According to the maximum solid solubility of Zn， Mg， Cu in aluminum and their precipitation strengthening phases， Al-12Zn-2Mg-0.5Cu-0.3Sc high strength aluminum alloy is designed. The billet of this alloy is hot rolled followed by clod rolling and heat treatment to explore the optimal heat treatment process for aluminum alloy with high solid solubility to obtain good tensile properties. Optical microscopy （OM）， X-ray diffractometry （XRD） ， and scanning electron microscopy （SEM） are used to observe and analyze the microstructure of the alloy under different heat treatment conditions， and universal tensile testing machine is used to test the tensile properties of the alloy at room temperature. The results show that after solution treatment of 470 ℃/1 h， the microstructure of the cold-rolled alloy is incomplete recrystallized with elongated grains along the rolling direction. The ultimate tensile strength of the alloy is 599 MPa， and the elongation reaches 15.4%. After aging treatment of 120 ℃/30 h， fine η （MgZn₂） and T（AlZnMgCu） strengthened phases precipitate in the microstructure， which further improve the properties of the alloy. The corresponding tensile strength reaches 736 MPa， and the elongation is 10.6%.

Additive friction stir deposition （AFSD） is a technology with several advantages for aerospace manufacturing. It is particularly valuable because it can deposit materials at low temperatures while retaining high quality and efficiency. This article introduces the operations of AFSD in detail and investigates its effect on three types of precipitation-reinforced aluminum alloys. Key challenges hindering the production of high-strength aluminum alloy components through AFSD are highlighted. AFSD utilizes solid-phase deposition to avoid problems like porosity and thermal cracking that can occur with other types of deposition， such as laser and arc depositions. However， the slow cooling of the deposited metal and the long residence time in the sensitive temperature range can cause issues. Subsequent layers exert a thermal effect on the previous layers during the AFSD process. This can lead to coarsening of the precipitates in the middle and lower regions， resulting in decreased strength in these areas. The top layer remains unaffected， but has poorer mechanical properties compared to the base material. To improve performance， aging treatment can be used to cause reprecipitation of some elements dissolved during AFSD， but it does not reach the values achieved by solid solution and aging （T6） treatment. T6 treatment after AFSD can renew uniformly distributed fine-strengthening precipitates， but it triggers abnormal grain growth （AGG） in the deposited material. Therefore， it is generally not recommended to subject solution treatment to metals deposited with AFSD. Further research should focus on alloy design， composite reinforcement and innovative techniques， which are essential to obtain high-strength precipitation-reinforced aluminum alloy components through AFSD.

To promote the further application of high-strength aluminum alloys in the aviation field，the 7050-T7451 aluminum alloy with 4 mm thickness is carried out by laser-melt inert-gas（MIG）hybrid welding. The results show that a well-formed weld seam can be obtained with reasonable matching of welding parameters，while welding at higher speeds is easy to produce cracks. When the welding speed is controlled at 0.9 m/min or below，and the weld back-width ratio is controlled above 0.4，the cracks and porosity defects can be effectively suppressed. The weld zone is mainly composed of equiaxed grain structures with significant differences in size. Near the fusion zone，there is a fine-grained layer approximately 20-50 μm wide，and only a minimal amount of columnar grains forms adjacent to this fine-grained layer. No phase transformation or recrystallization occurs in the heat-affected zone. The as-welded joint achieves an average tensile strength of approximately 377 MPa， equivalent to about 73% of the base metal strength， significantly outperforming the tensile properties of laser self-fusion welded joints.

To study the corrosion behavior and differences between 1070A and 6063 aluminum alloys in simulated marine atmospheric environments， the corrosion processes of 1070A and 6063 aluminum alloys in marine atmospheric environments are simulated by indoor cyclic salt spray experiments. The corrosion morphology， pitting parameters and the corrosion products of the 1070A and 6063 aluminum alloys are observed and detected by ultra-depth-of-field microscope and X-ray diffractometer respectively. The corrosion mass loss of 1070A and 6063 aluminum alloys is analyzed by corrosion kinetics methods. The differences of corrosion behaviors between the 1070A and 6063 aluminum alloys are analyzed by electrochemical impedance and polarization curves. The test results show that pitting corrosion is the main corrosion form on 1070A and 6063 aluminum alloys in the simulated marine atmospheric environment. With the extension of corrosion time， the average pitting depth， the maximum pitting depth and the pitting density gradually increase. The corrosion behaviors of 1070A and 6063 aluminum alloys are similar in the early stage of corrosion test. However， the pitting depth and pitting density of 6063 aluminum alloy doubled in the later corrosion stage， which is due to the re-cracking of the surface corrosion layer， resulting in a serious increase in the corrosion degree of 6063 aluminum alloy. What’s more， the corrosion mass loss and corrosion time of both 1070A and 6063 aluminum alloys show a power exponential relationship. Combined with the analysis of electrochemical impedance spectra and polarization curves， it is confirmed that the 6063 aluminum alloy is more susceptible to corrosion in simulated marine atmospheric environments， with a higher degree of corrosion compared to 1070A aluminum.

With the widespread application of carbon fiber reinforced polymer （CFRP） in the aerospace field， studying the friction performance at the interface of CFRP and aluminum alloy connections has become increasingly important. This study experimentally investigates the influence of surface microtexture parameters on the friction performance at the aluminum alloy-CFRP interface. The results indicate that both contact pressure and microgroove geometric parameters significantly affect the interface friction performance. As the contact pressure increases from 7.5 MPa to 30 MPa， the sliding friction coefficient significantly decreases， primarily due to the formation and enhancement of a self-lubricating film. Under high contact pressure， the microstructures on the aluminum alloy surface embed into the CFRP plate， creating a plowing effect. The micro-cutting action generates epoxy resin debris that fills the microstructure grooves， forming a stable lubricating film. The groove depth has the most significant impact on friction performance， with a groove depth of 31.8 μm significantly reducing the sliding friction coefficient to 0.197. The synergistic effect of contact pressure and microtexture geometric parameters markedly improves the interface friction performance and connection strength. This study provides theoretical basis and practical guidance for optimizing composite material connection technology.

