Good Corrosion Resistance Research Articles

Deposition of modifiable MAO-PDA coatings on magnesium alloy based on photocatalytic effect

Micro arc oxidation-Polydopamine (MAO-PDA) composite coating is a functional corrosion resistant coating formed on the surface of magnesium alloy by combining MAO to form a porous ceramic layer and the spontaneous oxidation polymerization characteristics of PDA. The MAO-PDA coating is environmentally friendly and modifiable, providing a basic film layer for achieving self-warning, self-healing, conductivity and other modification functions, which has attracted widespread attention. A new type of MAO-PDA composite coating with good corrosion resistance was deposited on the surface of magnesium alloy by photocatalysis, which expanded the application range of magnesium alloy MAO surface treatment. Surface morphology, coating adhesion and corrosion resistance of the composite coating are characterized. Combined with Density functional theory (DFT) calculation, the possible mechanism is explored. The results indicate that the MAO layer containing Mg2TiO4 exhibits fewer pores and can better deposit PDA under ultraviolet (UV) light conditions, forming a magnesium alloy MAO-PDA composite coating with good corrosion resistance and modification friendliness. Band structure calculations confirm the photocatalytic effect of Mg2TiO4 under UV irradiation. As a result of the photocatalytic effect, reactive oxygen species (ROS) were generated in the pores and on the surface of the MAO sample, thus accelerating the local deposition of PDA.

Study on microstructure, mechanical and corrosion behavior of Ti-6Al-4V titanium alloy by Keyhole gas tungsten arc welding

In this paper, 8 mm thick Ti6Al4V titanium alloy was successfully welded by keyhole gas tungsten electrode arc welding (K-TIG) technology without special edge preparation. The microstructure, mechanical properties and corrosion resistance of the joint were studied. The experimental results show that the overall weld is nail-shaped, and there are no welding defects such as porosity, cracks, and unfused sidewalls. The weld area is mainly composed of many fine acicular -like α, coarse acicular -like α and massive α intertwined with each other, and the distribution ratio of high-angle grain boundaries in the heat-affected zone and weld metal area is higher than that of the base metal. The microhardness fluctuation of each region in the welded joints is not large, and the tensile strength of the welded joints reaches 96.7 % of the base metal, and the post-weld mechanical properties are good. The K-TIG welded joints and the base metal were electrochemically analyzed, and the welded joints showed good corrosion resistance.

Improved tribological behavior of Ti-6Al-4V through a novel zirconium diffusion coating

Titanium alloys, especially Ti-6Al-4V, are widely applied in the aerospace, automotive, marine, medical, and chemical industries due to their high strength, low density, good corrosion resistance, and high-temperature performance. However, the low wear resistance of Ti-6Al-4V hinders its broader applications. In this study, the influence of five different surface modifications on the tribological behavior of Ti-6Al-4V is compared. The five surface modifications were categorized as: 1) single-step process (oxidation), 2) two-step process (oxidation+reduction), 3) three-step process (oxidation+reduction+reoxidation), 4) oxidation at reduced oxygen partial pressure, and 5) a newly developed Zr slurry diffusion coating followed by subsequent oxidation to form ZrO2-enriched TiO2 on the surface. The wear tests were performed using a Si3N4 ball counterpart with a load of 5 N at a sliding velocity of 5.25 · 10−2 m/s and with a total sliding distance of 300 m. The wear mechanism for the unmodified Ti-6Al-4V was predicted and observed to be the detachment of Si3N4 particles from the counterpart and metallic particles from the substrate, subsequent oxidation of these particles via tribochemical reactions, and the adherence of the oxidized wear debris into the substrate and counterpart surface grooves. Deep ploughing grooves were not evident in the wear tracks of any surface-modified Ti-6Al-4V materials. Instead, wear debris containing Si-rich oxides formed as a tribolayer, except for the two-step processed sample. All surface treatments led to narrower and shallower wear tracks and there was no measurable material removal for the Zr diffusion-coated sample under the investigated conditions.

