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In order to improve the corrosion and heat resistance of Al-Mg-Si alloy conductor materials, Ce, Sc, Y and Zr were added in Al-Mg-Si alloy to regulate the microstructure. The Al-Mg-Si-Ce-Sc-Y alloy was designed with excellent pitting and intergranular corrosion resistance by obtaining the micron-sized Fe-containing second phase with a lower potential difference to Al matrix, more dispersed grain boundary precipitates with a higher proportion of Si particles, narrower width of PFZ and ideal distribution of intergranular precipitates. The Al-Mg-Si-Ce-Sc-Y alloy also maintained higher hardness, strength and electrical conductivity after overaging and annealing and the corrosion/heat resistance mechanisms were proposed. • The corrosion and heat resistance of Al-Mg-Si alloy conductors were further enhanced. • The mechanisms of pitting and intergranular corrosion mechanisms in Al-Mg-Si alloys were proposed. • The microalloying of Ce，Sc and Y in Al-Mg-Si alloys with high electrical conductivity was established. [ABSTRACT FROM AUTHOR]

Abstract To obtain the optimal mechanical properties, several processes including spray forming technology, two passes hot extrusion and substantial heating treatments were operated on an Al-Zn-Mg-Cu-Zr alloy. The characterization methods used in this study include tensile tests, X-ray diffraction, differential scanning calorimetry and microstructure observations by optical microscope, scanning and transmission electron microscopy. The typical characteristics were the refined grain, homogeneous precipitates and porosity in the as-deposited pre-forms. The ultimate tensile strength, yield strength, hardness and elongation improved significantly after two passes hot extrusion. A good combination of ultimate tensile strength at 704 MPa and elongation at 9.7% were achieved under peak-aged treatment. The best ultimate tensile strength was obtained at 732 MPa after re-aging and regression. It was main dimple fracture in the extruded and aging treated specimens while brittle fracture for the as-deposited. The secondary phases were main MgZn 2 and Al 3 Zr dispersoids throughout all the states. The contributions of grain boundaries, dislocations, solid-solution and precipitates on the yield strength were analyzed using a quantitative equation. Highlights • The spray forming technology was used to fabricate ultra-high strength aluminum alloy. • The alloy under RRA state obtained the highest ultimate tensile strength of 732 MPa. • The effects of dislocations, solutes and precipitates etc., on yield strength were calculated. • Precipitation was characterized as the main strengthening mechanism for aging states. [ABSTRACT FROM AUTHOR]

Millions of tons of iron-bearing manganese residue are produced as a by-product of the electrolytic manganese industry. And the environmental contamination caused by manganese residue has received increasing attention. This paper focuses on the recovery of iron and manganese from high iron-bearing manganese residues. Manganese ferrite in manganese residues is initially decomposed by oxidative roasting, and the intermediates are magnetized in a reductive roasting step. The roasted product is milled and subjected to multi-stage magnetic separation. The optimum conditions are as follows: roasting at 750 °C under air flow for 30 min, roasting in a CO atmosphere at 750 °C for 30 min, and separating under a magnetic intensity of 1000 G for weak magnetic separation and of 12,000 G for strong magnetic separation. The recovery and grade of iron in the iron concentrate were 72.29% and 62.21%, respectively, and those of manganese in the manganese concentrate were 90.75% and 35.21%, respectively. This study demonstrates that the combination of roasting and magnetic separation provides a promising process for the recovery of iron and manganese from high-iron-bearing manganese residues. [ABSTRACT FROM AUTHOR]

