Oriented exchange-coupled L10-FePt/Co core-shell nanoparticles with variable Co thickness

Exchange-coupled core–shell nanoparticles are expected to be the new generation of permanent magnets, where the orientation of the hard magnetic phase is supposed to play a key role in improving their magnetic performance. In this work, L1₀-FePt/Co core–shell nanoparticles with Co thickness ranging from 0.6 to 2.2 nm have been synthesized by a seed-mediated growth method. The exchange coupling effect between the hard core and soft shell led to a 60% improvement of the maximum magnetic energy product ((BH)_max), compared with the pure L1₀-FePt core. By tuning the amount of precursor, nanoparticles with different Co shell thicknesses were synthesized. Furthermore, the L1₀-FePt/Co core–shell nanoparticles were dispersed in epoxy resin and oriented under an external magnetic field. The (BH)_max of the anisotropic nanocomposite magnet with a Co thickness of 1 nm is 7.1 MGOe, enhanced by 117% compared with the isotropic L1₀-FePt magnet, which paves the way for the development of high-performance permanent magnets for energy conversion applications.

With the increase of Co layer thickness, the outer layer Co and the core gradually decoupled.     

Chemical synthesis of Nd2Fe14B/Fe–Co nanocomposite with high magnetic energy product

Nd₂Fe₁₄B is one of the most popular permanent magnets (PMs) possessing the best energy product (BH)_max among the common PM materials. However, exchange-coupled nanocomposite magnets fabricated by embedding nanostructures of soft-phase magnetic materials into a hard-phase magnetic matrix manifest higher remanence and a higher energy product. Here we present the fabrication of exchange coupled Nd₂Fe₁₄B/Fe–Co magnetic nanocomposites using gel-combustion and diffusion–reduction processes. Pre-fabricated CoFe₂O₄ nanoparticles (NPs) of ∼5 nm diameter were incorporated into a Nd–Fe–B oxide matrix during its synthesis by gel-combustion. The obtained mixed oxide was further processed with oxidative annealing at 800 °C for 2 h and reductive annealing at 900 °C for 2 h to form a Nd₂Fe₁₄B/Fe–Co nanocomposite. Nanocomposites with different mol% of soft-phase were prepared and characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and physical property measurement system (PPMS) to study their crystalline phase, morphology and magnetic behavior. Addition of 7.7 mol% of soft-phase was found to be optimum, producing a coercivity (H_c) of 5.6 kOe and remanence (M_r) of 54 emu g⁻¹ in the nanocomposite.

Nd₂Fe₁₄B is one of the most popular permanent magnets (PMs) possessing the best energy product (BH)_max among the common PM materials.     

Sprayable copper and copper–zinc nanowires inks for antiviral surface coating

Copper alloys are known for their high antimicrobial efficacy. Retrofitting high-touch surfaces in public space with solid copper components is expensive and often impractical. Directly coating copper onto these high-touch surfaces can be achieved with hot or cold spray, but the procedure is complicated and requires special equipment. This article reports on the development of sprayable copper and copper–zinc nanowire inks for antiviral surface coating applications. Our results show that copper nanowires inactivate the SARS-CoV-2 virus faster than bulk copper. And a trace amount of zinc addition has a significant effect in enhancing the virucidal effect. More importantly, these nanowire inks are sprayable. They can be easily applied on high-touch surfaces with a spray can. When combined with common chemical disinfectants, the copper-based nanowire ink spray may prolong the disinfecting effect well after application.

SEM and TEM images of copper and copper–zinc nanowires that are sprayable for antiviral surface coating.     

Facile synthesis of a hollow Ni–Fe–B nanochain and its enhanced catalytic activity for hydrogen generation from NaBH4 hydrolysis

A hollow Ni–Fe–B nanochain is successfully synthesized by a galvanic replacement method using a Fe–B nanocomposite and a NiCl₂ solution as the template and additional reagent, respectively. Both the concentration of Ni and the morphology of the resulting Ni–Fe–B alloy are controlled by varying the duration of the replacement process during the synthesis. The Ni–Fe–B sample synthesized for 60 min (Ni–Fe–B-60) shows the best catalytic activity at 313 K, with a hydrogen production rate of 4320 mL min⁻¹ g_cat⁻¹ and an activation energy for the NaBH₄ hydrolysis reaction of 33.7 kJ mol⁻¹. The good performance of Ni–Fe–B-60 towards the hydrolysis of NaBH₄ can be ascribed to both hollow nanochain structural and electronic effects. Furthermore, the effects of temperature, catalyst amount, and concentration of NaOH and NaBH₄ on the hydrolysis process are systematically studied, and an overall kinetic rate equation is obtained. The hollow Ni–Fe–B nanochain catalyst also shows good reusability characteristics and maintained its initial activity after 5 consecutive cycles.