An environmentally friendly conversion coating is prepared on AZ91D magnesium alloy surface by chemical conversion method using tannic acid as the coating forming agent to improve corrosion resistance. The acid regulating the pH value of the conversion solution is selected by contrast experiment. The pH value， reaction temperature， and conversion time are optimized by the Box-Behnken test， and the optimum process conditions are obtained. The effect of pH value on the corrosion resistance of the conversion coating is also discussed. CuSO₄ pitting time and electrochemical experiments are used to judge the corrosion resistance， SEM and EDS are used to characterize the coating surface morphology and element composition of AZ91D magnesium alloy. The results show that the optimum process of tannic acid conversion coating is as follows： tannic acid content 10 g/L， pH value 2.7 （hydrochloric acid regulation）， reaction temperature 41 ℃， conversion time 15 min. The conversion coating has good corrosion resistance， uniform density， and the covering is complete. The coating is mainly composed of tannic acid hydrolysate and Mg²⁺ chelate. Box-Behnken test result shows that the pH value has a great influence on the corrosion resistance of the conversion coating. When the pH value is too low， the coating is rough and poorly compacted；while when the pH value is too high， the coating is thin and lacks continuity， which cannot completely cover the surface of the magnesium alloy.

The microstructure and mechanical properties of the samples located at the surface and core of the spray-quenched 2219-T6 aluminum alloy thick plate are studied. The results show that the second phase in the alloy consists of Al₃（Cu， Fe， Mn） crystalline phase with a size of 0.5-30 μm， submicron sized θ-Al₂Cu phase and T phase， as well as nano-level semi coherent precipitated θ′ and θ″ phases. During spray quenching， the surface of the plate cools faster， resulting in a higher density of the θ″ phase in that area. At room temperature， the tensile strength and yield strength of the surface layer are 427 MPa and 303 MPa， respectively， which are increased by 9.2% and 15.6% compared to that of the core layer. Meanwhile， the plasticity of the surface layer is lower than that in the core layer， which is related to the superior strengthening effect of the surface layer by the precipitation of the θ″ phase. The cracks in the samples propagate in a mixed mode of intergranular and transgranular propagation. Due to the lower relative slip resistance of dislocations precipitated in the core layer compared to the surface layer， dislocations are more likely to accumulate near large-sized crystalline phases and grain boundaries， leading to the formation of more secondary cracks in the sample during fracture process. In addition， the tensile fracture surfaces of the samples are mainly composed of ductile dimples， exhibiting obvious ductile fracture characteristics.

The mechanical properties of wire-arc additive manufactured （WAAM） 2319 aluminum alloy are significantly influenced by the distribution of precipitates. However， the non-equilibrium solidification microstructure under cold metal transfer （CMT） and its evolution mechanism during heat treatment remain unclear. 2319 aluminum alloy specimens are fabricated using CMT-ed WAAM， with some subjected to T6 heat treatment. The distribution of precipitates in the upper， middle， and lower regions of the specimens is systematically investigated before and after heat treatment to elucidate their correlation with mechanical properties and the underlying strengthening mechanisms. The results indicate that the as-deposited specimens exhibit an average tensile strength of 175 MPa. The lower region near the substrate， which contains the highest volume fraction （20.8%） of coarse θ phases， demonstrates the greatest tensile strength （192 MPa）. After T6 heat treatment， the volume fraction of θ phases in the upper， middle， and lower positions of the samples decreases by about 80%. Meanwhile， a large number of small needle-like θ′ phases are formed in the matrix， and these dispersed θ′ phases play a major strengthening role， making the average tensile strength of the sample reach 365 MPa. Both as-deposited and heat-treated samples exhibit three strengthening mechanisms： precipitation strengthening， solid solution strengthening， and grain refinement strengthening. The substantial strength improvement in heat-treated samples primarily originates from precipitation strengthening induced by the θ′ phases.

The corrosion behavior and electrical conductivity of 1050A aluminium alloy conduct materials in simulated marine and industrial atmosphere are studied in this paper. Cyclic wet-dry immersion test and mass loss measurement are carried out to investigate the corrosion behavior of 1050A aluminium conduct material. The corrosion morphology of aluminium is observed and analyzed by using ultra-depth field microscopy and optical profilometer. The electrical properties are tested by micro-ohmmeter， conductivity testing meter， and digital bridge， respectively. In addition， the development and variation of corrosion parameters such as corrosion mass loss， corrosion rate， surface roughness， and pit depth and diameter are explored. Under the simulated marine atmospheric environment， it is found that the corrosion mass loss of 1050A aluminium is small and the pitting characteristics are obvious， the maximum corrosion pit depth and diameter can reach 36 μm and 80 μm respectively. However， in the simulated industrial atmospheric environment， the corrosion pits of 1050A aluminium are dispersed and the development of pitting parameters is not obvious， while the corrosion mass loss has the development trend of uniform corrosion. Moreover， the on-resistance and 20 ℃ resistance values of 1050A aluminium conductor parts increase obviously， and the conductivity decreases significantly with the development of corrosion in two typical atmospheric environments. In summary， the corrosion behavior and development law of aluminium conductors in simulated marine and industrial atmosphere are significantly different. The pitting corrosion characteristics of aluminium conductors are obvious， and the conductivity is closely related to the depth of corrosion pits in simulated marine atmosphere. However， the corrosion mass loss of aluminium conductor develops monotonously， and the conductivity has a high correlation with the corrosion mass loss in simulated industrial atmosphere. Therefore， the development trend of electrical conductivity of aluminium conduct materials in marine and industrial atmosphere can be predicted by pit depth and corrosion mass loss parameters respectively.

As the key lightweight materials for vehicle manufacturing and national defense， magnesium alloy’s low absolute strength and poor formability at room temperature limit its further application in related fields. At present， extrusion and rolling are the important means to produce high performance magnesium alloy sheet， and high strength and plastic structure control is the key technology of high strength and toughness and high formability magnesium alloy. In this paper， the latest research progress in microstructure and mechanical properties regulation of high strength and tough rolled rare earth magnesium （Mg-RE） alloy is reviewed. The microstructure regulation of Mg-RE is mainly discussed in terms of multi-component alloying composition design and rolling process innovation， so as to improve the properties of magnesium alloys. It is pointed out that the future research and development of low-cost high strength and toughness magnesium alloy sheet should be based on the in-depth exploration of process-structure-property relationship， which can provide reference for the composition design of rolled magnesium alloy and the preparation of high performance magnesium alloy from the perspectives of multi-component alloying composition design and high efficiency rolling process.

