Abstract: Predeformation on tensile properties and microstructure of three Al-Cu-Li alloys, 1460, 2050 and 2A96 was investigated. The strength of the alloys is enhanced by the predeformation. Meanwhile, predeformation impacts the precipitation of T1 (Al2CuLi) and θ′(θ′′) (Al2Cu) phases. The precipitation (nucleation rate) of T1 is accelerated by the predeormation, and the effect is increased with the predeformation degree. While, effect on θ′(θ′′) precipitation is dependent on the alloy composition feature. In the 2A96 alloy with a medium Cu/Li ratio, it is decelerated by the predeformation. In the 2050 alloy with high Cu/Li ratio and 1460 alloy with low Cu/Li ratio but subjected to two-step aging at 130°C and 160°C, the θ′(θ′′) precipitation is accelerated at lower predeformation but decelerated at higher predeformation.
Abstract: A precipitation hardenable Al-Cu-Mg alloy was cryorolled with liquid nitrogen followed solution treatment and then aged at 170 ̊C for different time. The microstructure was characterized by optical microscopy (OM) and transmission electron microscopy (TEM). Hardness and tensile strength were also tested. The dislocation loops in the cryorolled alloy are more than the room temperature rolled alloy. Meanwhile the hardness, yield strength and tensile strength are larger than the room temperature rolled alloy.
Abstract: In this paper, weak water cooling technology by wiper is introduced for the casting of 520×1650 mm 7A55 alloy slabs. By analyzing from experiment comprehensively, it indicates that the position of wiper will exert big influence on slab quality. Under the conditions of the experiment, if wiper height is below the bottom of sump, there will be more than 70% possibility for slab to have cracks. If it is excessively higher than 80 mm, the top of the sump, porosity will incur and macro-segregation will be enlarged. The experiment determines the correct height of wiper.
Abstract: The strain field of η′ phase in an aged 7000 series aluminum alloy has been investigated using a combination of high resolution transmission electron microscopy (HRTEM) and geometric phase analysis (GPA) technique in this paper, and strain components εxx, εyy were mapped, respectively. The results showed that the strain is mainly generated near the matrix/η′ phase interface and gradually decreases with distance increasing away from the interface. There were convergence and divergence regions of the strain within the η′ phase, and maximum strain occurred in the position where about 0.25 nm far from the interface, value of the maximum strains was about 2.54%.
Abstract: The influence of larger pre-strains, than are currently used in industry, has been investigated on the ageing behaviour of the Al-Cu-Li alloy 2195 - in the context of producing near-net-shape, taper-rolled, thickness-tailored, plates for aerospace applications. FE modelling and simulations have demonstrated it is viable to stretch plates with rolled tapers of up to 1:1.6 in thickness. Increasing the pre-strain level at the thin end of the plate, up to 15%, resulted in a continued increase in microstructure refinement and yield strength, which rose to ~ 670 MPa without an unacceptable loss of ductility. It is shown that, even with such high pre-strains, a relatively low level of recovery occurs after artificial ageing and increasing the pre-strain is predicted to result in a reduction in strengthening from the T1 phase, due to precipitate refinement, in favour of a higher contribution from strain hardening.
Abstract: Erbium is an effective micro-alloying element in aluminum alloys and has been investigated intensively. Similar with the addition of Sc in aluminum alloys, nanosized L12-ordered Al3Er precipitates were formed coherently with the matrix in Er-containing micro-alloying aluminum alloys. Further, in the case of the addition of both Er and Zr, core-shell-structured Al3(ZrxEr1−x) precipitates, instead of Al3Er, were observed in a fine dispersion. Those thermally-stable precipitates can refine the grain size, minimize the segregation, homogenize the microstructure, enhance the strength, hinder the recrystallization, and thus improve the comprehensive performance of the aluminum alloys. This paper presents the effect of Er on the microstructure, mechanical properties and thermal stability of aluminum alloys. The research of some typical commercial aluminum alloys containing Er, is also reviewed here.
Abstract: Recent advances in the fundamental research on the alloy development, microstructure control, property evaluation for aluminum alloys and industrial technologies in Japan is introduced. The production status of aluminum in Japan is also introduced together with the activities in the aluminum organization and academic society. Some of the recent research topics, nanohetero structure and nanocluster controlling, are presented.
Abstract: This work extracted the iron-rich phases in aluminium alloy containing the iron of 0.3%, 0.6%, 1%, 0.6%, 2% and 5% respectively, and studied the morphology and the structure of the iron-rich phases by using electrolytic extraction technology. The results showed that the iron-rich phase in aluminium alloy is a large number of alpha - Al3Fe and a small amount of lambda - Al13Fe4; the rich iron phases are distributed in aluminum alloy substrate in three-dimensional space, and its metallographic appearances in different sections present sheet, plate and needle-like structure. High resolution electron microscopy shows that lambda - Al13Fe4 and alpha - Al3Fe are tetrahedral structure, and when iron content is 0.3% - 1%, the iron-rich phase transition of lambda - Al13Fe4 to alpha - Al3Fe is influenced by iron content, and alpha - Al3Fe lattice constants a and c are bigger than that of standard value under 0.3% iron content, and alpha - Al3Fe lattice constant a changes little with the increase of iron content, and the lattice constant c becomes larger along with the increase of iron content, and when the iron content is up to 1%, the lattice constant a and c are gradually stabilized; lambda - Al13Fe4 lattice constant a and c are constant.
Abstract: In this study we aim at combining the results from transmission electron microscopy (TEM) and atom probe tomography (APT) to study the early stages of phase decomposition in the age hardening alloy AA 6016. Samples are subjected to different periods of natural ageing or artificial pre-ageing at elevated temperature in order to produce different types of clusters and early stages of precipitation before age hardening commences. APT is utilized to detect clusters and identify their compositions, whereas TEM is applied to analyse and quantify number density and sizes of the particles during artificial ageing at 185°C. It is shown that the two techniques, TEM and APT, are complementary and a combined approach yields more detailed insight into the early stages of phase decomposition in age hardening 6xxx series alloys than possible by the sole use of either technique individually.
Abstract: An aluminum matrix composite reinforced by TiC and Al2O3 particles was synthesized using TiO2, C, and Al powder by the in-situ reaction. The effects of deformation parameters on the microstructure of the TiC-Al2O3/Al composite were investigated using XRD, SEM and TEM. The result shows that the strain rate and deformation temperature influence the size, styles, and distribution of the second phase. Reinforcements are dispersed in a distribution with increasing deformation temperature and strain rate. However, broken Al3Ti exhibits redissolution phenomenon. The new precipitated Al3Ti phase will precipitate from the strain-induced solid solution when the total strain increases to a certain degree at a high deformation temperature.