is coarsened by the addition of 1–2% Sm, but refined by 3% Sm. • The mechanical properties of AZ41 alloy are enhanced slightly by the addition of Sm. • The AZ41-1Sm alloy shows the optimal corrosion resistance of the AZ41-xSm alloys. [ABSTRACT FROM AUTHOR]

Refractory alloys consisting of reduced activity elements are attractive for nuclear applications to allow safe post-service recycling and meet fusion reactor requirements. Here, ion irradiation response was studied for a newly developed refractory high entropy alloy, HfTaTiVZr, with low activation constituent elements. Ion irradiation led to around 20% hardening for the high entropy alloy compared to 50% hardening for stainless steel under identical conditions. Superior irradiation resistance of the concentrated alloy was explained by the reduced mobility of point defects and self-healing ability. [ABSTRACT FROM AUTHOR]