Magnesium alloy is a lightweight metallic material with huge potential for application in automobile， rail transit and aerospace， it can provide a solid support for the green and low-carbon development of China’s manufacturing industry. However， Traditional magnesium alloys have disadvantages such as low absolute strength， poor room temperature plasticity， low corrosion resistance and thermal conductivity. The rare earth（RE） elements are indispensable for enhancing the structural and functional properties of magnesium alloys. This paper reviews the effect of samarium （Sm） on mechanical properties， corrosion resistance and thermal conductivity of magnesium alloys. The mechanisms through which Sm influences magnesium alloys are systematically elucidated from various perspectives， including solute atoms， intermetallic compounds， precipitates， and RE textures. For the future development of magnesium alloys containing Sm， the following strategies are proposed： investigating the impact of Sm on the mechanical properties of magnesium alloys at elevated temperatures； optimizing composition and heat treatment to control microgalvanic cathodic reactions and enhance corrosion resistance； conducting research on the effects of twins， dislocations， and textures on the thermal conductivity of magnesium alloys containing Sm， and establishing corresponding prediction models.

Taking ZM5， ZM6， and WE43 commercial magnesium alloy samples as research objects， the influence of key geometric parameters such as plate thickness， cross-sectional shape， and connection method （including angle， radian， and position） on the combustion characteristics of Mg alloy components is investigated. The results show that increasing the thickness of plates proportionally extends ignition time； rod samples with a circular cross-section exhibit the lowest flame propagation rate due to their maximum S / l_{\mathrm{c}} (ratio of cross-sectional area to cross-sectional circumference）， demonstrating the best flame resistance； the closer the connection angle is to 90°， the greater the curvature of the connection arc， and the more central the connection position， the more effective the inhibition of flame propagation. Therefore， to investigate the combustion characteristics of complex Mg alloy components， it is essential to extract key characteristic parameters such as plate thickness， cross-sectional shape， and connection method （angle， radian， and position） during the simplification process， thereby faithfully reflecting the combustion behavior of these components. These findings provide a theoretical basis for the fireproof design of Mg alloy components and the simplified design of combustion simulation for complex Mg alloy components.

The crystal internal stress and texture evolution of six-pass hot rolled ZK61 magnesium alloy plate are studied by means of combining macroscopic finite element simulation and microscopic crystal plasticity analysis. According to the rolling experiment and tensile test， the corresponding synchronous hot rolling model is established and simulated， and the simulation results are entered as boundary conditions in the polycrystalline plasticity model based on Voronoi diagram. Then the crystal plasticity finite element method is used to simulate the synchronous hot rolling of the polycrystalline model， and the plastic parameters and texture pole figures of the hot-rolled ZK61 magnesium alloy in each pass are obtained. Compared with the tensile test results and the texture pole figures derived from the electron backscatter diffraction experiment， the crystal plastic deformation and texture evolution mechanism of the hot-rolled ZK61 magnesium alloy under different passes are summarized. The results show that there are a large number of twins and dynamic recrystallization in the ZK61 plate after multi-pass hot rolling， the grain homogenization and refinement effect is obvious. The pole intensity of basal texture is correlated with the whole rolling passes， the peak misorientation angle of the alloy under different passes has a quite diversity （8°， 28°， and 88°）， and the mechanical properties of the alloy are improved. The alloy strength is increased by 7.55%， and the elongation is achieved by 19.5%. The results can provide reference for improving the plastic processing ability of magnesium alloy.

Defects are the main factors affecting fracture behavior of casting materials. The fracture behavior of high pressure casting aluminium alloy is predicted using Gurson-Tvergaard-Needleman （GTN） damage model combined with finite element simulation software. The results show that damage parameters suitable for high pressure casting aluminum alloy materials are obtained through finite element reverse fitting， with a nucleated void volume fraction f_{\mathrm{N}} = \mathrm{0.12}， critical void volume fraction f_{\mathrm{c}} = \mathrm{0.001}， and fracture void volume fraction f_{\mathrm{F}} = \mathrm{0.001}. At the same time， fracture behavior prediction based on microscopic features is carried out by simplifying the pore morphology as ellipsoids and ignoring pores with volumes less than 0.001 mm³， to avoid low efficiency and non convergence in finite simulation calculations. The applicability of the two models in predicting the fracture behavior of casting materials is compared， and it is concluded that the finite element simulation combined with damage mechanics has higher computational efficiency， but the finite element simulation based on microscopic characteristics has higher prediction accuracy.

A wire-based friction stir additive remanufacturing （W-FSAR） method is proposed to address large cracks and material loss in aluminum alloy components during production and service. The W-FSAR tools consist of a wire feeding device， a stationary sleeve， and a screw-structured stirring head. This method effectively fills and repairs 10 mm-width and 2 mm-depth groove defects in aluminum alloy components. The results indicate the repaired sample has high repair efficiency， smooth morphology， homogeneous microstructure， and excellent mechanical properties. The dynamic recovery and recrystallization processes refine the grain size to 1.59 μm. The ultimate tensile strength and elongation of the repaired samples are （410±8） MPa and （11.9±0.9）%， respectively， which increase by 26% and 159% compared to the worn-out specimens. There are numerous dimples on the fracture surface， exhibiting typical ductile fracture characteristics.

As lightweight and high-performance structural materials， nano-Al₂O₃ reinforced aluminum matrix composites can achieve lightweight energy saving and emission reduction， and have broad application prospects in aerospace， automotive industry， shipbuilding， national defense， and 5G electronic communication. In this paper， high energy ball milling powder metallurgy method， ultrasonic assisted casting method， friction stir method， additive manufacturing method， in-situ reaction method and other nano-Al₂O₃ reinforced aluminum matrix composite preparation technologies are introduced. The effects of nano-Al₂O₃ reinforcement， the interface microstructure between the reinforcement and aluminum matrix， the size and content of the reinforcement， the grain size of the aluminum matrix，the dispersion of the reinforcement， and the microstructure design on the mechanical properties of nano-Al₂O₃ reinforced aluminum matrix composites are analyzed and summarized. The main strengthening mechanisms of nano-Al₂O₃ reinforced aluminum matrix composites and the coupling forms of each strengthening stress are also summarized. Finally， the future development direction of nano-Al₂O₃ reinforced aluminum matrix composites in the aspects of large-size preparation technology with high reinforcement volume fraction， heterogeneous configuration optimization， and the integration of high-strength and heat-resistant structure and function are prospected.

