Lizhen Yan

In this work, the effects of the Cu/Li ratio on the mechanical properties and corrosion behavior of Sc-containing Al-Cu-Li alloys were systematically investigated by utilizing age-hardening behavior, tensile property, corrosion behavior, and electrochemical behavior, complemented by microstructural characterization through EBSD and TEM. The results...

The influence of Cu content (3.10, 3.50, and 3.80 wt.%) on the precipitation behavior and mechanical properties of Al-Cu-Li alloys under two aging conditions (direct aging at 175 °C vs. 3.5% pre-stretching followed by aging at 155 °C) was systematically investigated. The alloys were characterized using hardness testing, tensile property evaluation,...

The number of fasteners used in aircraft is vast, reaching millions. Aluminum alloy wire for fasteners has become a focus of research. In this study, the Al-Zn-Mg-Cu alloy wire was prepared by hot rolling and extruding methods. A comparative analysis of microstructure and mechanical properties was examined. Results indicated that the hot rolling te...

Solid-state additive manufacturing (SSAM) is an emerging technology that offers a unique approach by avoiding the melting and solidification of metals during the fabricating process. As a result, it eliminates common solidification related defects like porosity and cracking. This method is characterized by low residual stress, low distortion, and t...

The 7085 aluminum alloy with a low Cu content is an important lightweight structural material in the aerospace field due to its advantages of low density, high specific strength, and high hardenability. However, like other high-strength Al-Zn-Mg-Cu alloys, this alloy is susceptible to stress corrosion cracking (SCC). Additionally, the lower Cu cont...

A multilayered build was fabricated by friction stir additive manufacturing (FSAM) with different parameters, using 4-mm thick 7A04-T6 aluminum alloy sheets in this study. The parameters effect on the microstructure and mechanical properties of the builds were investigated combined scanning electron microscopy (SEM), transmission electron microscop...

In the research, the microstructures of large-scale 2324 aluminum alloy thick plates obtained through two different hot rolling processes are investigated by using Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDS), and Electron Backscatter Diffraction (EBSD). Additionally, the tensile properties of the plates are evaluated at...

In crossover Al-Mg-Zn alloys, the T-phase (Mg 32 (Al, Zn) 49 ) is crucial for reinforcement. The critical nucleation size of the precipitated T-phase is notably reduced by Cu addition, as well as the activation energy. There is a lack of theoretical research on the influence of Cu elements on the stability of T-phases and mechanical properties. In...

In 6000-series Al-Mg-Si alloys, Zn is commonly added to enhance the aging response for improved properties. However, the segregation of Zn to interfaces and its interaction mechanisms with strengthening phases remain unclear. Combining experiments and theoretical calculations, we systematically investigated Zn segregation behavior at the β″/Al inte...

Al–Li alloys, characterized by their lightweight and high strength, are essential structural materials in aerospace industry. Unraveling the atomic mechanisms that enhance the modulus of Al–Li alloys is key to developing the next-generation alloys. Utilizing first-principles methods, we systematically explored the influence of alloying elements on...

In this work, the evolution of mechanical properties of binary Al–Li alloys with four approximately equal gradient Li contents (0.91–3.98 wt.%) under aging conditions is thoroughly investigated. The alloys undergo aging treatments at 175 °C for x hours (x = 0–120 h), and the peak-aged times of the four alloys are 6 h, 12 h, 48 h and 48 h, respectiv...

In the present study, the effects of varying heating and cooling rates during the solution treatment process on the microstructure and properties of AA7050 alloy wires were investigated using tensile tests, metallographic microscopy, electron backscattered diffraction, and transmission electron microscopy. It was found that the recrystallized grain...

In the current study, the evolution of S(Al2CuMg) phase in a commercial Al-Zn-Mg-Cu alloy during homogenization, deformation and solution treatments was investigated and the effect of residual S(Al2CuMg) phase on mechanical properties in finished plates was revealed. The results showed that S(Al2CuMg) phase formed during solidifications and existed...

The precipitation of secondary Al 3 (Sc, Zr) particles in Al-Mg-Zn-Sc-Zr alloy during the two-stage homogenization has been studied by OM, SEM, and TEM. The results indicated that Al 3 (Sc, Zr) particles grew gradually with the first-stage homogenization temperature ranging from 380°C to 440°C. The first-stage homogenization temperature greatly aff...

