Quantitative study of nanoscale precipitates in Al–Zn–Mg–Cu alloys with different chemical compositions

Evolution of surface characteristics of two industrial 7xxx aluminium alloys exposed to humidity at moderate temperature

“…In the present study, the local chemistry of grain boundaries has not been analysed since industrial Al‐Zn‐Mg‐Cu alloys develop complex microstructures. However, the grain boundary precipitates in Alloy B are expected to be mainly MgZn 2 because the increased zinc content as well as the reduced magnesium and copper content of Alloy B results in a higher volume fraction and number density of hardening precipitates . Furthermore, the very low content of impurities (Si, Fe) reduces the formation of coarse intermetallics .…”

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

“…Compared to those in the powders, the continuous precipitates along sub-grain boundaries were broken up into segments after sintering and natural aging. The final sintering and dwell temperature (450 o C) was close to the solution treatment temperature (460-480 o C) [34,35], therefore, some precipitates redissolved into metal matrix during sintering. While, during the following cooling and natural aging period, the intermetallic particles could reprecipitate and grow big, showing higher density and more separated feature.…”

“…Corrosion behavior closely relates to microstructure and microchemistry of metal such as grain size, residual stress, the composition and structure of grain boundary precipitates (GBP) and PFZ [3,11,35,36,[60][61][62][63][64][65]. In fact an obvious microstructure difference in coarse and fine grains is the difference in size and population density of intermetallic particles.…”

Effects of germanium on quench sensitivity in Al–Zn–Mg–Zr alloy

“…This meant the addition of Ge to Al-Zn-Mg-Zr alloys suppressed the formation of coarse particles during cooling from elevated temperature. Based on the strengthening mechanism [18,19], the formation of large η particles during quenching depleted the matrix solutes available for aging, leading to a considerably decrease in hardening capability of alloys [20,21]. Therefore, the quantity of coarse particles was responsible for quench sensitivity.…”