In order to improve the surface performance of Al-Zn-Mg-Mn-Zr extruded alloy, alumina coatings were directly prepared on the alloy in silicate electrolytes by direct current micro-arc oxidation technique. The relationship between discharge stages and technology parameters was studied, and then the growth behaviors, structure, composition and properties of coatings were further analyzed. Our work suggests that appropriately prolonging of the oxidation time at a low current density of 2 A/dm 2 can help to extend the action time of the micro-arc stage (Stage III) and to form a thicker layer with fewer inner defects. The compact inner structure promotes the hardness, elastic modulus as well as the corrosion resistance of the coatings. In contrast, the higher the current density, the earlier the discharge enters into the big arc stage (Stage IV), which has an adverse impact on the structure and properties of the coatings. In the Stage IV, the porosity of the coatings increases with the generation of mullite within the coatings comprise of γ-Al 2 O 3 and α-Al 2 O 3 . The growing direction of coatings changes from outward mainly to inward in the late stage of the micro-arc oxidation (MAO) process. [ABSTRACT FROM AUTHOR]

The superplastic behavior of Al–Mg–Sc–Zr samples with standard gauge size (18 mm by 6 mm) were prepared using simple rolling and were tested in the temperature range from 450 °C to 525 °C at strain rates ranging from 1.67×10 –3 s −1 to 1×10 –1 s −1 . With proper deformation parameters, the Al–Mg–Sc–Zr alloy has an elongation to failure much higher than 300% and the maximum elongation is 740%. The Microstructure and dislocation substructure investigation using optical microscopy (OM) and transmission electron microscopy (TEM) revealed a dynamic recrystallization in it. The grain size and activation energy on the deformation mechanisms of superplastic is discussed. Results also show that these nano-scale Al 3 (Sc 1−x Zr x ) particles play an important role in the superplastic process. Al 6 FeMn particles were found to induce the formation and growth of cavities, which can lead to the fracture of specimens. [ABSTRACT FROM AUTHOR]

Extruded plates of 6005A aluminum alloy with 0.07 wt% Sc (referred to as M6005A alloy) was metal-inert-gas-welded (MIG-welded) with ER5087 filler wire. The microstructure, mechanical properties, and fatigue behavior of the joints were studied. Compared with the base material (BM), recrystallization occurred and the formation of the coarse β' phase was evident in the heat-affected zone close to the weld zone (HAZ 2), which resulted in a significant decrease in the mechanical properties of HAZ 2. However, trace Sc inhibited the growth of the recrystallized grains in the HAZ 2, strengthening the α-AlFeSi and β'′ phases in the BM, which drastically improved the mechanical properties of the BM. In the weld zone (WZ), grains were significantly refined since the presence of Al 3 (Sc, Zr) particles promoted the nucleation of such grains in the WZ, and the particles also promoted the non-uniform nucleation of the α-AlFeSi phase, which significantly improved the mechanical and fatigue properties of the WZ. The hardness distribution of the MIG-welded joint shows a double-W shape. The lowest hardness is 55 HV, observed in the HAZ 2. The ultimate tensile strength (UTS) and conditional fatigue strength (107 cycles) of the MIG-welded joint of M6005A-T6 are 238.5 MPa and 108.2 MPa, respectively, 38 MPa and 13 MPa higher than the those of the MIG-welded joint of 6005A-T6 alloy, respectively. • The 6005A alloy profile, with optimum content of Sc, was welded by MIG welding. • Study on microstructure and properties of welding joint of 6005A alloy containing Sc(referred to as M6005A-T6 alloy). • The mechanism of the effect of Sc on the structure and properties of 6005A welded joint was studied. • M6005A alloy is about to replace 6005A alloy as an important material for high-speed iron‑aluminum. [ABSTRACT FROM AUTHOR]