Friction and corrosion characteristics of microarc oxidation/laser cladding palygorskite coating on 6061 aluminum alloy substrates

In this study, micro arc oxidation (MAO) technology was used to surface coating of 6061 aluminum (Al) disk. Then laser is used to clad palygorskite (Pal) on the surface of the MAO coating to improve the protection of the coating against the Al substrate. The laser irradiates heat onto the Pal powder, the Pal is heated and at the same time the MAO coating is affected by the heat, and the MAO coating is cooled and cured along with the Pal to form the MAO- Pal composite coating. The surface morphology, elemental composition and phase composition of the MAO-Pal coating were analyzed using scanning electron microscopy, energy spectroscopy and X-ray diffraction. And friction experiments were performed on the MAO- Pal coating. The results showed that the coefficient of friction (COF) of the MAO-Pal coating was reduced by 27 % compared to the Al substrate and 19 % compared to the MAO coating under water lubrication conditions. Through the corrosion resistance experiments, the corrosion potential (Ecorr) of the MAO- Pal coating increased by 0.197 V compared to the Al substrate and 0.280 V compared to the MAO coating, and the corrosion current density (Icorr) simultaneously decreased by three orders of magnitude compared to the Al substrate and one order of magnitude compared to the MAO coating. The MAO- Pal coating prepared by laser cladding Pal had good wear and corrosion resistance, which improved the service life and application range of Al alloy and was expected to promote the development of Al alloy in the application field.

A review of polymeric bipolar plates for proton exchange membrane fuel cells: Materials, fabrication, applications, cost analysis, and current status

Bipolar plates play a crucial role in the performance and viability of proton exchange membrane fuel cells. Polymeric composites have demonstrated their potential as alternatives to graphite and metallic materials for bipolar plates due to their good corrosion resistance, lightweight nature, flexibility, and cost-effectiveness. However, these polymeric materials often suffer from low electrical conductivity. The incorporation of various electrically conducting fillers can improve the electrical conductivity of these materials. This work presents a comprehensive review of the utilization of polymeric materials-based composites for bipolar plates for proton exchange membrane fuel cells. Various aspects related to bipolar plates in proton exchange membrane fuel cells, including materials, fabrication techniques, applications, cost analysis, and the current status of proton exchange membrane fuel cells are discussed in this work. Both thermoplastic and thermoset-based composites are explored as matrix materials for bipolar plates, along with different conducting filler/reinforcement options, and their best results are also explored. The impact of traditional as well as emerging fabrication techniques on the performance of bipolar plates is evaluated, emphasizing the need to reduce the cost of bipolar plates for the commercialization of proton exchange membrane fuel cells. Furthermore, the paper also examines the applications and current status of proton exchange membrane fuel cells in India as well as worldwide.

“Dual-armor” strategy to prepare multifunctional carbonyl iron particle with corrosion resistance, self-healing and high microwave absorbing performances

As a common and high microwave absorbing material, the application fields of carbonyl iron particle (CIP) are limited because of its poor corrosion resistance when working in harsh environments such as ocean, rainforest, or other high-humidity, high-salt places. Therefore, it is necessary to design a multifunctional CIP with good corrosion resistance and self-healing properties for ensuring its stable microwave absorbing performance. Herein, a “dual-armor” strategy is proposed to prepare multifunctional CIP (Composite particle), which is assembled with CIP coated by polyaniline (PANI/CIP) and Fe-DSe-M. Fe-DSe-M is Fe3+ responsive microcapsule whose shell contains -Se-Se-bonds and is magnetically adsorbed on the surface of PANI/CIP. PANI/CIP and Fe-DSe-M jointly undertake the function of microwave absorbing, anti-corrosion and self-healing. It is worth to note that the microwave absorbing performance of CIP after multi-functionalization has been greatly improved, and the minimum reflection loss value after accelerated corrosion is only reduced by 5.46 dB, which is much lower than PANI/CIP. These excellent properties of functional Composite particle benefit from PANI protective layer, Fe3+ responsive self-healing Fe-DSe-M and their synergistic effect. Our work provides a new approach to fabricate multifunctional microwave absorbing particle, which has a potential application in the corrosive environment.