During the wire-arc additive manufacturing process， Al5356 straight-wall components are fabricated by imparting lateral swings of varying frequencies and amplitudes to the welding gun. The impact of these swinging arcs on the forming quality， pore distribution， microstructure， and mechanical properties of the components is evaluated through surface waviness calculations， microstructural analysis， and mechanical tensile tests. The results show that incorporating the arc swing technique in the manufacturing process significantly enhances the forming accuracy， compactness， microstructural uniformity， and mechanical properties of the straight-wall samples. Within the experimental parameters， applying an arc swing reduces the surface waviness of Al5356 straight-wall samples by 60% compared to those produced without an arc swing. Additionally， the porosity and maximum pore diameter are decreased from over 0.65% and 33 µm to below 0.20% and 10 µm， respectively. The average tensile strength in both the X-direction （deposition direction） and Z-direction （build direction） increases by approximately 13% and 15%， respectively， while the average elongation improves by about 27% and 25%， respectively. Notably， the frequency of the arc swing has a more pronounced effect than the amplitude in enhancing surface quality， pore dispersion， and pore diameter reduction in the deposited components. High-frequency arc oscillation exerts a potent stirring effect on the melt pool， leading to a more uniform temperature distribution across the transverse direction of the deposited weld path. The observed enhancement in mechanical properties is primarily attributed to the reduction of pore defects and the homogenization of the microstructure. Therefore， the proper application of the arc swing technique in wire-arc additive manufacturing holds significant promise for improving the forming quality and mechanical properties of components.

The micro-sized second-phase and recrystallized structure has an important influence on the strength and toughness of 5083-O alloy. In order to acquire the morphological feature of the micro-sized second-phase particles and recrystallized particles in 5083-O alloy， multi-slices EDS data at a low acceleration voltage of 5 kV and EBSD data at 20 kV of the alloy are collected based on the double beam microscope system. These multi-slices data are restructured into three-dimensional types by Avizo software. The size， morphology， distribution， and volume fraction of the chief second-phases （Mg₂Si phase and Fe-rich phase） and recrystallized structure are obtained through the restructured data. The results show that the volume fractions of Mg₂Si phases， Fe-rich phases， and recrystallized particles in the studied alloy are 0.46%，0.25%， and 11.7%， respectively. Most Mg₂Si particles have smooth surfaces， with shapes of near-spherical， near-ellipsoid， or rod-shaped， and elongate along the rolling direction. The Fe-rich phases in the alloy are angular or subangular， and have relatively low spherical degrees. The three-dimensional EBSD restructure data show that the smaller size recrystallized particles have the higher spherical degrees， and the bigger size recrystallized particles have the lower spherical degrees. It is found that the recrystallized grains grow up from the small sphere recrystallized particles during the annealing process， and grow fastest along the rolling direction. The morphology of recrystallized particles is more truly reflected by three-dimensional EBSD results.

The 6061 aluminum alloy billets are subjected to solution quenching treatment under a solution heat treatment condition of 550 ℃ for 30 min. After quenching， the billets are artificially aged at 140 ℃ for 6 h to 18 h to obtain pre-hardening （PH） billets. The formability and mechanical properties of the pre-hardening 6061 aluminum alloy billets are evaluated using room-temperature Erichsen cupping tests and uniaxial tensile tests. Additionally， the stamping trials for hat-shaped beam components are conducted to verify the feasibility of this technique for engineering applications. The results show that the yield strength （YS） of the PH-12 h pre-hardening billets is 186 MPa higher than that of the O-temper billets， and the tensile strength （TS） is 215 MPa higher than that of the O-temper billets， while the elongation （EL） and cupping values are comparable to those of the O-temper billets. The PH-18 h pre-hardening billets exhibit a maximum tensile strength of 391 MPa after 10% deformation， significantly exceeding that of the T6-temper aluminum alloy， demonstrating that the pre-hardening billets possess excellent strength-ductility balance. Furthermore， the hat-shaped beam components formed from pre-hardening billets exhibit tensile and yield strengths superior to those of the T6-temper aluminum alloy.

Single point incremental forming （SPIF） is a highly flexible manufacturing process widely utilized in the aerospace industry， particularly suited for customized and small-batch production components. However， the appropriate range of process parameters suitable for different models remains undefined， necessitating extensive parameter testing. An orthogonal experiment is conducted to perform a multi-factor analysis of variance， discussing the influence of parameters such as sheet thickness， angle， incremental amount， feed rate， and rotational speed on the maximum forming depth. Based on the experimental results， a regression model using the Adaboost algorithm is developed to predict the forming depth of 6061 aluminum alloy thin sheets at the forming diameter of 100 mm. The results indicate that the influences of single factors on the maximum forming depth in descending order of significance are： thickness， layer increment， angle， feed rate， and rotational speed. Under the optimal forming conditions achieved at the fastest forming speed， the maximum forming angle is 70°， the sheet thickness is 1 mm， the layer increment is 0.2 mm， the feed rate is 2000 mm/min， and the rotational speed is 2000 r/min. Furthermore， the regression model created based on the orthogonal experiment demonstrates high accuracy， correlating well with both the Abaqus simulation results and the actual experimental outcomes. The maximum error between the four groups of tests and simulations is 4.24%， while the maximum error with the actual forming results is -2.45%.

This paper proposes a non-isothermal solid solution-forging integrated hot forming process for 7075 aluminum alloy. After solid solution treatment， the aluminum alloy is directly placed into the mold for forging， then quenched and subjected to artificial aging treatment. The influence of water entry temperature and aging parameters on the microstructure and properties of 7075 aluminum alloy is studied under this process， through the construction of a temperature-time-property（TTP） curve. Additionally， machine learning techniques are integrated to optimize and match the key process parameters. The results reveal that the nose temperature of the TTP curve is 315 ℃， and the mechanical properties of the alloy increase with the increase of water temperature after aging， a double-peak phenomenon after non-isothermal forging and aging is observed. When the inlet temperature is 380 ℃， the optimal aging parameters are 115 ℃-26 h and the peak hardness is 182HV. After training， the prediction accuracy of the BP neural network model is 94.9977%. Experimental verification of the optimal process parameters predicted by the model shows that its prediction similarity is 96.9%. Compared with traditional forging processes， this process can achieve high mechanical properties than traditional forged T6-state 7075 aluminum alloy while reducing procedural steps and energy consumption.