Mechanical property and corrosion resistance are essential performances in ultra-high strength Al-Zn-Mg-Cu alloys for the aerospace and weapon industries. In this study, the pre-strain and aging treatments were used to enhance such performances of the spray formed ultra-high strength Al-Zn-Mg-Cu alloy. After 2% pre-strain with peak aging (PA) and retrogression and re-aging (RRA) treatments, the ultimate tensile strength, yield strength, and elongation can reach to 774 MPa, 735 MPa, 10.7% and 774 MPa, 747 MPa, 9.4%, respectively. The coarser precipitates of the samples with 4% pre-strain can lead to the slight lower strength compared with the samples with 2% pre-strain. The proper combination of pre-strain and aging treatments can also effectively enhance the stress corrosion resistance of the studied alloy by the following reasons. First, the higher strain concentration degree and dislocation density introduced by pre-strain treatments have high internal energy and provide more stored energy for the growth of the passive film. Second, the spacing of grain boundary precipitates under double aging (DA) and RRA states is larger than that under PA state. The width of uniform precipitation free zone (PFZ) with 2% pre-strain is larger than that with 4% pre-strain. Third, after pre-strain treatments, the cracks perpendicular to the deformation direction can be produced in Al 7 Cu 2 Fe phase, which further breaks up such particles. According to the results of Kelvin probe microscopy, the Al 7 Cu 2 Fe phase with smaller dimension can obtain the lower difference of potential to Al matrix. • The strength and corrosion resistance of the alloy were enhanced by pre-strain. • The pre-strain produced cracks in Al 7 Cu 2 Fe particles and further broke up them. • The pre-strain improved the strain concentration degree and dislocation density. • The effect of precipitation free zone and precipitate is better under 2% strain. • The improvement mechanism of pre-strain treatment was revealed. [ABSTRACT FROM AUTHOR]

• Preparation of new-type Sc-containing 6005A aluminum alloy by ingot metallurgy. • The microstructure evolution, mechanical properties and fatigue behavior of 6005A alloy under different ageing are studied. • Established the aging system with the best anti-fatigue performance. A new type of alloy, modified based on 6005A alloy, with addition of 0.06% Sc was prepared by ingot metallurgy. The alloy ingots were homogenized, extruded, quenched and solution-aged into 8 mm thick plates. The effect of different aging treatments on the fatigue properties of 6005A alloy was investigated. It is revealed that optimum resistance against fatigue crack growth (FCG) was obtained in the under aged (UA) sample. The lowest fatigue crack growth rate (FCGR) was evident in the UA sample compared with the peak aged (PA) and over aged (OA) samples. [ABSTRACT FROM AUTHOR]

In the present work, laser shock peening was applied to the ultra-high strength Al-Zn-Mg-Cu alloys prepared by ingot metallurgy and spray forming. The microstructural evolution, pitting corrosion, intergranular corrosion resistance and electrochemical analysis were systematically investigated. The depth and number of corrosion pits caused by Al matrix, Al 7 Cu 2 Fe and Al 2 CuMg particles can be successfully reduced by laser shock peening. The depth of intergranular corrosion and the width of intergranular cracks also decreased. Cyclic polarization and electrochemical impedance spectroscopy tests also indicated the improved corrosion resistance caused by laser shock peening. The relationship between microstructural evolution and corrosion resistance was studied. • Corrosion resistance of ultra-high strength Al-Zn-Mg-Cu alloys is promoted by laser shock peening. • Al 2 CuMg and Al 7 Cu 2 Fe phases act as preferred sites for pitting corrosion. • Al 2 CuMg phase can cause deeper corrosion pits than Al 7 Cu 2 Fe phase. • Depth of pitting and intergranular corrosion are ameliorated by laser shock peening. • Residual compressive stress, line and surface defects is conducive to corrosion resistance. [ABSTRACT FROM AUTHOR]

2.5 mm thick cold-rolled Al–Zn–Mg–Zr alloy plates with trace amount of Sc were subjected to metal–inert gas (MIG) welding with Al–Mg–Sc as the filler metal. The influence of Sc additions on microstructure and mechanical properties of the welded joints was investigated by means of optical microscopy (OM), scanning electron microscope (SEM), energy dispersive X-ray (EDX), transmission electron microscopy (TEM), Vickers micro-hardness test and room temperature tensile test. Experimental results indicated that trace amount of Sc had significant effect on microstructure and mechanical properties of the joints. In both cases, base metal consisted of a typical fiber structure, different width of the equiaxed zones (EQZs) with fine grains were observed in the weld metal at the fusion boundary, fusion zones exhibited dendritic microstructure and average size of Al–Zn–Mg–0.10%Sc–Zr was 120 μm, while in Al–Zn–Mg–0.25%Sc–Zr, grain size decreased drastically to 50 μm. The grain refinement is mainly caused by the extremely fine, coherent Al 3 (Sc, Zr) particles with L1 2 structure, which act as heterogeneous nucleation. The observed grain refinement resulted in an appreciable increase in fusion zone strength and micro-hardness. Tensile strength of Al–Zn–Mg–0.25Sc–Zr alloy welded joint was 460 MPa, approximately 11% higher than Al–Zn–Mg–0.10Sc–Zr alloy welded joint. Micro-hardness in the center of fusion zone rose from 95 HV to 110 HV. The main strengthening mechanisms of Al–Zn–Mg–Sc–Zr MIG welded joints are precipitation strengthening derived from η′ precipitates, dispersion strengthening and fine grain strengthening caused by coherent secondary Al 3 (Sc, Zr) particles. [ABSTRACT FROM AUTHOR]