A hollow Ni–Fe–B nanochain is successfully synthesized by a galvanic replacement method using a Fe–B nanocomposite and a NiCl₂ solution as the template and additional reagent, respectively.     

A simple strategy to prepare a layer-by-layer assembled composite of Ni–Co LDHs on polypyrrole/rGO for a high specific capacitance supercapacitor

A facile and novel electrode material of nickel–cobalt layered double hydroxides (Ni–Co LDHs) layered on polypyrrole/reduced graphene oxide (PPy/rGO) is fabricated for a symmetrical supercapacitor via chemical polymerization, hydrothermal and vacuum filtration. This conscientiously layered composition is free from any binder or surfactants which is highly favorable for supercapacitors. The PPy/rGO serves as an ideal backbone for Ni–Co LDHs to form a free-standing electrode for a high-performance supercapacitor and enhanced the overall structural stability of the film. The well-designed layered nanostructures and high electrochemical activity from the hexagonal-flakes like Ni–Co LDHs provide large electroactive sites for the charge storage process. The specific capacitance (1018 F g⁻¹ at 10 mV s⁻¹) and specific energy (46.5 W h kg⁻¹ at 464.9 W kg⁻¹) obtained for the PPy/rGO|Ni–Co LDHs symmetrical electrode in the current study are the best reported for the two-electrode system for PPy- and LDHs-based composites. The outstanding performance in the prepared LBL film is a result of the LBL architecture of the film and the combined effect of redox reaction and electrical double layer capacitance.

A facile and novel electrode material of nickel–cobalt layered double hydroxides (Ni–Co LDHs) layered on polypyrrole/reduced graphene oxide (PPy/rGO) is fabricated for a symmetrical supercapacitor via chemical polymerization, hydrothermal and vacuum filtration.     

Polarization behavior of Pb–Co powder-pressed alloy for electrowinning

In this study, Pb–Co powder-pressed alloy was fabricated and used as a suitable anode material to replace Pb–Ca–Sn alloy in electrowinning. The Pb–Co anodes and the traditional Pb–Ca–Sn alloy on the electrochemical properties are investigated in a 160 g L⁻¹ H₂SO₄ solution at 35 °C using galvanostatic polarization, electrochemical impedance spectroscopy and Tafel test. Thereafter, the anodic oxide layer is observed by energy dispersive X-ray spectroscopy along with scanning electron microscopy and X-ray diffractometry. The results show that the potential and oxygen evolution over-potential of the anodes exhibit a declining trend with increasing the fraction of Co. The anode potential of the Pb-2 wt% Co is approximately 170 mV lower than that of Pb–Ca–Sn alloy and reaches a stable value of 1.291 V at 35 °C, which shows good electrocatalytic performance and commercial application prospect.

In this study, Pb–Co powder-pressed alloy was fabricated and used as a suitable anode material to replace Pb–Ca–Sn alloy in electrowinning.     

Effect of cobalt addition on the structure and properties of Ni–MCM-41 for the partial oxidation of methane to syngas

A one-step hydrothermal crystallization method was used to synthesize Co–Ni–MCM-41 catalysts for the partial oxidation of methane to syngas reaction. Co was added as an assistant in the synthesis process. The formation of a Ni–Co alloy decreased the damage of Ni ions to the framework of MCM-41. The Ni–Co alloy introduced more Ni into the channel exposing more active sites. The properties of the synthesized catalysts were characterized by XRD, N₂ adsorption–desorption, TEM, ICP, FT-IR, H₂-TPR, XPS and TGA techniques. Co–Ni–MCM-41 catalysts showed superior catalytic performance and sintering resistance than Ni–MCM-41 catalyst without Co. The Ni–Co alloy inhibited the formation of the NiO, thus reducing the sintering of the catalyst. The result was attributed to higher metal dispersion and more regular pore structure of the Co–Ni–MCM-41 catalysts. When the Co content was 1%, a conversion of 88% and selectivity of 87% was achieved.