This work investigated effect of Cu addition on fatigue crack growth rate and fatigue fracture morphology of Al-1.2Mg-1.2Si alloy by fatigue test machine and Scanning Electron Microscope. It revealed that effect of Cu on the fatigue crack growth rate of these alloys was related to Cu content. When the Cu content was 0.18, there did no significant i...

In this study, the effects of Cu addition on artificial age hardening behavior and mechanical properties of Al-1.2Mg-1.2Si-(xCu) alloy was investigated quantitatively and qualitatively by Vickers hardness, tensile test, and transmission electron microscope. The results indicated that Cu addition enhanced the aging response of the alloy at 175 °C. W...

The effect of trace Sc and Zr on grain refinement of Al-5.0Mg-3.0Zn as-cast alloy was investigated by optical microscopy and scanning electron microscopy with EDS. The results indicated that the critical quantities of Sc and Zr for Al-Mg-Zn alloy to produce a significant refining effect were determined and the total mass fraction of Sc and Zr was n...

In present study, grain characteristics with sizes within 10–30 μm were fabricated from a same Al–Zn–Mg–Cu alloy, FCP behaviors of the alloys with small grain (SG alloy), medium grain (MG alloy) and large grain (LG alloy) were investigated and related fatigue fracture morphology was analyzed. With the enhancement of stress intensity factor range (Δ...

Twin-roll casting (TRC), as a near-net-shape technology, is employed to fabricate age-hardened Al-Mg-Si alloy. Compared with conventional direct chill (DC) casting, the TRC method is much more economical and efficient. In this work, the microstructure, precipitates behavior, and mechanical properties of age-hardened Al-Mg-Si alloy sheet fabricated...

During the immersion quenching process, severe temperature changes and significant temperature differences between the core and superficial area can give rise to high residual stresses within the aluminum alloy thick plate to cause subsequent machining distortion of the thin-walled part. Reducing the residual stress within the thick plate can effec...

Solution heat treatment combined with a rapid quenching operation, which can effectively suppress the decomposition of the supersaturated solid solution in the matrix, is a vital process step for producing large precipitation-hardenable aluminum alloy thick plates with desired properties. However, large thermal gradients that result from the non-un...

The correlations between the structures, fracture behavior and dynamic shear property were investigated for 7050 to 7N01 layer of 7N01/7A01/7050 multilayer plate with different thickness ratio fabricated by hot rolling bonding. is The results showed that when thickness ratio of 7050 to 7N01 layer was 1 and 7050 layer was backplane, the absorbed ene...

Effect of different cold rolling deformations before intermediate annealing on the microstructure and forming properties of 6A16 aluminum alloy sheet during subsequent processing was investigated by means of EBSD and mechanical properties tests.The results show that with the increase of cold deformation before intermediate annealing, the size of th...

Secondary cracks were frequently reported in fatigue failure of aviation aluminum alloy. In present study, scanning electron microscope observation of fracture morphology was carried out on an Al-Zn-Mg-Cu alloy extrusion plate with high zinc content. Secondary cracks penetrated continuous dimples formed via a chain of discontinuously distributed Fe...

The plasticity, fracture toughness and stress corrosion cracking resistance of a high-alloying Al-Zn-Mg-Cu alloy with various recrystallization degrees introduced by solution treatment were investigated. The results exhibited that the elongation increased from 14.73% to 16.38% with the deepening of recrystallization degree from 8.80% to 20.20%, as...

Based on the ABAQUS / Explicit finite element method, the forming force changing trend of deep drawing test for 6A16 aluminum alloy plate after pre-aging and storage at room temperature for one month was simulated under friction coefficient ranging from 0 to 0.22. The lubricants selected for the tests were mechanical oil, butter and dry film lubric...

Precipitation characteristics influencing fatigue crack propagation contained matrix precipitate, grain boundary precipitate and precipitate free zone for Al–Zn–Mg–Cu alloys. Over-aging treatment could effectively regulate precipitation and then to be able to change fatigue crack propagation behavior compared with the peak aging state. In the curre...

This study investigates the effect of Zn addition two-step behaviour in an Al–Mg–Si–Cu alloy. During pre-aging at 100°C for 3 h, the Zn can partition into clusters because of the strong Zn–Mg interaction, prompting the formation of clusters. During subsequent artificial aging at 180°C for up to 240 min (peak hardness condition), the Zn does not sig...

