Study of aging and electrochemical behaviour of AlLiCuMg alloys

The influence of creep aging at varied stresses on the localized corrosion behavior of AA2060 has been studied in this paper. Samples were subjected to stress free aging (SFA) and creep aging (CA) under two stress levels, after which tensile tests and intergranular corrosion (IGC) tests were carried out. The corrosion morphology and depth were examined using optical microscope. Compared with SFA, CA can enhance the mechanical properties and increase the IGC resistance of Al–Cu–Li alloy but high‐stress CA would intensify the intragranular corrosion penetration in the first 25 hr of aging time. The microstructure observation results show that dislocations introduced by CA provide favorable nucleation sites for T1 precipitates in the grain and impede the growth of T1 precipitates at grain boundary. Therefore, the potential difference between the grain interior and grain boundary can be reduced compared to that for the SFA. The mechanism by which CA affects the corrosion resistance of Al–Cu–Li alloys, as is essential to understand and optimize the creep aging process, has been proposed by considering the effect of creep‐deformation‐induced dislocations.

Section: Resultsmentioning

confidence: 99%

The effect of creep aging on localized corrosion resistance of AA2060 alloy

Wang

Zhan

Liu

et al. 2019

“…It is observed from Figure that when the potentials are shifted to the anodic domain, the anodic current densities increase rapidly. This potential is considered to be the oxide breakdown ( E bd ) or pitting potential ( E pit ) that leads to localized corrosion . The initiation of localized corrosion leads to a rapid increase in the anode current density …”

Section: Resultsmentioning

confidence: 99%

Electrochemical assessment of laser heat treatment of an Al–Zn–Mg–Cu alloy

Wang

Liu

et al. 2019

The effect of laser heat treatment on the corrosion properties of the 7075 aluminum alloy was studied electrochemically. Laser retrogression and re‐aging (LRRA) is proposed to replace the retrogression treatment of retrogression and re‐aging. Transmission electron microscopy was used to analyze the microstructure of the alloy. The corrosion of the alloy treated using different LRRA parameters was analyzed by scanning electron microscopy. Using the polarization and electrochemical impedance spectroscopy measurements, it was concluded that the best corrosion resistance was obtained by the alloy treated at 2 mm/s with a laser power of 650 W. The spacing between the precipitate‐free zone and grain boundary precipitates increased. It is proved that the laser process can effectively improve the corrosion resistance of the 7075 alloy.

“…Al–Cu–Li–Zr–Sc alloy is classified as a heat‐treated and strengthened aluminum alloy . Different aging processes will affect the distribution of precipitated phases, which may affect the corrosion performance of an alloy; an in‐depth study of the effects of aging on the corrosion performance of Al–Cu–Li–Zr–Sc alloy is, therefore, warranted …”

Section: Introductionmentioning

confidence: 99%

Effect of different aging processes on the corrosion behavior of new Al–Cu–Li–Zr–Sc alloys

Peng

Pan

Cai

et al. 2019

The intergranular corrosion and exfoliation corrosion behaviors of Al-Cu-Li-Zr-Sc alloys under different aging effects, such as single-stage aging, strain aging, and double-stage aging, were studied. Among the three aging treatments, single-stage aging resulted in the best resistance to corrosion, followed by double-stage aging; strain aging resulted in the worst corrosion resistance. A 3.5% precooling strain could increase the dislocation density, which promoted the precipitation of corrosion-prone T 1 phase and increased the corrosion driving force of the alloy. Double-stage aging made the precipitated T 1 phases finer and more uniform and reduced the number of equilibrium phases at grain boundaries, thus improving the corrosion properties of the alloy. The corrosion susceptibility of the alloy was attributed to the T 1 phase and precipitate-free zone (PFZ), and the underlying corrosion mechanism was revealed as preferential dissolution of the equilibrium phase at grain boundaries and its surrounding distortion zone, followed by expansion of the PFZ along the grain boundaries, resulting in the development of corrosion from the grain boundaries to the intragranular regions. K E Y W O R D SAl-Cu-Li alloys, corrosion, double-stage aging, single-stage aging, strain aging