The precipitation behaviour, mechanical properties and corrosion performance of an Al-Zn-Mg-Sc-Zr alloy under one-stage aging (T6), two-stage aging (T74) and retrogression and re-aging (RRA) treatment were mainly investigated. For the RRA treatment, with increasing temperature and duration of retrogression, the grain interior precipitates (GIPs) gradually grew and changed from GP zones + η′ phases to η′ phases + η phases. In addition, the discontinuity of coarsened grain boundary precipitates (GBPs) significantly increased, and the width of precipitate free zones (PFZs) became broader. Consequently, progressive decrease in strength and hardness, and improved corrosion resistance of the alloy can be observed. Compared to conventional T6 and T74 treatments, a good balance of mechanical properties (168.5 HV for hardness, 547 MPa for ultimate tensile strength) and corrosion resistance can be obtained with retrogression treatment at 160 °C for 30 min. Moreover, research on the localized corrosion of the Al-Zn-Mg-Sc-Zr alloy showed that, at the initial stage of pitting corrosion, the Al matrix around the cathodic α-Al(Fe,Mn)Si particles was uniformly dissolved, leading to the detachment of the α-Al(Fe,Mn)Si particles from the matrix and the formation of pitting pits. • The strengthening and corrosion mechanisms of Al-Zn-Mg-Sc-Zr alloy under different aging conditions were studied. • A model for the process of pitting corrosion development is established. • The optimized RRA treatment for Al-Zn-Mg-Sc-Zr is obtained. [ABSTRACT FROM AUTHOR]

Highlights: [•] Anisotropy of fatigue growth rate is different from strength and toughness. [•] Fatigue behaviors are analyzed based on crystallographic model and Schmid factors. [•] Twist angle differences determine the intergranular or transgranular propagation. [•] Crack deflection and branch depend on slip systems and loading stress. [Copyright &y& Elsevier]

Highlights: [•] Investigate effect of aging temperature on corrosion behavior of an Al–Zn–Mg–Sc–Zr alloy. [•] Find the relationship between corrosion and microstructures of the studied alloy. [•] Corrosion behavior is determined using both electrochemical and immersion tests. [•] Improvement is due to absence of coarse precipitates and precipitate-free zones. [ABSTRACT FROM AUTHOR]

Highlights: [•] Hot deformation behavior of X-750 superalloy was investigated. [•] Processing maps were developed. [•] Flow instability regions identified and the mechanism was evaluated. [•] Optimum processing parameters were given. [ABSTRACT FROM AUTHOR]