A cellular automata (CA) model has been developed to predict and control the microstructure evolution during hot deformation on 7085 aluminum alloy. The initial microstructure and thermal-mechanical parameters were used as the input data of the CA model. To link microstructure evolution with macroscopic flow stress, dislocation density was set as a...

The 6005A-T5 aluminum alloy welded joints were prepared by use of friction stir welding (FSW) and metal inert gas welding (MIG). The difference in microstructure and mechanical properties of the two types of welded joints were investigated by optical microscopy (OM), scanning electron microscopy (SEM), transmission electron microscope (TEM), Vicker...

6xxx series aluminum alloy is one of the ideal automotive lighting materials for its high strength, excellent formability, good corrosion resistance, and weldability. In this paper, the effect of pre-aging technology on microstructure and properties of 6111 aluminum alloy was investigated by using TEM, tensile, and Erichsen test. The results showed...

The microstructural evolution of an Al–Zn–Mg–Cu aluminum alloy during an optimized two-step homogenization treatment was investigated by optical microscopy (OM) and scanning electron microscopy (SEM) equipped with energy-dispersive spectrometer (EDS) and differential scanning calorimetry (DSC). It mainly focused on secondary phase transformation an...

In this paper, Al–11Zn–3Mg–2Cu–0.2Zr alloy was prepared by spray-forming, and then it was treated by defect reduction, hot worked and heat treatment. Microstructure and mechanical properties of the aluminum alloy were researched during the whole processing by metallographic microscope, scanning electron microscope (SEM), and tensile test. Average g...

The microstructural evolution and phase transformation of cast Al–1.5Mg–0.6Si–3Li (mass %) alloy during homogenization were investigated. The results show that severe dendritic segregation exists in the as-cast ingot. Mg and Si elements segregate at grain boundaries to form intermetallic Mg2Si phase. In addition, there also exists Li-containing pha...

The flow behavior of a high-alloying Al–Zn–Mg–Cu alloy was studied by compression tests with the temperature range of 300–440 °C and the strain rates range of 0.001–1 s⁻¹, and the corresponding microstructural evolution was observed. Results show flow stress curves exhibit the peak value at a critical strain, and the peak stress decreases with incr...

This study investigates the clustering behavior and its correlation with the change in hardness during natural aging (NA) after pre-aging (PA) at 80 °C for 15 min in Al–Mg–Si–Cu alloys with and without Zn addition. The results show that NA after PA causes the growth of clusters in the Zn-free and Zn-added alloys, which is related to the partitionin...

The effects of Zn on the age hardening behavior and corresponding microstructure of an Al-0.9Mg-0.8Si-0.2Cu (wt%) alloy were investigated by hardness testing, transmission electron microscopy (TEM) and three-dimensional atom probe (3DAP). During aging for up to 8 h at 170 °C (peak hardness condition), the addition of Zn does not alter the precipita...

Homogenization heat treatment on an Al–0.92Mg–0.78Si–0.60Zn–0.20Cu–0.12Zr alloy was investigated by OM (optical microscopy), DSC (differential scanning calorimetry), energy dispersive X-ray diffractometry (EDX), and SEM (scanning electron microscopy) in the present work. The results indicated that with homogenization temperature increasing, the gra...

Cellular Automata (CA) method can be used to simulate the microstructure evolution. The parameters of the CA model and thermal deformation parameters are input to the CA model as important data. The hot deformation behavior was studied by means of a hot simulating test on Geleeble-1500 experiment machine. The range of thermal deformation temperatur...

The microstructure and properties of spray-formed Si–30Al alloy was studied in this paper, which was used for electronic packaging. Hot isostatic pressing was used to compact the ingot, and then electroplating and brazing was carried out. The results showed that, (1) the Si–30Al alloy comprised α-Al phase, pseudo eutectic phase and primary silicon...

Isothermal compression tests of the Al–9.4Zn–1.9Mg–2.0Cu alloy were carried out at the temperature ranging from 300 to 460 °C and the strain rate from 0.001 to 10 s⁻¹, and the deformation degree was 70%. Flow stress curves show that the flow stress decreases with the increasing deformation temperature and the decreasing strain rate. The measured fl...

The porous defects classification in spray-formed Al–Zn–Mg–Cu alloy was investigated in this paper during spray forming, hot isostatic pressing (HIP) and homogenization. Metallographic microscopy and scanning electron microscopy (SEM) were used to study the microstructure and porous defects. The results showed that, there were four kinds of porous...