The Ni–Co alloy confined within MCM-41 improved dispersibility and the stability of Ni.     

Flowery nickel–cobalt hydroxide via a solid–liquid sulphur ion grafting route and its application in hybrid supercapacitive storage

In our research, a two-step solid–liquid route was employed to fabricate flowery nickel–cobalt hydroxide with sulphur ion grafting (Ni1Co2–S). The utilization of NaOH/agar and Na₂S/agar could efficiently retard the release rates of OH⁻ or S²⁻ ions at the solid–liquid interface due to strong bonding between agar hydrogel and these anions. Ni1Co2–S generally displays ultrathin flowery micro-frame, ultrathin internal nanosheets and expanded pore size. Besides, the introduction of suitable sulphide species into nickel–cobalt hydroxide could improve its conductivity due to the lower band gap of Ni–Co sulphide. The supercapacitive electrode Ni1Co2–S presented capacitance of 1317.8 F g⁻¹ (at 1 A g⁻¹) and suitable rate performance (77.9% at 10 A g⁻¹ and 59.3% at 20 A g⁻¹). Furthermore, a hybrid supercapacitor (HSC) was developed utilizing positive Ni1Co2–S and negative activated carbon electrodes. As expected, the HSC device exhibited excellent specific capacitance (117.1 F g⁻¹ at 1 A g⁻¹), considerable energy densities (46.7 W h kg⁻¹ at 0.845 kW kg⁻¹ and 27.5 W h kg⁻¹ even at 9 kW kg⁻¹) and suitable cycling performance, which further illuminated the high energy storage capacity of Ni1Co2–S.

The Ni1Co2–S material fabricated via a solid–liquid route achieves high-performance supercapacitive storage.     

Electrodeposited nickel–graphene nanocomposite coating: effect of graphene nanoplatelet size on its microstructure and hardness

In this study, the effect of graphene nanoplatelet (GNP) size on the microstructure and hardness of the electrodeposited nickel–graphene nanocomposite coatings were investigated. GNPs with different sizes were prepared by using a high energy ball milling technique. The experimental result revealed the high energy ball milling technique could reduce the size, increase the surface area, and improve the dispersion ability of GNPs. The microstructure, hardness, and components of the nanocomposite coatings were greatly affected by GNP sizes. The highest microhardness was measured to be 273 HV for the nanocomposite coatings containing 5 h-milled GNPs, which is increased up to ∼47% compared to pristine Ni coating. The enhancement in the hardness is attributed to the uniform dispersion of the small GNP sizes inside the Ni matrix and the Ni grain size reduction when using milled GNPs.

The effect of graphene nanoplatelet size on the microstructure and hardness of electrodeposited nickel–graphene nanocomposite coatings was investigated.     

Electrochemical performance of porous Ni-alloy electrodes for hydrogen evolution reaction from seawater electrolysis

The hydrogen evolution reaction in seawater is investigated using porous Ni–Cr–Fe, Ni–Fe–Mo, Ni–Fe–C and Ni–Ti electrodes, prepared by elemental powder reactive synthesis methods. The open porosity of the four kinds of electrode materials is 23.05%, 20.47%, 25.27%, and 29.05%, respectively. The electrochemical performance of the four kinds of electrodes has been researched by polarization measurement, cyclic voltammetry and electrochemical impedance spectroscopy. The preliminary results demonstrate that the porous Ni–Cr–Fe electrode has superior catalytic activity and relatively good long-term stability for hydrogen evolution reaction in seawater. The high efficiency and reasonable stability of the porous Ni–Cr–Fe electrode catalyst demonstrate its promising applications in the rising hydrogen revolution.

The hydrogen evolution reaction in seawater is investigated using porous Ni–Cr–Fe, Ni–Fe–Mo, Ni–Fe–C and Ni–Ti electrodes, prepared by elemental powder reactive synthesis methods.     

