The characteristic parameters of electrochemical noise (EN) spectra were used to study the corrosion process of aluminum alloy in distilled water with or without chlorate (Cl-).The experimental results showed that the parameters obtained from the time-domain spectra analysis were not consistent with the parameters obtained from the frequency-domain analysis. This paper attempted to explain the phenomenon by the time-domain noise spectra, the corrosion characteristic of aluminum alloy, the source of noise transient, and the types of the pitting corrosion of aluminum alloy.
The electrochemical properties of Al-Zn-Ga-In-(Pb/Bi) anode alloy are studied by electrochemical test, including constant current test, polarization curve test, AC impedance test. Metallographic microscope is used to observe the microstructure of the alloy . energy spectrum technical is used to analyze the second phase elements. The results showed that the adding of element Pb or Bi both can attain more negative open-circuit potential; the adding of Bi makes the working potential shift positively, and reduces the current efficiency; 2% Pb content can attain more negative working potential, and current efficiency are increased slightly; the series anode the morphology of dissolution relatively uniformly in 3% NaCl solution; anodic polarization are all relatively smaller than cathodic polarization, and they have good anodic polarization properties. The overall electrochemical properties of Al-3Zn-0.015Ga-0.025In-2Pb alloy are the best in these five aluminum alloy anode.
Soften behavior of 7050 aluminum alloy was investigated by high temperature compression tests conducted at 460 °C with different strain rates of 0.1, 1, 10 and 100 s-1. The results show that all the volume fractions of recrystallized grain and substructed grain of the 7050 aluminum alloy deformed at 460 °C with different strain rates are higher than 35% and 20%, respectively. Dynamic recovery and dynamic recrystallization are primary soften mechanism of the 7050 aluminum alloy deformation at 460 °C, which is not sensitive to strain rate. The recryatallization nucleation mechanisms of the 7050 aluminum alloy deformed at 460 °C include in grain boundary arch, subgrain growth and subgrain merging.
Plastic anisotropy of the as-rolled 7050 aluminum alloy plate with T7451 temper was investigated by tensile tests, OM, SEM and TEM. The results show that the as-rolled 7050 aluminum alloy plate shows plastic anisotropy. The values of the as-rolled 7050 aluminum alloy plate deformed along ST, LT and RD are 7.178%, 10.69% and 12.877%, respectively. The as-rolled 7050 aluminum plate can be considered as a materials with two phases. Microstructure, especially grain shape and precipitate configuration, is the main source of plastic anisotropy of the as-rolled 7050 aluminum alloy plate with T7451 temper.
Five Al-Bi-Sn-In-Ga alloys with different Bi content were designed and prepared. Their electrochemical properties in 3% sodium chloride solution, the distribution of alloying elements and surface morphologies were studied by means of loss of weight method, polarization curve, electrochemical impedance spectroscopy (EIS) and energy spectrum analysis. The results indicate that, a good deal Bi and other alloying elements form new phases which exist in grain boundaries in the form of dot or granule, and Bi rich regions are prone to become the inductive points of pitting corrosion. Moreover, there is a certain linear relation between Bi content and the self corrosion rate.
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