Investigation on corrosion resistance of electroless Ni-W-P coatings co-deposited with SiO2 nanoparticles

The corrosion of materials in sea environment are generally caused by salt spray, tidal action and adhesion of marine organisms. It is necessary to ensure the materials possess the required strength and good corrosion resistance during operation. Although the existing Ni-W-P electroless plating can provide a certain degree of corrosion protection, its corrosion resistance is still limited under harsh marine condition. SiO2 nanoparticles have received extensive concern due to their excellent corrosion resistance, which has been considered as potential candidates for enhancing corrosion resistance in multicomponent electroless coatings. In this study, the electroless Ni-W-P coatings with SiO2 nanoparticles co-deposition on the Q235 substrate was prepared. The coating was characterized through scanning electron microscopy (SEM), x-ray diffraction (XRD), polarization techniques, and electrochemical impedance spectroscopy (EIS). As a result, the Ni-W-P coating co-deposited with SiO2 nanoparticles demonstrates superior corrosion resistance compared to the pure Ni-W-P coating. The surface of SiO2 nanoparticles contain three distinct bonded hydroxyl functional groups, which can influence the ionic reaction in the plating solution and the deposition of elements in the coating. After modified by PVA, it can be uniformly dispersed in the coating, and the composite coating with SiO2 nanoparticles co-deposited is transformed into a nanocrystalline structure. The even distribution of SiO2 nanoparticles fill the defects within the coating, leading to a reduction in porosity, permeability, and susceptibility to penetration of corrosive media. Concurrently, the nanoparticles facilitate surface passivation, forming a stable interface with substrate and coating that inhibits electrochemical reactions and diminishes the rate of self-corrosion reactions. The good and stable corrosion resistance is achieved at the SiO2 concentration of 9 g l−1 and PVA concentration of 1.08 g l−1. These findings offer valuable insights for addressing corrosion challenges in the field of marine engineering.

The structure evolution of austenite stainless steel with pre-shot peening during plasma nitriding

Abstract Austenitic stainless steel is a very promising metal bipolar plate for proton exchange membrane fuel cells (PEMFC), which has advantages such as high mechanical strength, easy processing, and low cost. However, it is prone to corrosion in the acidic environment of PEMFC, which can have adverse effects on its lifespan and conductivity. By adopting a composite modification method to generate a dense nitride structure on the surface of 304 stainless steel bipolar plates, the corrosion resistance of the bipolar plate substrate can be improved. In this paper, shot peening pretreatment and plasma nitriding hybrid modification methods were employed to improve nitriding efficiency and reduce nitriding critical temperature, which generated a modified layer with good corrosion resistance on the surface of 304 austenitic stainless steel.

Effect of pulse electroplating parameters on the morphology and corrosion resistance of Ag plating coating

Pulse electroplating technology has the characteristics of fine grain and good corrosion resistance. In order to ensure the good application of electroplated silver cone cavity in solar radiation detector. The effects of three process parameters, including average current density (0.4–1 A dm−2), pulse on-time (0.2–1.8 ms) and pulse off-time (0.8–4.8 ms), on the deposition rate, appearance and corrosion resistance of silver coating were studied by control variates. The surface morphology and composition of silver coatings were studied by scanning electron microscope (SEM), laser confocal microscopy and energy dispersive x-ray spectrometer (EDX). The corrosion resistance of silver coating in 3.5 wt% NaCl solution (pH=5.5) was studied by polarisation curves and electrochemical impedance spectroscopy. The results show that pulse electroplating takes advantage of the dynamic change of current to influence the size of deposited particles and the degree of densification of the coating by precisely adjusting the pulse plating parameters, and ultimately obtains the coating with excellent morphology. The optimal parameters are: average current density 0.6 A dm−2, pulse on-time 1.2 ms, pulse off-time 1.8 ms. The silver coating prepared under process conditions has excellent corrosion resistance (7059 Ω cm−2). The surface crystal grain is dense, without obvious defects.