One-step hydrothermal synthesis of Ni–Fe–P/graphene nanosheet composites with excellent electromagnetic wave absorption properties

Ni–Fe–P nanoparticles/graphene nanosheet (Ni–Fe–P/GNs) composites were successfully synthesized by a simple one-step hydrothermal method. Specifically, Ni²⁺ and Fe²⁺ were reduced by using milder sodium hypophosphite as a reducing agent in aqueous solution. SEM and TEM images show that a large number of Ni–Fe–P nanoscale microspheres are uniformly deposited on graphene nanosheets (GNs). At the thickness of 3.9 mm, the minimum reflection loss (RL) of Ni–Fe–P/GNs reaches −50.5 dB at 5.3 GHz. In addition, Ni–Fe–P/GNs exhibit a maximum absorption bandwidth of 5.0 GHz (13.0–18.0 GHz) at the thickness of 1.6 mm. The significant electromagnetic absorption characteristics of the Ni–Fe–P/GN composites can be attributed to the addition of magnetic particles to tune the dielectric properties of graphene to achieve good impedance matching. Therefore, Ni–Fe–P/GN is expected to be an attractive candidate for an electromagnetic wave absorber.

Ni–Fe–P nanoparticle/graphene nanosheet composites synthesized by a one-step hydrothermal method have excellent performance in the field of electromagnetic wave absorption, with a minimum reflection loss of −50.5 dB and a maximum effective absorption bandwidth of 5 GHz.     

Nanoscale tungsten nitride/nitrogen-doped carbon as an efficient non-noble metal catalyst for hydrogen and oxygen recombination at room temperature in nickel–iron batteries

A nanoscale tungsten nitride/nitrogen-doped carbon (WN/NC) catalyst was synthesized through a facile route, and it exhibited efficient catalytic performance for hydrogen and oxygen recombination at room temperature with an average catalytic velocity of 140 μmol h⁻¹ g_cat⁻¹ and long catalytic life of 954 660 s without decay in the catalytic performance. With the WN/NC catalyst, a nickel–iron battery could be sealed and maintenance-free, and it also exhibited low cost; thus, the nickel–iron battery can be used for large-scale energy storage systems in rural/remote areas.

A nickel–iron battery with nanoscale WN/NC catalyst can be used for large-scale energy storage systems in rural/remote areas.     

Highly cost-effective platinum-free anion exchange membrane electrolysis for large scale energy storage and hydrogen production

Anion exchange membrane (AEM) electrolysis eradicates platinum group metal electrocatalysts and diaphragms and is used in conventional proton exchange membrane (PEM) electrolysis and alkaline electrolysis. It can produce pressurised hydrogen by using low cost non-noble metal catalysts. However, the performances are still lower than that of the conventional PEM electrolysis technology. In this study, we addressed the performance issue by using a novel combination of Ni–Fe–O_x for oxygen evolution reaction (OER) and Ni–Fe–Co hydrogen evolution reaction (HER) electrodes with a PBI anion exchange membrane. The Ni–Fe–O_x and Ni–Fe–Co electrodes exhibit exceptionally high catalytic activity, requiring over potentials that are as low as 236 and 84 mV dec⁻¹, respectively, for OER and HER to occur. These electrocatalysts exhibits excellent durability which can be used as oxygen evolution and hydrogen evolution catalysts for long term electrolysis. The high rate capability of 1000 mA cm⁻² at 1.9 V and 60 °C demonstrates the potential of the combined membrane electrode assembly. The best performance, which is comparable to those of commercial PEM electrolysis systems, is thus an affordable alternative to this technology. In addition to that, the AEM electrolysis is promising on a multi-scale level for long-term hydrogen production.

Anion exchange membrane (AEM) electrolysis eradicates platinum group metal electrocatalysts and diaphragms and is used in conventional proton exchange membrane (PEM) electrolysis and alkaline electrolysis.     

Soybean straw biomass-derived Fe–N co-doped porous carbon as an efficient electrocatalyst for oxygen reduction in both alkaline and acidic media

The development of highly efficient oxygen reduction reaction (ORR) catalysts is of great significance for the large-scale commercialization of fuel cells. In this work, honeycomb-like Fe–N co-doped porous carbon materials (Fe–N–PC) were prepared through a facile one-step pyrolysis strategy using soybean straw biomass as the precursor. The obtained Fe–N–PC catalyst exhibits excellent ORR performance with an onset potential of 0.989 V and a half-wave potential of 0.854 V in alkaline conditions, which positively shift only by 5 mV and 27 mV, respectively than those of the commercial Pt/C catalyst. Furthermore, the onset potential and the half-wave potential of the Fe–N–PC catalysts are up to 0.886 V and 0.754 V, respectively, under acidic conditions, which are superior to those of many other Fe, N-doped electrocatalysts. The ORR process can be regarded as a four-electron transfer process based on RRDE measurements. Moreover, the Fe–N–PC catalyst also shows greater stability and satisfactory methanol tolerance than the Pt/C catalyst. The superior electrocatalytic performance of Fe–N–PC may be attributed to the abundant nanoporous structure, large BET surface area, and Fe–N co-doping, which provide abundant and highly efficient active sites.