The effect of different cold drawing deformations and annealing temperatures on the microstructure and tensile properties of Al-Si-Sc-Zr alloy wires is investigated by the mean of electron backscatter diffraction technique. The results show that the grains are elongated and refined along the drawing direction， accompanying with the fibrous structure and a typical〈111〉deformation texture with strain increasing. However， when the drawing strain increases from 0.61 to 0.76， the average grain size increases and the proportion of low-angle grain boundaries decreases due to the recrystallization behavior in the grains. Furthermore， the tensile strength and yield strength of the wire increase to 181.5 MPa and 166.5 MPa， respectively， due to the work hardening induced by the cold drawing process. When the cold-drawn wires are subjected to the annealing treatment at 350-450 ℃ for 2 h，the fibrous cold-drawn structure is transformed into fine equiaxed grains， and the typical cube texture ｛100｝〈001〉 is formed. This annealing treatment can significantly eliminate the work hardening caused by the cold drawing. In this case， the yield strength decreases from 166.5 MPa to 84.0 MPa， meanwhile the elongation after fracture increases from 2.1% to 9.5%. The annealed structure is uniform and stable， which is favorable to subsequent cold drawing processes.

As-deposited parts of 2024 aluminum alloy are fabricated by cold metal transfer and pulse （CMT+P） hybrid wire arc additive manufacturing. The distributions of pore defects， grain morphology， and secondary phase precipitation of CMT+P wire arc additive manufacturing 2024 aluminum alloy， and the influence of different process parameters on pore defects， grain morphology and secondary phase precipitation， and corrosion resistance are investigated. The results show that the pores of the as-deposited parts of 2024 aluminum alloy are mainly distributed near the fusion line. In the same heat input， the larger wire feed speed and travel speed result in higher porosity. In a deposition layer， the upper part is the equiaxed grain without preferred orientation， and the lower part is the columnar grain with preferred orientation. In the same heat input， the texture is weakened and the percentage of equiaxed grains is increased due to the fine grain region in the higher wire feed speed and travel speed. The precipitated secondary phases are mainly Al₂CuMg， Al₂Cu， and rich-Fe， Mn phases. The secondary phases distribute continuously along the grain boundaries. In the early stage of corrosion， the main factor affecting the corrosion resistance of as-deposited parts is the precipitation amount of Al₂CuMg. The better local corrosion resistance is mainly caused by lower Al₂CuMg phase fraction in lower wire feed speed and travel speed.

The microstructure control and corrosion resistance of aluminum alloys fabricated by wire and arc additive manufacturing（WAAM） are important issues that must be studied in engineering applications. The 5356 deposited part is produced by a CMT （cold metal transfer） system. The microstructure and hardness are characterized by metallurgical microscope， X-ray diffractometer （XRD）， scanning electron microscope （SEM） and micro-hardness tester， and the corrosion resistance behavior is studied by using electrochemical workstation， slow strain rate stress corrosion testing machine. The results show that the microstructure of 5356 WAAM aluminum alloy is composed of α-Al matrix and β（Al₃Mg₂） phase. The grains in the deposition layer are columnar crystals with an aspect ratio of ≤2， and the β（Al₃Mg₂） phase exists mainly as finely dispersed particles， while the grains in the interface layer are recrystallized equiaxed grains with smaller size， and the β（Al₃Mg₂） phase is predominantly distributed in large discontinuous blocks along the grain boundaries， with fewer fine granular β（Al₃Mg₂） phase within the grains， leading to a reduction in the matrix strengthening effect. The self-corrosion current density of the deposited layer is 23% of that of the interface layer， which may be caused by the content and morphology of β（Al₃Mg₂） phase. The stress corrosion sensitivity index at a slow strain rate of 5356 WAAM aluminum alloy is 0.57， and samples experience fracture and failure at the interface layer in both silicone oil and 3.5%NaCl solution medium. This is attributed to the lower strength at the interface layer matrix and shearing effect played by large intergranular β（Al₃Mg₂） phase in silicone oil inert medium， while the β（Al₃Mg₂） phase dissolves preferentially in the 3.5%NaCl aqueous solution， and intergranular corrosion propagation is accelerated under tensile stress.

Based on the response surface design， the optimal process parameters for single-side friction stir welding（FSW） of 2195 Al-Li alloy sheets are studied. It is found that the higher the rotation speed and the lower the welding speed， the higher the tensile strength of the welded joint. The results show that in the single-side FSW， when the pin length is 2/3 length of the thickness of the plate， the root of the weld appears unwelded defects， the fracture form of the welded joint is between brittle and plastic fracture， and the tensile strength of the joint is poor. Based on the optimum process parameters of single-sided welding， double-sided FSW can overcome the unwelded defects at the root of single-sided welding. Under different tool pressures， when the stirring head speed is 1600 r/min， the feed speed is 150 mm/min， and the pressure is 0.1 mm， the double-sided welding can improve the tensile strength of the welded joint by about 10% and the elongation of the welded joint by 10%. In two-sided FSW， the material flow on the forward side is obvious， and the fracture mode of the welded joint is a plastic fracture. In double-sided welding， the plate is subjected to secondary stirring and heating， resulting in increased softening of the material in the welding area.The microhardness of the double-sided welded joint is further reduced than that of the single-sided welding.

Developing aluminum alloys with high strength， high conductivity， and thermal conductivity is the key to applying aluminum alloy materials in electrical， electronic， and heat dissipation industries. Aiming at these requirements， the effect of adding trace Eu to Al-Mg-Si-Fe alloy on the microstructure and properties of vacuum die-casting products are systematically studied. The results show that the alloy modification effect of adding 0.05%-0.25% （mass fraction/%， the same below）Eu first increases and then decreases. When adding 0.15%Eu， the grain is significantly refined， and the precipitation of the brittle （FeSiAl） eutectic phase and long plate-like eutectic Si in the alloy is restrained. The solid solubility of Mg in the aluminum matrix is reduced， and the lattice distortion of the alloy is reduced. Therefore the mechanical properties， electrical conductivity， and thermal conductivity of the alloy have been improved simultaneously. The Al-Mg-Si-Fe-0.15Eu alloy has a thermal conductivity of 68.50 mm²/s， electrical conductivity of 51.4% ICAS， tensile strength of 148 MPa， and elongation of 16.20%. Compared with the original Al-Mg-Si-Fe cast alloy， the thermal conductivity increases by 12.50%， the electrical conductivity increases by 1.4% ICAS， the tensile strength increases by 20 MPa， and the elongation increases by 5.40%. The tensile fracture morphology of the alloy changes from quasi-cleavage fracture to ductile fracture.