Abstract: The flow behavior of Al–Zn–Mg–Sc–Zr alloy and its microstructural evolution during hot compression deformation were studied by thermal simulation tests. The tests were carried out in deformation temperature range from 340 to 500°C and at strain rate range from 0.001 to 10s−1. The results show that deformation temperature and strain rate have significant influence on the flow behavior of Al–Zn–Mg–Sc–Zr alloy. The flow stress increased with increasing strain rate, and decreased with increasing deformation temperature. In order to demonstrate the workability of Al–Zn–Mg–Sc–Zr alloy further, the processing maps at strain of 0.3 and 0.5 were established respectively based on dynamic materials model. The dynamic recrystallization of Al–Zn–Mg–Sc–Zr alloy occurred at deformation temperature of 420°C and a strain rate of 0.01s−1. At higher deformation temperature or lower strain rate, the grain size as well as the volume fraction of the recrystallized grains increased. At strain of 0.3 and 0.5, the flow instability domain mainly located at higher strain rate (>0.4s−1). On the basis of the processing map and microstructural evolution, the optimum processing conditions at a strain of 0.3 are in the strain rate range of around 0.001–0.1s−1 and deformation temperature range between 380 and 440°C. [Copyright &y& Elsevier]

Abstract: The behavior of the flow stress of Al–Cu–Mg–Ag heat-resistant aluminum alloys during hot compression deformation was studied by thermal simulation test. The temperature and the strain rate during hot compression were 340–500°C, 0.001s−1 to 10s−1, respectively. Constitutive equations and an artificial neural network (ANN) model were developed for the analysis and simulation of the flow behavior of the Al–Cu–Mg–Ag alloys. The inputs of the model are temperature, strain rate and strain. The output of the model is the flow stress. Comparison between constitutive equations and ANN results shows that ANN model has a better prediction power than the constitutive equations. [Copyright &y& Elsevier]

The effects of trace Sc and Y on the corrosion behaviors of cold-drawn Al-0.2Ce alloys were revealed by scanning Kelvin probe force microscopy (SKPFM), transmission electron microscopy (TEM), scanning electron microscopy (SEM), Electron Probe Micro-analyzer (EPMA), and electrochemical measurements. The results showed that the Al 3 Sc particles not only enable the increase of subgrain boundaries in the modified alloy after cold drawing but also improve the morphology and size of the Al 13 Fe 3 Ce phase. SKPFM analysis showed that the enrichment of Y around the Al 13 Fe 3 Ce phase in the modified alloy can decrease its electrochemical inertness and thus reduce the micro-galvanic corrosion susceptibility of the alloy. The results of the electrochemical analysis showed that the individual and composite addition of Sc and Y can improve the corrosion resistance of the cold-drawn Al-0.2Ce alloy. The corrosion potential and current of Al-0.2Ce-0.2Sc alloy are −0.892 V and 0.91 μA·cm−2, while the corrosion potential and current of Al-0.2Ce-0.1Y alloy are −0.918 V and 1.08 μA·cm−2, respectively. It is obvious that Sc element improves the corrosion resistance of Al-0.2Ce alloy more effectively than Y element. The corrosion depth of Al-0.2Ce-0.2Sc-0.1Y alloy was the smallest tested by immersion under the same conditions, and its corrosion potential and corrosion current were −0.842 V and 0.79 μA·cm−2, respectively, corresponding to the best corrosion resistance. The formal mechanism of pitting corrosion in the alloys is also discussed. [Display omitted] • Effect of Sc on microstructure and corrosion of Al-0.2Ce alloy was revealed. • The enrichment of Y atoms around Al 13 Fe 3 Ce can reduce the potential difference. • The corrosion behaviors of pitting corrosion induced by Al 13 Fe 3 Ce was discussed. • The equivalent circuit of the studied alloys was identified. [ABSTRACT FROM AUTHOR]