Fe–N co-doped porous carbon (Fe–N–PC) was prepared by a facile one-step pyrolysis strategy using biomass soybean straw as the precursor, which exhibits outstanding electrocatalytic performance for ORR, excellent stability and methanol tolerance.     

Promoted dispersion and uniformity of active species on Fe–Ce–Al catalysts for efficient NO abatement

Fe–Ce–Al catalysts were synthesized by the co-precipitation method (labeled as Fe–Ce–Al–P), co-impregnation method (Fe–Ce–Al–I), and direct mixing method (Fe–Ce–Al–M), respectively, and used for effective removal of NO. The synthesized catalysts were characterized by many methods including N₂ physisorption, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), NH₃-temperature programmed desorption (NH₃-TPD), H₂-temperature programmed reduction (H₂-TPR), high-resolution transmission electron microscopy (HR-TEM), and energy dispersive spectroscopy (EDS) mapping. The results show that the synthesis methods greatly influence the catalytic performance of catalysts. The Fe–Ce–Al–P catalyst prepared by the co-precipitation method yields the highest catalytic performance, while the Fe–Ce–Al–I and Fe–Ce–Al–M catalysts exhibit relatively low catalytic activity. The co-precipitation method can promote the accumulation and dispersion of more surface active species on the catalyst surface, and provide smaller particle size of active species and generate more uniform particle size distribution, while these characteristics can''t be obtained by the co-impregnation method and direct mixing method. Moreover, the co-precipitation method could produce the highest surface area and enhanced redox ability and surface acidity of the catalyst, which resulted from the high dispersion and uniform distribution of surface active species. These may be the key factors to the superior catalytic performance of the Fe–Ce–Al–P catalyst.

Fe–Ce–Al catalysts were synthesized by the co-precipitation method (labeled as Fe–Ce–Al–P), co-impregnation method (Fe–Ce–Al–I), and direct mixing method (Fe–Ce–Al–M), respectively, and used for effective removal of NO.     

Systematic exploration of N,C configurational effects on the ORR performance of Fe–N doped graphene catalysts based on DFT calculations

Metal single-atom catalysts (MSATs), such as Fe–N coordination doped sp²-carbon matrices, have emerged as a promising oxygen reduction reaction (ORR) catalyst to replace their costly platinum (Pt) based counterparts in fuel cells. In this work, we employ density functional theory (DFT) to systematically discuss the electronic-structure and surface-stress effects of N, C configurations on Fe–N doped graphene in single and double vacancy. The formation energy (E_f) of Fe–N-gra dropped off with the increase of N atoms incorporated for both single and double vacancy groups. The theoretical overpotentials on Fe–N–C sites were calculated and revealed that moderate N-doping levels and doping configuration could enhance the ORR activity of Fe–N coordination structures in the double vacancy and that doping N atoms is not effective for ORR activity in single vacancy. By exploring the d-band centers, we found that ligand effects and surface tension effects contribute to the modification of the d-band centers of metal Fe atoms. An optimum Fe–N–C ORR catalyst should exhibit moderate surface stress properties and an ideal N, C ligand configuration. This study provides new insight into the effects of N atom doping in Fe–N-gra catalysts and could help guide the rational design of high-performance carbon-based ORR electrocatalysts.

An optimum Fe–N–C ORR catalyst should exhibit a moderate surface stress property and an ideal N, C ligand configurations that results in a moderate interaction between the ORR intermediates and its surface sites.     

Mulberry-like heterostructure (Fe–O–Ti): a novel sensing material for ethanol gas sensors

The gas sensors have been widely used in various fields, to protect the safety of life and property. A novel heterostructure of Fe–O–Ti nanoparticles is fabricated by hydrothermal and wet chemical deposition methods. The Fe–O–Ti nanoparticles with a large number of pores possess high surface area, which is in favour of high-performance gas sensors. Compared with pure Fe₂O₃ and TiO₂, the Fe–O–Ti composite exhibits obviously enhanced sensing characteristics, such as faster response–recovery time (T_res = 6 s, T_rec = 48 s), higher sensing response (response = 35.6) and better selectivity. The results show that the special morphology and large specific surface area of mulberry-like Fe–O–Ti heterostructures provided a large contact area for gas reactions.

