Influence of repetitious-RRA treatment on the strength and SCC resistance of Al–Zn–Mg–Cu alloy

Enhanced fatigue crack propagation resistance in a superhigh strength Al–Zn–Mg–Cu alloy by modifying RRA treatment

“…It was reported that the microstructural parameters such as grain orientation, grain size, grain boundary and precipitates affected the fatigue crack propagation behavior, especially in near-threshold regime [10,11,14]. In view of the same solution treatment and the low aging temperature in both samples, the degree of recrystallization in two samples should be roughly equivalent.…”

“…zones and fine η' particles are dissolved in matrix, and isolated grain boundary particles are formed, while in the re-aging stage, η' particles are re-precipitated [7,8]. This characteristic microstructure leads to a good combination of the mechanical performance and SCC resistance [9,10,11].…”

Pitting corrosion of naturally aged AA 7075 aluminum alloys with bimodal grain size

“…A concurrent decrease in zinc, magnesium content and increase in copper content would make η-phase less anodic. Therefore, the increase in copper content shifts the potential of η-phase towards noble direction, while the presence of zinc and magnesium would decrease the potential of η-phase and make it more active [9,10,40,43,66,76,[81][82][83][84][85][86][87]. In this study, the η-phase in coarse grains has bigger size and higher content of magnesium, zinc and copper compared to that in fine grains.…”

“…In the artificial aging condition, with a relatively high temperature (usually higher than 120 o C), the copper can substitutes the zinc sites in η-phase, therefore the copper content will increase with prolonging aging time. This is the main reason why over-aged alloys usually have a higher copper content in η-phase and thus a better corrosion resistance than peak-aged one [9,10,40,43,66,84,[81][82][83][84][85][86][87]. In this work, the natural aging was performed near room temperature (30-35 o C), the copper diffusion should be very slow and restricted.…”

Effect of retrogression and re-ageing heat treatment on microstructure and microhardness of aluminium 7010 alloy

“…They have Zn, Mg and Cu as alloying elements, these alloys are precipitation hardened alloys, with general precipitation sequence in the order of supersaturated solid solution (SSSS) GP zones ή η (MgZn2) [2]. The ή precipitates formed during the precipitation sequence is the metastable precipitate of MgZn2, which is semicoherent with the matrix and is the major strengthening phase of the alloy.…”