Mechanical and wear characteristics of aluminium-7075/graphene/TiB2 prepared by stir casting

The rapid development of Aluminium composites with advanced hybrid materials is increasing due to increasing demand. This composite material is used in many applications in the aerospace and automotive industries due to its lightweight, good corrosion resistance and high thermal resistance. To meet this demand, this study focused on the development of Al-7075 alloy reinforcements containing TiB2 and graphene, using Aluminium-7075 as the base material, mixed with TiB2 and graphene to measure and improve mechanical and tribological properties by using stir casting technique, with the proposed graphene content of 1%, 2% and 3% and TiB2 content varying between 1 to 15% of its overall weight. With the addition of TiB2 and graphene properties such as hardness, tensile strength, impact strength and tribological behaviour are improved. The 12% reinforcement combination (i.e. 10% TiB2 and 2% Gr) exhibit better tensile strength, hardness and wear resistance. Microstructure and phase characterization of the composite material are analyzed using scanning electron microscopy (SEM) and x-ray diffraction (XRD) techniques. A microstructure evaluation is employed to justify the homogenous dispersal and the existence of reinforced particles. To ensure the quality and reliability of products made from these alloys, destructive tests are often conducted to evaluate their mechanical properties and behavior under different loading conditions.

Complementary corrosion protection of cast AlSi7Mg0.3 alloy using Zr-Cr conversion and polyacrylic/siloxane-silica multilayer coatings

Aluminium cast alloy AlSi7Mg0.3 is a lightweight metal commonly used in automotive, aeronautical and mechanical applications. It has good corrosion resistance but, under harsh operative conditions, would benefit from additional protection. In this study, a corrosion-protective multilayer coating system for AlSi7Mg0.3 based on hexafluoro-zirconated trivalent chromium coating (Zr-CrCC) and polyacrylic/siloxane-silica (PEHA-SS) coating was developed. The Zr-CrCC was formed by immersion of the substrate in a commercial conversion bath (SurTec® 650). PEHA-SS synthesis was based on organic precursors (2-ethylhexyl acrylate and [3-(methacryloyloxy)propyl]trimethoxysilane) and an inorganic precursor, tetraethyl orthosilicate. After deposition on AlSi7Mg0.3, each coating was first characterised individually, followed by the analysis of the multilayer using scanning electron microscopy and energy-dispersive X-ray spectroscopy. The adhesion of the coatings was evaluated with a cross-hatch cut test. The corrosion studies in sodium chloride solution using electrochemical impedance spectroscopy and salt spray testing showed that the multilayer system is superior to individual Zr-CrCC and PEHA-SS coatings. After 4 months in 0.1 M NaCl, the multilayer-coated samples exhibited the impedance at 10 mHz in the range of GΩ cm2, while scribed samples withstood the corrosion attack in a salt spray chamber for one week. Thus, albeit only about 100 nm thick, the Zr-CrCC deposited between the substrate and a 9-micrometre thick barrier sol-gel PEHA-SS coating acts as an active corrosion protection interlayer and contributes to the overall protectiveness of the multilayer system.

An In-Depth Investigation of the Effects of Tungsten Inert Gas Welding Process Parameters on Hardness and Corrosion Resistance of 2205 DSS Weldments: New Design of Experiment Parametric Studies and Optimization