The gas sensors have been widely used in various fields, to protect the safety of life and property.     

Enhancement of Fe–N–C carbon catalyst activity for the oxygen reduction reaction: effective increment of active sites by a short and repeated heating process

Controlling the formation of Fe–N–C catalytic sites is crucial to activate the oxygen reduction reaction (ORR) for realization of non-precious electrocatalysts in proton exchange membrane fuel cells (PEMFCs). We present a quantitative study on the effect of a newly obtained thermal history on the formation of Fe–N–C catalytic sites. A short and repeated heating process is employed as the new thermal history, where short heating (1 min) followed by quenching is applied to a sample with arbitrary repetition. Through electrochemical quantitative analysis, it is found that the new process effectively increases the Fe–N–C mass-based site density (MSD) to almost twice that achieved using a conventional continuous heating process, while the turn-over frequency (TOF) is independent of the process. Elemental analysis shows that the new process effectively suppresses the thermal desorption of Fe and N atoms during the initial formation stage and consequently contributes to an increase in the Fe–N–C site density. The resultant catalytic activity (gravimetric kinetic current density (0.8 V vs. RHE)) is 1.8 times higher than that achieved with the continuous heating process. The results indicate that fine control of the thermal history can effectively increase the catalytic activity and provide guidelines for further activation of non-precious ORR electrocatalysts for PEMFCs.

Controlling the formation of Fe–N–C catalytic sites is crucial to activate the oxygen reduction reaction (ORR) for realization of non-precious electrocatalysts in proton exchange membrane fuel cells (PEMFCs).     

Theoretical investigation on the effect of the ligand on bis-silylation of C(sp)–C(sp) by Ni complexes

Density functional theory is used to study the bis-silylation of alkyne catalysed by a transition metal nickel–organic complex. The active catalyst, organic ligand, reaction mechanism, and rate-determining step were discussed with regard to dynamics and thermodynamics. COD or SIPr (COD = cyclooctadiene, SIPr = 1,3-bis(2,6-diisopropyl-phenyl)-4,5-dihydroimidazol-2-ylidene) coordination with Ni will greatly reduce the energy barrier of the Si–Si insertion step, that is, ΔΔG reaches 15.5 kcal mol⁻¹. Furthermore, the structure of alkynes will change the energy barrier of the alkyne insertion step.

Density functional theory (DFT) is used to study the bis-silylation of alkynes catalyzed by a transition metal nickel–organic complex; the active catalyst, the organic ligand, the reaction mechanism, and rate-determining step are discussed in this paper.     

Mn promotes the rate of nucleation and growth of precipitates by increasing Frenkel pairs in Fe–Cu based alloys

Fe–1.0Cu (at%) and Fe–1.2Cu–2.2Mn alloys aged at 450 °C for 0.25 h, 1 h, 2 h, and 16 h after solution treatment at 900 °C for 2 h are investigated to reveal the role of the addition of Mn on the Cu precipitates in Fe–Cu based alloys. Density functional theory (DFT) total energy calculations on point defects and their influence on Cu precipitates are also performed to understand the nucleation and growth of Cu precipitates. Experiments show that addition of Mn can slightly increase the aging peak hardness by 10 HV; by using atom probe tomography (APT) and optical microscopy, we identify that the increase in hardness derives from both grain refinement and the increase of number density of precipitates. DFT calculations show that Mn increases the formation possibility of Frenkel pairs, i.e., atomic vacancy and self-interstitial atoms, and these two types of defects both serve as nucleation sites of Cu precipitates, resulting in the increase of the nucleation centers number density, which is consistent with our APT experiments on the very initial stage of aging. Moreover, calculated results show that Mn increases the density of atomic vacancies and promotes the evolution rate of Cu precipitates, which accounts for our APT experiments where precipitates in Fe–Cu–Mn grow more quickly than in Fe–Cu. Finally, we also discuss the relationship between Mn content in reactor pressure vessel steels and its irradiation damage effects.

Fe–1.0Cu (at%) and Fe–1.2Cu–2.2Mn alloys aged at 450 °C for 0.25 h, 1 h, 2 h, and 16 h after solution treatment at 900 °C for 2 h are investigated to reveal the role of the addition of Mn on the Cu precipitates in Fe–Cu based alloys.