The corrosion properties of five nonisothermally aged (NIA) Al-Zn-Mg-Cu alloys with different heating rates are studied and compared with those of the T6-treated alloys by electrochemical experiments and weight loss test. The results show that reducing the heating rate results in an increase in the corrosion resistance of the alloy. The aging treatment at a heating rate of 10 degrees C/h results in an alloy with an excellent corrosion resistance and a low corrosion current density. Additionally, the hardness of the alloy is similar to that of the alloy treated with T6. Coarse precipitates are obtained by 10 degrees C/h aging treatment, with the grain boundaries (GBs) transferring to intermittent phases with narrow precipitation-free zones (PFZs). Therefore, this approach effectively prevents anodic dissolution and improves the corrosion resistance of the alloy. These findings suggest that NIA can enhance the mechanical properties and corrosion resistance of an alloy. Additionally, the 10 degrees C/h aging process reduces the processing time by approximately 50 %, compared to that of the T6 treatment, offering a costeffective alternative. These results provide valuable insights into the processing of large aluminium components.

The current investigation delves into the influence of varying cooling rates, encompassing water, rapid quenching oil, and air, on the quench crack susceptibility (QCS) of disc springs. The assessment reveals that the average martensite lath width under water, oil, and air cooling conditions measures 0.61 μm, 0.66 μm, and 1.12 μm, respectively. Correspondingly, the residual austenite content amounts to 6.9

Cast high-entropy alloys are frequently found to have large internal tensions, compositional segregation, and shrinkage defects, which can directly prevent them from performing as intended. Proper heat treatment can modify the internal structure of an alloy and enhance its overall performance. This study describes a new nonequiatomic proportional cast Co 40 Cr 20 Ni 30 Al 4.5 Ti 5 Mo 0.5 high-entropy alloy prepared by a vacuum induction melting technique. The impacts of different annealing temperatures (700, 800, 900, and 1000 degrees C) on the microstructure evolution mechanism, mechanical properties and corrosion behaviour of the alloy are systematically examined. The results show that the heat treatment can successfully improve the overall mechanical properties and corrosion resistance of high-entropy alloys while suppressing casting defects. The alloy exhibits the best overall mechanical properties after annealing at 700 degrees C, with a yield strength of 923 MPa and a tensile strength of 1090 MPa. After annealing at a temperature of 800 degrees C, the alloy demonstrates excellent corrosion resistance, characterized by a low passivation current density, a large passivation range, and a high corrosion potential. Specifically, i pass is measured to be 4.59 x 10 -7 A/cm 2 , and E corr is -319 mV. Furthermore, the maximum Cr 2 O 3 oxide content in the alloy passivation film formed at 800 degrees C contributes to the passivation film stability.

The stress corrosion cracking mechanism of X80 carbon steel under the combined actions of chloride and bicarbonate ions in alternating wet-dry environment was investigated by performing slow strain rate tensile test and in-situ electrochemical detection during the SCC process under constant load. The results showed that the oxidation and reduction reaction cycle of iron oxide during wet-dry cycle would accelerate the corrosion process. The pitting under the corrosion product layer at high concentrations of chloride and bicarbonate was the origin of SCC under the action of stress concentration, which made steel display high SCC susceptibility.

The Co40Cr20Ni30Al5Ti5 multi-principal element alloy (MPEA) with heterogeneous grain structure (HGS) and nano L12 precipitates is successfully designed by cold rolling and proper heat treatment. The HGS alloy exhibits excellent corrosion resistance and passivation performance, originated from high-density grain boundaries in fine grains and abundant defects in deformed grains, which encourages surface to form a thicker and more efficient passive layer to inhibit the initial pitting corrosion. This finding indicates that the developed MPEA with HGS can possess an excellent combination of corrosion resistance and mechanical properties, providing highly positive factors for future applications.

High-entropy alloys (HEAs) are expected to possess various excellent properties due to their vast composition design space and unique core effects. Annealing treatments after cold rolling are widely discussed as an effective means to improve the overall performance of the alloy. Nevertheless, the effect of annealing treatments on the corrosion resistance of cold-deformed alloys is still somewhat controversial. Therefore, cold rolling and annealing at different temperatures are performed on the Co40Cr20Ni30Al5Ti5 high-entropy alloy to investigate the effect of annealing temperature on its corrosion behavior. The annealing temperature range covers all stages of the HEA recovery-recrystallization-grain growth (in 50 °C gradients). The experimental results show that the HEA recrystallization is fundamentally complete at 850 °C and fully austenitized at 1050 °C. The best corrosion resistance performance is observed at 850 °C, with the lowest corrosion current density (ipass) and the lightest pitting in full immersion experiments. In addition, excellent passivation properties, such as the lowest steady-state current density iss and highest passivation film growth rate, are achieved at 850 °C. Further analyses of the growth films also show that the passivation films formed at 850 °C are thicker and uniform, and additionally have the highest Cr2O3 content. Accordingly, the effects of annealing temperature on HEA corrosion resistance and passivation behavior are discussed. The superior corrosion resistance and passivation behavior at 850 °C are attributed to the coupling of grain size and passivation film composition. The current findings might guide the optimized design of future cold-deformed alloys for better corrosion resistance.