The aim of this work is to examine and analyze, using response surface methodology, how the TIG welding process parameters of welding current (WC), welding speed (WS), and N2 with argon as shielding gas affect the hardness and corrosion resistance of 2205 DSS weldments. Due to the equal amounts of ferrite and austenite phases and alloying elements, duplex stainless steel DSS offers good mechanical properties and corrosion resistance. The mechanical characteristics and resistance to corrosion of the weld zone, as well as the heat-affected zone of the DSS, are, however, disturbed as a result of the welding process since it changes the distribution of these two phases and also the alloy is thermally disturbed. Therefore, in this work, an in-depth investigation of the effects of the above-mentioned parameters on the DSS quality has been performed. Results showed that increasing welding current while decreasing welding speed, which corresponds to the highest heat input, led to lower critical pitting potential and weld zone hardness but higher heat-affected zone hardness. The same results were obtained for decreasing welding current while increasing welding speed, which correspond to the lowest heat input. However, the addition of a small percent (%) of N2 to argon shielding gas resulted in increasing the critical pitting potential and decreasing the hardness in welds and heat-affected zones. Numerically, the RSM planned experimental results showed that an optimum welding current of 175A, welding speed of 170 mm/min, and 10% N2 with argon as shielding gas maximized the critical pitting potential up to 318 mV and optimized the hardness of the weld and heat-affected zone to about base metal hardness of 288 and 286 HV, respectively.

Assessment of HVAF thermally sprayed coatings: Unraveling microstructural, electrochemical, and tribological performance using glass former Fe-Cr-Mo-Nb-B feedstock powder

In this paper the microstructural features of the glass former Fe68Cr8Mo4Nb4B16 coatings are unveiled and related to their electrochemical and tribological responses. The coating was mostly glassy with some embedded borides (M3B2, M2B-tetragonal; M being the metallic elements of the alloy) and ferrite. The tribological behavior of the HVAF coated sample, characterized by a thickness of about 200 µm, ∼6% porosity and a Vickers hardness of 357 HV0.5, was assessed in a sphere-on-plate configuration, revealing a specific wear rate of approximately 5 ×10−4 mm3∙N−1m−1. The wear mechanism was dominated by delamination caused by fragile intersplats. The corrosion resistance of HVAF coatings was evaluated in 0.6 M NaCl solution and compared with the results obtained for the crystalline Fe68Cr8Mo4Nb4B16 ingot, produced by melting in an induction furnace, and for the AISI 1020 steel substrate. The HVAF coating showed satisfactory corrosion resistance compared to the carbon steel substrate and the crystalline ingot, with the highest corrosion potential, Ecorr, values (−533 mVSCE) and the lowest corrosion current density, icorr, (10−6 A∙cm−2) followed by a clear passivation window upon anodic polarization in 0.6 M NaCl solution. Evaluations of HVAF coating showed a higher glassy content compared to the gas-atomized feedstock powders. This suggests that during spraying, certain particles were molten and experienced cooling rates adequate to inhibit crystallization, resulting in the freezing of the supercooled liquid. This phenomenon contributes to the good corrosion resistance observed in the present work and offers an opportunity to enhance the electrochemical behavior of HVAF coatings.

High‐temperature KCl‐induced corrosion of high Cr and Ni alloys investigated by in‐situ diffraction

AbstractHigh‐temperature KCl‐induced corrosion in laboratory air was observed in situ utilizing X‐ray diffraction. High Cr‐containing model alloys (Fe‐13Cr, Fe‐18Cr‐12Ni, and Fe‐25Cr‐20Ni) were coated with KCl and exposed to dry air at 560°C. KCl‐free alloys were studied in the equivalent atmosphere as a reference. After exposure to KCl‐free environments, all alloys showed the formation of very thin oxide layers, indicating good corrosion resistance. In contrast, KCl‐bearing alloys showed distinct damage after exposure.