Sc-containing Al alloys have excellent mechanical properties, which provide the foundation for their applications. The precipitation of the Al 3 Sc/Al 3 (Sc, Zr) is generally considered to be a key factor for the performance boost. However, the performances of the alloy in different production batches often exhibit unstable and fluctuation, which may be related to the heterogeneous of scandium. Herein, we investigated the precipitation behaviors of Al 3 Sc/Al 3 (Sc, Zr) phases in the Al-0.5Sc and Al-0.5Sc-0.25Zr alloys at 340 °C. Results shown that the high scandium‑zirconium ratio not only lead to the discontinuous precipitation, but also contribute to the abnormal continuous Al 3 (Sc, Zr) precipitation in Al-0.5Sc-0.25Zr alloy. The morphology of abnormal Al 3 (Sc, Zr) is similar to the common secondary Al 3 (Sc, Zr) phase with a coffee-bean like morphology. With the aid of Three-Dimensional Atomic Probe (3DAP), the core-shell structures of Al 3 (Sc, Zr) phases are quantitatively analyzed. In the shell layer of abnormal Al 3 (Sc, Zr) phase, the atomic concentration ratio of Sc to Zr is much higher than the common continuous precipitated Al 3 (Sc, Zr) phase. The abnormal Al 3 (Sc, Zr) phase may be one of the key factors for the structure heredity of Sc-containing Al alloys. [Display omitted] • The discontinuous precipitated Al 3 Sc phases are related to the partial high ratio of Sc/Zr (at.%) in Al alloys. • The discontinuous precipitated Al 3 Sc phases form at the casting process and gradually decompose at annealing process. • The high scandium-zirconium ratio leads to the decrease of coarsening resistance of the secondary Al 3 (Sc, Zr) phase. [ABSTRACT FROM AUTHOR]

In ultra-high strength Al-Zn-Mg-Cu alloys, traditional heat treatments such as peak aging, two-stage aging and retrogression and re-aging cannot perfectly balance the relationship between mechanical properties and corrosion resistance and usually consume more time. Based on previous studies, the aim of this paper is to establish a suitable non-isothermal aging method for ultra-high strength Al-Zn-Mg-Cu alloys. In this study, after enhanced solution treatment and aging process with the heating rate of 20 °C/h, the alloy achieves excellent hardness and ultimate tensile strength of 195.7 HV and 680 MPA, respectively. When heating rate increases to 40 °C/h, non-isothermal aging can also ensure the alloy achieve the excellent mechanical properties (195.6 HV, 675 MPA). Similar to mechanical properties, the samples have outstanding resistance to intergranular and exfoliation corrosion, which is in accordance with the results of potentiodynamic polarization and electrochemical impedance spectroscopy tests. Evidences from high resolution transmission electron microscopy show that non-isothermal aging can promote the formation of a large number of smaller GP zones, η' precipitates and few η 2 precipitates inside grains, which greatly strengthens the mechanical properties. Furthermore, the grain boundaries precipitates transform from continuous to discontinuous and precipitate free zones form gradually, which greatly enhances the corrosion resistance. Because of these precipitates inside grains and grain boundaries, the samples with enhanced solution treatment +20 °C/h aging process and both solution treatments +40 °C/h aging process can achieve good mechanical properties closing to T6 state and corrosion resistance similar to T74 state simultaneously with much less aging time. Image 1 • The non-isothermal aging was designed as a novel route for heat treatments of ultra-high strength Al-Zn-Mg-Cu alloy. • An excellent combination of strength-ductility and corrosion resistance was achieved in the studied alloy. • The strengthening and corrosion mechanisms of non-isothermal aging on the studied alloy were discussed systematically. • Precipitation behavior of MgZn 2 strengthening phase was well studied. [ABSTRACT FROM AUTHOR]

The morphology of primary Al 3 Sc phase in Al-2.2Sc(wt%) was found to be influenced by melting condition. Some representative morphology appeared in large quantities at specific melting temperatures, holding times, and cooling rates. Crystallography of primary phases with various morphologies was researched, and the growth processes of the primary phase were investigated. Deformed cubes and dendrite can be developed from cubes, the butterfly-like particles had multiple layers inside, and repeated eutectic reactions were the main reason for the formation of multilayer structures. Al-2.2Sc(wt%) master alloys with different morphologies of primary Al 3 Sc phase can lead to different refining effects, and the mechanical properties of alloys were consequently influenced. The structure heredity of Al Sc master alloy was proved to be existed, and not influenced by prolonging insulation time and sufficient stirring. Unlabelled Image [ABSTRACT FROM AUTHOR]