The xTiB₂/Al-5Cu-0.85Mn-0.35Mg-0.5Ag（x=0%，1%，3%，5%，mass fraction， the same below） composites are fabricated by a mixed salt reaction method， followed by single-stage and interrupted aging treatments. The effects of differing thermal processing regimes on the microstructural and mechanical properties of the materials are systematically studied. The results indicate that as the TiB₂ content increases， both the hardness and strength of the composites show a continuous upward trend， while the elongation gradually decreases. When the TiB₂ content is 3%， after single-stage aging treatment （175 ℃/3 h）， the composite’s yield strength， tensile strength， elastic modulus， and elongation reach 465.1， 496.8 MPa， 78.9 GPa， and 4.8%， respectively. After undergoing an interrupted aging process at 175 ℃ for 1.5 h followed by 150 ℃ for 13.5 h， the yield strength， tensile strength， and elastic modulus of the composites increase to 479.3， 507.2 MPa， and 79.1 GPa， respectively， representing increases of 5.9%， 2.1%， and 0.25% compared to the single-stage aging treatment， with an elongation of 4.1%. The secondary aging temperature significantly affects the precipitation sequence of aging precipitates， which is the main reason for the substantial improvement in material properties. When the secondary aging temperature is 100 ℃， the θ'-Al₂Cu phase is the primary aging strengthening phase. At a secondary aging temperature of 150 ℃， the Ω-Al₂Cu phase becomes the main aging strengthening phase.

To meet the application requirement of advanced aviation engines for complex shell castings of high-strength and heat-resistant aluminum alloys， the process and mechanical properties of a new type of the Al-Si-Cu-Mg-Sc high-strength and heat-resistant aluminum alloy are analysed in comparison with ZL101A and ZL205A cast aluminum alloys. Design and experimental verification of the metal casting process for the complex casing of the oil pump are carried out by using the high-strength and heat-resistant aluminum alloy， and the quality of the casting products is evaluated. The results indicate that the new high-strength and heat-resistant Al-Si-Cu-Mg-Sc alloy shows better casting fluidity and hot cracking resistance than the ZL205A high-strength cast Al alloy. The qualification rate of the complex shell of its metal casting oil pump is comparable to that of the same type of shell ZL101A. The average tensile strengths at room temperature of the separated test bar of casting and test specimen from casting itself of the new alloy are higher than 420 MPa， which are significantly higher than that of ZL101A alloy， while the tensile strengths at 250 ℃ are superior to ZL205A alloy. The surface quality， internal quality， airtightness， and pressure resistant performance of the casting case all meet the design requirement of the product.

Under certain solid solution time conditions， the solid solution temperature determines the degree of supersaturation and recrystallisation of the matrix after quenching， and is an important factor in enhancing the performance of the material after aging treatment. Through the solid solution heat treatment of 2050 Al-Li alloy extruded bar at different temperatures for 2 h and artificial aging treatment at 170 ℃ for 40 h， combined with a variety of property testing methods and microstructure observation methods， the effect of solid solution temperature on the microstructure and properties of 2050 Al-Li alloy extruded bar was studied. The results show that the residual phase is continuously redissolved with the increase of the solid solution temperature， and the residual phase is mainly iron-containing phase when the solid solution temperature is 525 ℃.The slight overheating structure appears in the bar when the solid solution temperature is 550 ℃， and the serious overheating structure appears in the bar when the solid solution temperature reaches 570 ℃. Local recrystallization occurs when the bar is heated to 500 ℃， and complete recrystallization occurs when the solid solution temperature reaches 570 ℃. When the 2050 Al-Li alloy extruded bars are solution treated at different temperature （450-550 ℃） and aged at 170 ℃ for 40 h， the number of θ′ and T₁ phases increases with the increase of solid solution temperature， and the strength increases rapidly and then slowly，when the solution treatment temperature is 550 °C， the yield strength and tensile strength of extruded rods are the highest， which are 505 MPa and 567 MPa， respectively； the elongation decreases rapidly at first and then remains stable with the increase of solid solution temperature， decreasing from 13.4% at 450 ℃ to 10.7%-10.4% at 500-550 ℃.

The effects of the solid solution on the microstructure and mechanical properties of 6451 Al alloy sheets were investigated by using conductivity and tensile tests， combined with OM and SEM observations. The results show that when the solid solution temperature is 560 ℃， recrystallization occurs in the sheet at 3 s of solution treatment. When the solution time is extended to 5 s， the Mg₂Si particles are slowly dissolved. When the time is extended to 7 s， the equiaxial grains are formed after the complete recrystallization， a large amount of Mg₂Si particles are dissolved， and the strength of the sheet is rapidly increased. With the further extension of the solution time， the growth rate of the strength of the T4P-stated sheet slows down obviously， and the increment of the yield strength after baking is basically unchanged. After the solution time of 30 s， there is no obvious change in the grain size. When the solution time is increased to 60 s， the Mg₂Si particle is completely dissolved， and the yield and tensile strengths of the T4P-stated sheet are improved to 125 MPa and 247 MPa， respectively， with a better elongation of 30%. The functional relationship model between the yield strength and solid solution variation of the T4P-stated sheet based on classical diffusion theory is established according to the research results.

Utilizing Ca and TiH₂ as the thickening agent and blowing agent， respectively， Al-0.16Sc， Al-0.21Sc， and Al-0.16Sc-0.17Zr cellular foams with porosity of （72±0.5）% were successfully fabricated by the melt-foaming method. The microstructure and compressive strength of the foams with isochronal aging treatment were investigated. The results show that during isochronal aging between 200 ℃ and 600 ℃， Al-0.16Sc and Al-0.21Sc foams achieve their peak yield strengths （about 21.4 MPa and 26.8 MPa， respectively） at 325 ℃ due to the precipitation strengthening of Al₃Sc/Al₃（Sc_{1- x} Ti _x ）. Unlike the Al-Sc foam， the yield strength of the Al-0.16Sc-0.17Zr alloy foam reaches 23.7 MPa at 325 ℃ and 24.7 MPa at 400 ℃， representing an increase of 100.8% and 109% than those of the cast alloy， respectively. Zr addition not only significantly enhances the strength of the Al-Sc foams， but also effectively affects the coarsening of the Al₃Sc/Al₃（Sc_{1- x} Ti _x ） precipitate.