Homogenization heat treatment on an Al–0.92Mg–0.78Si–0.60Zn–0.20Cu–0.12Zr alloy was investigated by OM (optical microscopy), DSC (differential scanning calorimetry), energy dispersive X-ray diffractometry (EDX), and SEM (scanning electron microscopy) in the present work. The results indicated that with homogenization temperature increasing, the gra...

The accuracy of different residual stress measurement methods has always been the research focus from the beginning of research on residual stress. In this study, both conventional and newly-developed methods were applied to measure the residual stress in as-quenched 7055 aluminum plate. Methods such as hole drilling, X-ray diffraction based on sin...

Aluminum drill pipes have low density, high specific strength and good stress corrosion resistance, possessing a huge application potential in the oil drilling. The 1953 alloy belongs to the Al–Zn–Mg–Cu alloy, and it is one of the most promising aluminum alloy materials for petroleum drill pipe. In this paper, the 1953 aluminum alloy were studied b...

In the present work, the influence of various retrogression treatments on hardness, electrical conductivity and mechanical properties of a high Zn-containing Al–Zn–Mg–Cu alloy is investigated and several retrogression regimes subjected to a same strength level are proposed. The precipitates are qualitatively investigated by means of transmission el...

A high Zn-containing Al-Zn-Mg-Cu alloy was researched due to excellent overall performances. The hardness, electrical conductivity and mechanical properties were investigated and detailed aging parameters subjected to T6, T79, T74 and T73 were proposed. The matrix precipitates of various aging tempers were investigated by transmission electron micr...

Property evolution in a high Zn-containing Al–9.78Zn–2.02Mg–1.76Cu alloy treated at 120°C, with the microstructure subjected to under-aging (UA), peak-aging (PA) and over-aging (OA), is investigated. Precipitate size distributions and distances between neighbouring precipitates are determined. Results indicate that a certain time is required to rea...

Pre-aging on early-age behavior and bake hardening response of an Al-0.90Mg-0.80Si-0.64Zn alloy was investigated by differential scanning calorimetry (DSC), high resolution transmission electron microscopy (HRTEM), 3-dimensional atom probe (3DAP), Erichsen test and tensile test. The results indicated that pre-aged alloy exhibited excellent formabil...

The effect of solution heat treatment (SHT) on mechanical properties, microstructure and surface quality of Al-1.2Mg-0.6Si-0.2Cu-0.6Zn alloy was investigated by tensile test, Erichsen test, surface topography, scanning electron microscope (SEM) and electron back-scattered diffraction (EBSD). The results indicate that with the increase in SHT temper...

The hot deformation process on grain size and surface quality after pre-aging of 6016 aluminium alloy were investigated by mechanical properties, surface topography and electron backscatter diffraction (EBSD) technique. The results indicated that after different hot rolling processes, the alloy sheets achieved similar mechanical properties and form...

In the present work, an Al–0.66Mg–0.85Si–0.2Cu alloy with Zn addition was investigated by electron back scattering diffraction (EBSD), high resolution electron microscopy (HREM), tensile and Erichsen tests. The mechanical properties of the alloy after pre-aging met the standards of sheet forming. After paint baking, the yield strength of the alloy...

The microstructural evolution of Al–0.66Mg–0.85Si alloy was investigated by optical microscopy (OM), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and differential scanning calorimetry (DSC). The as-cast microstructure is typical dendritical structure, consisting of α(Al), Al(FeMn)Si, Mg2Si, AlCuMgSi and Si phases. The...

To meet the stringent requirements of ultra-thick section products for aerospace applications, an Al-7.6Zn-1.8Mg-1.4Cu-0.12Zr alloy with good performance was developed. The behavior of the alloy during hot deformation was studied by isothermal compression in the temperature range from 250°C to 450°C and strain rate from 0.001 s-1 to 10 s-1 on Gleeb...

To meet the stringent requirements of ultra-thick section products for aerospace applications, an Al-7.6Zn-1.8Mg-1.4Cu-0.12Zr alloy with good performance was developed. The behavior of the alloy during hot deformation was studied by isothermal compression in the temperature range from 250°C to 450°C and strain rate from 0.001 s⁻¹ to 10 s⁻¹ on Gleeb...