Anticorrosion and adhesion performance of a monolayer and double layer silane-epoxy coating systems applied on carbon steel

Carbon steel is one of the widely used metallic material, although its limited corrosion resistance. To improve its anti-corrosion performance, organic coatings such as epoxy have been an excellent option due to their barrier mechanism. Nevertheless, the elevated brittleness and porosity observed in this type of coating, coupled with the weak bonding interface between epoxy and carbon steel, significantly hampered their protective capabilities. The organofunctional silanes are candidates to be used as pre-treatment between epoxy coating and carbon steel interface because of their good corrosion resistance but as a limitation they can present small pores and microcracks.Therefore, the anticorrosive and mechanical properties of silane films can be adapted and further improved by strengthening the coatings through some modifications, such as the incorporation of green corrosion inhibitors into the film, reducing the access of aggressive species to the metal. In this context, the objective of this research is to evaluate the adhesion and anticorrosive properties of an epoxy-based organic coating pre-treated with a silane film obtained by tetraethoxysilane (TEOS) with γ-glycidoxypropyltrimethoxysilane (GPTMS) modified with the garlic peel powder as a corrosion inhibitor (Allium sativum L.). The investigation of the surface features as morphology and the corrosion resistance of the silane-epoxy coatings were studied by scanning electron microscope (SEM) and electrochemical characterization techniques, such as, electrochemical impedance spectroscopy (EIS), linear and potentiodynamic polarization. Also, the coating adherence was evaluated by pull-off tests. The results of the EIS showed that all samples coated with silane+ epoxy coating have better anticorrosion performance than the sample coated with just epoxy painting. Besides, SEM images showed that the silane film improved the cohesion between substrate and coating system, with the clear appearance of delamination in the system silane free. In general, the results of these different techniques indicate that the film modified with the natural inhibitor has improved anticorrosive properties compared to the film without silane or natural green inhibitors.

Tribocorrosion Evaluation of AISI 431 Coated With Tungsten Oxynitride

Abstract Tribocorrosion is a phenomenon present in a wide variety of processes; hence, understanding the tribocorrosion behavior of different systems is essential to being able to design robust and reliable systems. This has led us to investigate the tribocorrosion behavior of AISI 431 steel, a stainless steel commonly used for manufacturing mechanical pieces. The response to tribocorrosion was evaluated for the AISI 431 steel in contact with an aqueous solution of citric acid, a solution commonly used in the food industry. The tests were carried out using samples of steel uncoated and coated with tungsten oxynitride in a pin-on-disc configuration using a tailored tribocorrosion cell. The uncoated AISI 431 presented good wear and corrosion resistance but presented tribocorrosion degradation, where the growth of the passivation film and the mechanical removal of such film were the driving factors for the tribocorrosion process. Furthermore, when the steel was coated with the tungsten oxynitride film, we found that the surface presented a better resistance to wear, corrosion, and tribocorrosion. Such findings open a great opportunity for the use of these types of coatings to protect systems against tribocorrosion.

Production of sub-micron-sized high-entropy alloy particles and nanoparticles via pulsed laser ablation of CrMnFeCoNi targets in water

High-entropy alloys (HEAs) are a class of materials known for their unique properties, including high strength, excellent wear resistance, and good corrosion resistance. Sub-micron- and nanosized HEA particles were fabricated via pulsed laser ablation in liquid using a Cantor alloy target. The Cr20Mn20Fe20Co20Ni20 target was immersed in pure water and ablated using a focused nanosecond-pulsed Nd: YAG laser. A dark solution containing HEA particles was obtained which was stable for about one week before agglomeration and precipitation was observed. The diameters of the obtained particles ranged from several tens of nanometers to several hundred nanometers. Increasing the laser power resulted in higher particle concentration and an increase in the intensity of UV-vis absorption spectra. Electron diffraction was used to confirm that the composition of the particles was close to that of the Cantor alloy, although the concentrations of Cr and Mn were slightly deficient. There was also a weak dependence of the composition on laser power, and all the particles also contained oxygen. Selected area electron diffraction revealed that the composition varied spatially within some particles and that they are mainly polycrystalline. This work shows that HEA particles can be quickly, safely, and effectively manufactured using liquid-based laser ablation, opening the pathway for mass manufacture and disruptive applications in, e.g., catalysis or tribology.