The 6061-T6 ultra-thin aluminum alloy with a thickness of 0.5 mm was welded using micro-joint friction stir welding technology. The effects of three kinds of stirring heads with different shaft shoulder morphology on the forming quality， microstructure， mechanical properties， welding thermal cycle， and force process of the 6061-T6 thin-wall butt joint were studied. The flow behavior characteristics of the plastic metal in the three welding cross-sections were analyzed in sequence. The results show that the forming effect of the weld surface is significantly affected by welding heat input. The hardness distribution trend of the joint cross-section formed by three kinds of stirring heads with different shaft shoulder morphology is a “W” shape. The highest hardness values in the center of the nucleation zone and the lowest hardness values in the thermo-mechanical affected zone of the needle-free three-involute diversion groove shaft shoulder welded joint are the highest among the three shaft shoulder welded joints. The mechanical properties of the joint formed by the three-involute guide groove with the needle shaft shoulder are outstanding， and the tensile strength， yield strength， and elongation after fracture are higher than those of the other two. The three tensile fracture forms are mainly ductile fractures. The process parameters of the thermal cycle and force can accurately reflect the changing trend of the welding state. The energy required to maintain the weld metal softening is from the heat generated by friction between the shaft shoulder and the workpiece and the work done by the axial and forward forces of the shaft shoulder. The axial force and forward force changed with the softening degree of the welded metal， playing a dynamic regulating role in the migration of plastic metal in the weld. The shoulder surface has a strong effect on the upper part of the weld， driving the plastic metal migration between the forward side and the backward side. The needle of the stirring head promotes the interaction between the plastic metal and the backing plate， providing a driving force for the flow of the upper and lower parts of the weld metal. The optimal heat generation potential is the combined result of the stirring needle and the involute groove， which work together to form a well-formed weld.

The 316 stainless steel coatings with different thicknesses （SSC2， SSC4， SSC7， SSC10） were deposited on the magnesium alloy surface by using the HVOF method. The microstructures， deposition characteristics， residual stresses and immersion corrosion characteristics of the coating were investigated. The results reveal that due to the lower melting point and hardness of magnesium alloy， spray particles are prone to invade the substrate and melt its surface， causing particle escape or splashing， resulting in lower deposition efficiency； after depositing thinner coatings （SSC2 and SSC4）， the escape or splashing behavior of deposited particles reduces significantly， and the deposition efficiency increases； when the deposition thickness increases to SSC7 or above， the surface temperature of the deposition increases， particle splashing gradually increases， and the porosity and oxide content of the coating surface increase. Furthermore， as the coating thickness increases， the residual compressive stress of the coating decreases， the stress distribution becomes more uniform， and the number of penetrating pores in the coating decreases significantly， approaching zero. There are penetrating pores inside the SSC2 and SSC4 coatings， and the effective protection time is extremely short. The thick coatings （SSC7 and above） still have a protective effect after soaking in 3.5% （mass fraction） NaCl solution for 720 h.

Al-5%Fe-xNi alloys （x=0%，1.5%，5%，7.5%，10%， mass fraction，the same below） were prepared by the traditional casting method， and the morphology and size changes of the primary phase in the alloys after Ni addition were observed. The transformation of the solidification process of the alloys and the effect of Ni addition on the primary phase and eutectic structure were analyzed， and the influence of Ni content on the microstructure and thermal properties of the alloys was discussed. The results show that with the increase of Ni content， the primary phase changes from irregular bulk to needle-like. As the Ni content exceeds 5%， the eutectic structure decreases， and the primary phase changes to a regularly arranged Al₉FeNi phase. The addition of Ni significantly changes the solidification process of the alloys， resulting in the precipitation reaction of the primary phase from L→Al₁₃Fe₄ to L→Al₉FeNi or L+Al₁₃Fe₄→Al₉FeNi， and the eutectic precipitation reaction from L→α-Al+Al₁₃Fe₄ to L+Al₁₃Fe₄→α-Al+Al₉FeNi and L→Al₃Ni+α-Al+Al₉FeNi. With the increase of Ni content， the volume fraction of the precipitated phase increases， and the thermal conductivity and thermal expansion coefficient of the alloys decrease. The thermal expansion coefficient of the alloys decreases from 19.9×10^-6 K^-1 （@25-200 ℃） of Al-5%Fe to 17.6×10^-6 K^-1 （@25-200 ℃） of Al-5%Fe-10%Ni. The thermal conductivity and thermal expansion coefficient of the alloys are predicted by using the general effective medium theory （GEMT） model and the modified Turner model， respectively. It is found that the simulated values are in good agreement with the experimental values.

The effects of Cr on the microstructure of as-cast Al-Cu-Mg-Ag alloys and the distribution， size and number density of dispersoids after double-stage homogenization were investigated by OM， XRD， SEM-EDS and TEM methods. The effects of Cr on the dynamic recrystallization behavior of Al-Cu-Mg-Ag alloys under different equivalent strain were studied by high-throughput isothermal compression experiments. The results show that spherical Al₇（Cr， Mn） dispersoids with average diameter and number density of 67.4 nm and 4.7 μm^－2 are precipitated during the homogenization process， in addition to the rod-like T-Al₂₀Cu₂Mn₃ dispersoids. The opposite equilibrium distribution coefficient of Cr and Mn （K _Mn<1 vs K _Cr>1） reduces the area fraction of dispersoid-free zones from 29.5% to 13.8%， the average length of rod-like T-Al₂₀Cu₂Mn₃ decreases from 275.4 nm to 147.3 nm， and its number density increases from 3.5 μm^－2 to 10.4 μm^－2. EBSD and tensile test results indicate that the Al₇（Cr， Mn） dispersoids hinder the dislocation movement， reducing the transition from low-angle grain boundaries to high-angle grain boundaries during thermal compression， and inhibiting the dynamic recrystallization. The addition of Cr increases the mechanical properties of Al-Cu-Mg-Ag alloys at different temperatures， and the yield strength contributions of Al₇（Cr， Mn） dispersoids to the alloys at 25，250 ℃ and 300 ℃ are 21.9，16.2 MPa and 15.3 MPa， respectively.