Electrochemical corrosion and stress corrosion cracking (SCC) behavior of X80 steel in the sulfurated marine environment at open circuit potential and −850 mVSCE are investigated. The results show that SCC is controlled by both anodic dissolution and hydrogen evolution, which is attributed to the HSO3− acceleration of the anodic and cathodic current density. Localized anodic dissolution leads to pits, which induce stress that promotes the initiation of stress corrosion cracks. Under a cathodic potential of −850 mVSCE, the effect of dissolution is limited, and SCC susceptibility increases because of the synergistic effect of the high HSO3−concentration and cathodic potential.

The stress corrosion cracking process of pipeline steel was modeled using cellular automata and finite element analysis, the initiation and propagation of the cracks were simulated. Before the initiation of cracks, the extent of pitting corrosion was revealed to be controlled by anodic reactions and mechanical factors, in which electrochemical corrosion played a leading role. The deposition of corrosion products created a diffusion barrier between the reactants participating in the corrosion process, limiting the rate of electrochemical reactions. During the crack propagation process, the mechanochemical effects caused by plastic deformation promoted anodic dissolution at the crack tip, driving crack propagation.

The present study attempts to improve corrosion resistant of high Co-Ni steel in similar to 1.0 wt% NaCl environment at 25 degrees C (room temperature) by different tempering times. Microstructures of specimens were characterized by X-ray diffraction (XRD), and scanning electron microscopy (SEM). The corrosion behavior was evaluated by polarization curve and electrochemical impedance spectroscopy. Firstly, the tempering time has a great influence on the morphology of martensite lath in high Co-Ni steel. Secondly, it was observed from the experimental data that a passivation/oxide layer with N-type semiconductor behavior was formed on all the samples studied in this paper. Increasing the tempering time can move the corrosion potential forward. Finally, tempering time of 16 h effectively improves the overall stability of the sample surface and reduces the corrosion tendency of the sample.

Ag15Cu85 binary alloy ribbon, as the precursor, was executed high-temperature oxidation at 650 degrees C and dealloying with different durations to fabricate nanoporous silver at different stages. The HER electrocatalytic performance of nanoporous silver at different stage was tested using open circuit potential (OCP), linear sweep voltammetry (LSV), and potential polarization curve. The results show that the nonporous silver electrode in the B1 stage has the best anti-toxic performance, Ecorr is -0.088V, and the icorr is 1.2x10(-7) A/cm(2); the nanoporous silver electrode in the A2 stage shows the lowest Tafel slope (45.8 mV dec(-1)); at a current density of 10 mA/cm(2), the hydrogen evolution overpotential of the nanoporous silver electrode in the B3 stage is 37.6 mV. From all those electrochemical tests, the nanoporous silver electrode in the B1 stage exhibited the best comprehensive HER performance.

To thoroughly explore the relationship between precipitation and corrosion in a precipitation-strengthened Al-4.47Zn-2.13Mg-1.20Cu (wt%) wrought alloy plate after a nonisothermal aging (NIA) treatment, specifically, a heating-aging treatment (HAT), electrochemical testing and transmission electron microscopy (TEM) were conducted in the present work. The H(5) process exhibited excellent corrosion resistance with a low corrosion current density (icorr) and a high corrosion potential (Ecorr) compared to those for the T6 treatment. After the HAT, the precipitates at the grain boundaries (GBs) gradually became intermittent with a narrow precipitate-free zone (PFZ), effectively preventing GBs precipitates from anodic dissolution. The HAT enabled the rapid diffusion and enrichment of Cu at the GBs and reduced the potential difference between the grain boundary and matrix, thereby decreasing the intergranular corrosion (IGC) susceptibility. Moreover, the time spent for a HAT can be decreased by approximately 70% in comparison with that for a T6 treatment. The current results indicate that NIAs could improve the mechanical properties and production efficiency with a decreased energy consumption.

The effect of a heating ageing treatment on the stress corrosion cracking (SCC) behaviour of an Al-4.47Zn-2.13Mg-1.20Cu (wt%) alloy in a simulated seawater solution in the presence and absence of sulfate-reducing bacteria (SRB) was studied by electrochemical techniques and stress corrosion tests. Different heating ageing treatments were applied to the samples. As the ageing rate decreased, the size of the precipitate in grain increased gradually, and the precipitate at the grain boundary displayed a progressively intermittent distribution with a narrow precipitate-free zone, which resisted stress corrosion. As the ageing rate decreased, the stress corrosion cracking susceptibility (I-scc) of alloy decreased, and the H10 aged samples in the sterile solution exhibited a minimum I-scc of 17.3%. In the SRB-inoculated solution, the impedance values of all samples were reduced, and the H10 process exhibited excellent stress corrosion cracking resistance with a low I-scc of 21.8%. The presence of SRB increased the SCC susceptibility due to the synergistic effect of sulfide produced by SRB metabolism, leading to hydrogen-induced cracking as the main type of stress corrosion of the alloy.