The hot deformation behavior of Al-Mg-Si alloy is studied based on diffusion mechanism. The quantity of low angle grain boundaries increases rapidly, accompanied by the formation of subgrains and recrystallization grains with the increase of strain. Dynamic recovery (DRV) and continuous dynamic recrystallization (CDRX) are the main softening mechanisms, of which the DRV is dominant. The kinetics of dynamic recrystallization (DRX) represented by Avrami relationship shows that the DRX volume fraction increases with increasing strain. Physical-based diffusion constitutive model is established to demonstrate the flow behavior of the alloy. The relationship between diffusion activation energy and deformation condition is analyzed, and the dependence of creep exponent on temperature and strain is discussed. The result shows that the model describes the flow stress accurately. Lattice diffusion is the main diffusion mechanism during hot deformation. The variation of creep exponent can be reflected by dislocation density when the deformation mechanism is controlled by dislocation motion. Dynamic precipitation and the impediment of dislocation motion can lead to high value of creep exponent of the alloy. Unlabelled Image • Three types of physical-based diffusion models are established to demonstrate the flow behavior of the alloy. • The main diffusion mechanism during hot deformation is determined by constitutive analyses. • The relationships between creep exponent, diffusion activation energy and deformation condition are discussed. • The microstructure evolution and the dynamic softening mechanisms are investigated during hot deformation. [ABSTRACT FROM AUTHOR]

• Brass and S textures lead to larger Schmid's factor in the rolling direction (L–T). • FCG resistance in L–T was increased by atypical fibrous structure. • The cold-rolled-annealed samples show higher strengths and FCG resistance. • The alloy shows low anisotropy of FCG behavior in the Paris region. The fatigue crack growth characteristics of an Al-5.8Mg-0.25Sc(-0.4Mn-0.1Zr) alloy were investigated with regard to the loading direction. The cold-rolled and annealed samples show lower crack growth rates than hot-rolled samples at the same values of stress intensity factor (ΔK). The rolling (L–T) and transverse (T–L) directions exhibit different fatigue crack growth rates at the initial stage and unstable stage, but present similar behavior in the Paris stage. Results reveal that the Brass and S textures in Al-5.8Mg-0.25Sc alloy can lead to larger Schmid's factor and higher resolved shear stress in the rolling direction than in the transverse direction when the same value of stress is applied to the alloy, so the strength in the rolling direction is relatively lower and the fatigue crack growth rate of it is relatively higher in the initial stage. While the resistance to fatigue crack growth in the rolling direction was also increased by an atypical fibrous structure, consequently, the balance between the resolved shear stress and the resistance against fatigue crack growth related to the alloy orientation results in a unique anisotropy of fatigue crack growth behavior of Al-5.8Mg-0.25Sc alloy in the Paris region. [ABSTRACT FROM AUTHOR]

The quench sensitivity of Al–Mg–Si–Mn–Cr alloy was studied through time-temperature-transformation (TTT) and time-temperature-property (TTP) curves. The high quench sensitive region ranges from 250 °C to 430 °C with nose temperature at about 350 °C, where the quenching rate is required to higher than 9 °C/s for avoiding the formation of quench-induced precipitates. B′(Al 3 Mg 9 Si 7) precipitates from the supersaturated solid solution, and gradually transforms to equilibrium β (Mg 2 Si) and excess Si phase with increasing isothermal time at 350 °C. The loss of the solute atoms in matrix results in the reduction of the aging hardening precipitation and the formation of the precipitate-free zones (PFZs) during artificial aging. The nucleation rate of the quench-induced precipitation is studied by nucleation theory, and the phase transformation kinetics is analyzed through Avrami equation. The Al(MnCrFe)Si dispersoids, (sub)grain boundaries and dislocations are the preferential heterogeneous nucleation sites for quench-induced precipitation. • The quench sensitivity of the alloy was studied by time-temperature-transformation and time-temperature-property curves. • The microstructure evolution of the quench-induced precipitate and its effect on mechanical properties were analyzed. • The nucleation rate and phase transformation kinetics of the precipitation were investigated. • The preferential heterogeneous nucleation site for quench-induced precipitation was discussed. [ABSTRACT FROM AUTHOR]