The SiC/AlSi10Mg composites were fabricated via selective laser melting（SLM）. The phase characteristics， microstructure， anti-corrosion and wear resistance properties of SLM SiC/AlSi10Mg and SLM AlSi10Mg samples were investigated by XRD， SEM， EDS， EBSD， electrochemical test， and friction and wear test. The results show that in the 3.5% （mass fraction） NaCl solution， the corrosion current density of SLM SiC/AlSi10Mg （2.0827 μA/cm²） is lower than that of SLM AlSi10Mg （3.389 μA/cm²）， and the passivation film on the surface of SLM SiC/AlSi10Mg （7.1 nm） is thicker than that of SLM AlSi10Mg （1.9 nm）， indicating the SLM SiC/AlSi10Mg sample has better corrosion resistance than that of SLM AlSi10Mg. The reason can be attributed to that the addition of SiC causes the grain refinement， the increase of high grain boundary， and the interruption of the continuity of Al matrix， leading to the decrease of corrosion rate and the increase of corrosion resistance. In addition， the average microhardness for SLM SiC/AlSi10Mg composites （207.68±16.02）HV_0.2 is twice that of SLM AlSi10Mg alloy （103.58±7.41）HV_0.2， indicating its hardness and wear resistance are improved. Both the wear mechanisms of SLM AlSi10Mg and SiC/AlSi10Mg composites are mainly abrasive wear and oxidation wear.

Taking TiC_p/Al-5Cu-1.9Mg-0.9Mn composite materials reinforced with 0.27%（volume fraction）TiC particles as the matrix， the effects of different Sm element contents on the microstructure and mechanical properties of the composite material were investigated. The results show that the addition of the Sm element significantly refines the dendritic microstructure and facilitates the dissolution of the second phase during the solid solution treatment. Consequently， an increase in the density of precipitated phases， including T-Al₂₀Cu₂Mn₃ and S'-Al₂CuMg， was observed in the aged microstructure. When the Sm element content is high （0.3%， mass fraction， the same below）， the microstructure exhibits blocky insoluble rare earth-containing compounds. With the addition of the Sm， the composite materials show a gradual increase in yield strength at both room temperature and 250 ℃. However， it will cause a decrease in plasticity. When the Sm element content is 0.3%， the yield strength at room temperature increases from 246 MPa to 310 MPa， and the yield strength at 250 ℃ increases from 191 MPa to 220 MPa. The analysis suggests that the increase in strength is attributed to the microstructural refinement and the increased density of precipitated phases induced by Sm. Conversely， the reduction in plasticity is attributed to the presence of coarse blocky insoluble rare earth compounds cutting through the matrix， leading to the easy generation of crack sources.

The 7050 aluminum alloy was studied as the research object to investigate the coupling effect of heat treatment state （air quenching aging and water quenching aging） and macroscopic orientation （0°， 45°， and 90° concerning the rolling direction） on mechanical properties of the alloy. The results indicate that the precipitated phases in the water-cooled aged samples are small， uniformly dispersed， and the grain boundaries have narrow precipitate free bands. In the air-cooled aging state， the supersaturated solutes not only form coarse precipitates with semi coherent Al₃Zr as the core， but also precipitate a large amount along dislocations. In addition， compared with the water-cooled aging state， the grain boundary phase size in the air-cooled aging state increases significantly， and the precipitate free zone at the grain boundary widens significantly. The strength and elongation of samples with different macroscopic orientations are significantly reduced. The influence of macroscopic orientation on the difference in strength between two states of samples is relatively minimal， but it has a significant impact on the difference in elongation. When the tensile direction is at 45° to the rolling direction， the decrease in elongation induced by air cooling is the slightest， while the tensile direction is at 90° to the rolling direction， the maximum decrease is observed.

To explore the effect of micro-Zr alloying on the hot deformation microstructure of 6082 aluminum alloy and its subsequent recrystallization during heat treatment， the hot deformation behavior and micro-orientation evolution of 6082 aluminum alloy containing Zr at different strain rates （0.01，1 s^-1） were comparatively studied. The evolution process of grain structure before and after heat treatment was analyzed， and the regulatory effect of Zr addition on the thermally deformed sub-grains and recrystallization of 6082 aluminum alloy was further discussed. The results show that the addition of Zr makes the recrystallization of 6082 aluminum alloy during the hot deformation process mainly perform discontinuous dynamic recrystallization， and the recrystallization generated by the particle stimulated nucleation（PSN）mechanism also occurs， and minor Zr addition also plays a role in inhibiting recrystallization in the hot deformation process. After the micro-Zr alloying， the subgrain size decreases， the dislocation density increases， the recrystallization level decreases， and the recrystallization level of the sample at a higher strain rate is lower， and the addition of Zr promotes the generation of the discontinuous dynamic recrystallization of 6082 aluminum alloy during hot deformation.

Pure Mg has advantages of low density， good shock absorption performance and good biocompatibility， but its strength is low. Alloying is an important method to modify microstructure and properties of pure Mg. Sn has characteristics of low melting point， high eutectic temperature with Mg， high solid solubility in Mg， stable chemical properties and large output， which is appropriate to be an alloying element. The effects of alloying element Sn on microstructures and properties of Mg alloys were reviewed in this paper. Sn enriches at the front of the solid-liquid interface， dissolves in Mg matrix， reduces the ratio of critical resolved shear stress value of the pyramidal plane to that of the basal plane， and elevates the electric potential of Mg matrix. Mg₂Sn precipitates can hinder dislocation and grain boundary movement， and form galvanic corrosion cells with Mg matrix. Therefore， effects of Sn addition include grain refinement， age hardening and strengthening， improving plasticity， accelerating or reducing corrosion rate， enhancing discharge efficiency and discharge potential. At present， the main problems restricting the development of Mg-Sn alloys are slow aging， low hardness and strength. In the future， endeavors should be made to develop rapidly age-hardenable Mg-Sn alloys with high strengths， wrought Sn-containing Mg alloys with good ductility， and Sn-containing structural-functional Mg alloys.