The microstructure of 5182 alloys, standard and modified by Zr, before/after homogenizing heat treatment were investigated by optical microscope (OM), scanning electron microscope (SEM) with energy dispersive spectroscopy (EDS) and transmission electron microscope (TEM). The microstructures on optimum condition for homogenizing heat treatment and the effect of Zr were discussed. It is found that the intermetallic compounds formed on the grain boundaries are less in Zr modified 5182 than 5182 alloys for the as-cast structure. After the two alloys homogenized at 475 for 24h, the dendritic structure disappear and intermetallic compounds become discontinuous, Al2Mg3 phases are decomposed, and there are some precipitates of Al6(Mn,Fe) and Al6Mn in the grain interior. In addition, precipitates of Al3Zr distributed in the matrix of Zr modified 5182 alloys.

No abstract

In this paper, the Al-8.5Fe-1.3V-1.7Si alloy was fabricated by spray forming and forging processes. The microstructure and mechanical properties of the alloy were investigated by means of metallographic, scanning electron microscope and tensile test. The results indicate that spray formed Al-8.5Fe-1.3V-1.7Si alloy after pressing plus can forging processes displays excellent microstructure and characterization.

In this study, the effect of various aging treatment (T6 and T7 treatment) on the mechanical properties, electrical conductivity and the microstructure of an Al-7.5Zn-1.3Mg-1.4Cu-0.12Zr alloy has been investigated. The results show that with elevating the aging treatment temperatures, the aging response rate is greatly accelerated. When T6 temper is performed at 140°C for 12h, as compared to peak aging for 24h at 120°C, the UTS and the corresponding Elongation values keep the same level, whereas the TYS and the electrical conductivity obviously increase by 5% and 9%, which is up to 560 MPa and 22.6 MS/m, respectively. And there are clear PFZs along the grain boundary and slightly coarser precipitates inside the grain. GPI zones, GPII zones and η' phases are major precipitates for the alloy under T6 condition. When T7 temper is performed on the alloy, the main precipitates are GPII zones, η′ and η phases. The coarser precipitates inside the grain and discontinuous grain boundary precipitates are favorable to electrical conductivity, which decrease the strength of 5~17% compared to T6 treatment. After T76 treatment (i.e., 110°C/6 h + 160°C/6 h), the UTS, TYS, Elongation and electrical conductivity values were 540 MPa, 510 MPa, 16.7% and 23.5 MS/m, respectively.

In this present work, the microstructure and properties of an Al-7.5Zn-1.5Mg-1.4Cu-0.12Zr alloy forging in T7452 condition has been investigated by means of OM, TEM and EBSD analysis and varied properties test. The results indicate that there are obvious differences in grain morphology, precipitation characteristics and recrystallization degree along the thickness direction of the forging. The strength of the alloy forging is stable and varies less than 10% along the thickness direction. The alloy forging in the T7452 condition shows high strength, high toughness and good corrosion resistance, with the UTS, TYS, elongation and electrical conductivity values being 500~530 MPa, 460~500 MPa, 7.0~15.0% and 23.9~24.2 MS/m, respectively, and the fracture toughness in L-T, T-L and S-L direction being 33.5~39.5, 25.5~27.0, 23.0~24.5 MPa.m1/2, respectively, and the EXCO rating being EA.