THE EFFECT OF LASER OSCILLATING WELDING ON FORMATION AND PROPERTIES OF TITANIUM ALLOY

Titanium alloys are widely used in aerospace and other fields due to their advantages of low density, high specific strength and good corrosion resistance. Laser oscillating welding is an innovative process in the realm of welding technology. In this study, two laser oscillating welding methods (circular and linear) were employed to analyze the influence of different oscillation parameters on the formation of titanium alloy. The results indicate that the oscillation frequency has a significant impact on weld formation. The laser scanning trajectory also affects weld formation, with circular and linear scanning trajectories resulting in better weld quality. Finally, the effects of oscillation modes on the microstructure and properties of laser oscillating welding titanium alloy were investigated based on optimized process parameters. Among them, circular laser oscillating welding of titanium alloy exhibits higher tensile strength, with a maximum tensile strength of up to 1188.3[Formula: see text]MPa.

The fracture energy of concrete reinforced with double-helix macro basalt-fibre-reinforced polymer fibre

A novel type of fibre – double-helix macro basalt-fibre-reinforced polymer (DHM BFRP) fibre – is proposed to increase the cracking, tensile strength and ductility of concrete. The novel fibre is made from micro basalt fibres and resin, twisted together in a double helix. BFRP offers high tensile strength, good corrosion resistance and low cost, while the double-helix geometry provides excellent bond–slip performance between the fibre and the concrete matrix. Three-point bending (3PB) tests were conducted to measure the fracture energy of concrete reinforced with DHM BFRP fibres. The influences of fibre orientation (aligned and random) on cracking load, peak load, flexural strength and fracture energy were analysed. Compared with random DHM BFRP fibres, aligned fibres resulted in a 26.4% higher fracture energy and a 29.7% increase in flexural strength. Finite-element models of the 3PB tests were established using LS-Dyna. The Karagozian & Case concrete model was calibrated based on the fracture energy results to obtain a material model of fibre-reinforced concrete (FRC) considering fibre orientation. The errors between the simulated and tested maximum loads for 3PB tests of plain concrete, FRC and fibre-reinforced self-compacting concrete were 8.3%, 4.0% and 11.4%, respectively, indicating that the simulated and test results were in good agreement. This study provides a theoretical foundation and technical support for practical engineering applications of DHM BFRP fibres.

Effect of H+ pre-irradiation on irradiation hardening and microstructure evolution of FeCoCrNiAl0.3 alloy with He2+ irradiation

FeCoCrNiAlx-based high entropy alloys (HEAs) exhibit excellent high-temperature strength, good radiation tolerance and corrosion resistance. However, studies on light-ion irradiation damage are relatively lacking. The influence of hydrogen and helium effect on HEAs deserves further study, given their complex interaction during different sequence irradiation at different irradiation conditions. In the present study, FeCoCrNiAl0.3 HEA was irradiated under two different modes at 723 K, one is single He2+ and the other is pre-iradiation of H+ followed by He2+. Microstructure evolution and irradiation hardening were studied by transmission electron microscopy and nanoindentation technique. There is no distinct difference of the irradiation hardening rate between sequential H+-He2+ and single He2+ irradiated samples. A large number of irradiation-induced nano-defects were observed after pre-irradiation of H+, which act as sinks to trap the subsequent helium atoms in the H+-He2+ irradiated sample. Fine helium bubbles and dislocation loops with high density dispersed in both irradiated samples. Compared with single He2+ irradiation, pre-irradiation of H+ resulted in a decrease in bubble density and an increase in loop density in H+-He2+ irradiated sample, but had little effect on their size. It is speculated that the critical concentration of bubble formation originating from H-He-V clusters is supposed to be higher than that of HeV clusters at elevated temperatures in FeCoCrNiAl0.3 alloy, leading to the aggregation and redistribution of He atoms at the H-He-V clusters rather than the formation of stable bubble nucleus after succeeding He2+ irradiation. The influence of pre-irradiation of H+ on FeCoCrNiAl0.3 alloy on the formation of helium bubbles and the relationship between bubble, loop and irradiation hardening are discussed.