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Herein, the influence of equal channel angular pressing (ECAP) routes, i.e., A and Bc, on the microstructure and texture evolution of a Mg–3.7Al–0.7Zn–0.8Sn–0.4Mn (wt%) alloy is investigated by scanning electron microscopy (SEM), electron backscatter diffraction (EBSD), and X‐ray diffraction (XRD). It is found that with increasing the number of ECAP passes, the area fraction of the dynamically precipitated secondary‐phase particles increases, whereas particle size becomes larger. After four and six passes of ECAP via route A, shear deformation induced by ECAP promotes the incline of c‐axes toward extrusion direction (ED). The optimum room temperature (RT) mechanical properties (yield strength of ≈225 MPa, ultimate tensile strength of ≈312 MPa, and elongation to fracture of ≈31.9%) are obtained after four passes of ECAP at 200 °C via route A. The improved strength results from fine dynamic recrystallization (DRX)/ed grains, nanoscale secondary‐phase particles, and basal texture. Herein, it is indicated that Mg–Al–Zn–Sn alloys have great potential as low‐cost high‐strength‐ductility wrought Mg alloys. [ABSTRACT FROM AUTHOR]

Effects of Zn addition on the microstructure and tensile properties of as-extruded Mg-8Al-2Sn (AT82) alloy were investigated in the present work. All the extruded AT82 alloys exhibited a fully dynamically recrystallized (DRXed) microstructure, while the grains were slightly refined with Zn addition. Moreover, second phase particles (Mg 2 Sn and Mg 17 Al 12 ) increased significantly in amount with increasing Zn content. It was found the ultimate tensile strength (UTS) and yield strength (YS) gradually increased with increasing Zn content from 0 to 1.5 wt%, meanwhile the elongation maintained unchanged at a high level, i.e. ~17–19%. In particular, the as-extruded AT82-1.0Zn alloy exhibited both a high strength and high ductility at room temperature, e.g. UTS of ~357 MPa and elongation of ~19%. The superior combination of strength and ductility is mainly benefited from the enhanced work-hardening ability resulted from Zn solid solutes and the presence of more well-dispersed fine particles in AT82-1.0Zn alloy. [ABSTRACT FROM AUTHOR]

In the present study, Mg-6Zn-1Zr (ZK60) alloy with a homogeneous fine-grained structure (~5 µm) was produced by hot extrusion. The influence of temperature on tensile properties anisotropy and the associated change in deformation mechanisms in the range of 25–275 °C of the fine-grained ZK60 alloy were investigated. Under room temperature, the fine-grained ZK60 alloy exhibited a high tensile strength of ~269–327 MPa and high ductility of ~15–39% when tested at three different directions, indicating a high anisotropy. With increasing testing temperature to 150 °C and further to 275 °C, the alloy showed a gradual decrease in anisotropy. Especially, the fine-grained ZK60 alloy exhibited superplasticity of ~376–434% when tested at 275 °C, which should be due to the increasing role of grain boundary sliding (GBS), as the strong basal texture associated with room temperature deformation became almost random at elevated temperatures. Moreover, the abrupt decrease in tensile anisotropy and associated change in texture with increasing temperature correlates closely to the transformation of deformation mode from a dislocation-dominated behavior to a GBS-mediated one. [ABSTRACT FROM AUTHOR]

The morphology evolution of primary Mg 2 Si particles in a Al-20Mg 2 Si-4.5Cu alloy both unmodified and modified with 0.5 wt% Ca-Sb prepared by hot-extrusion followed by T6 heat treatment was investigated in the present study. Interestingly, we found that the combination of hot-extrusion and T6 heat treatment was efficient in transforming truncated octahedral primary Mg 2 Si into sphere in the modified alloy. In contrast, the primary Mg 2 Si particles still kept dentritic in the unmodified alloy. It suggested that the formation of truncated octahedral primary Mg 2 Si particles in as-cast state, the fragmentation of particles by hot-extrusion and the enhanced solid-state diffusion of Si and/or Mg atoms during heat treatment were responsible for the spheroidization of primary Mg 2 Si. Moreover, the existence of fine (~10–20 µm) spherical primary Mg 2 Si played an important role in strengthening the alloy, i.e., the ultimate tensile strength (UTS) increased from ~227 MPa in the unmodified alloy to ~303 MPa in the modified one. It is because the fine spherical primary Mg 2 Si particles can provide a higher fracture stress and strength of the matrix/particle interface. Our study offered a simple methodology to prepare spherical primary Mg 2 Si in an Al-high Mg 2 Si alloy, which is beneficial to design novel light-weight Al-Mg-Si alloys with improved mechanical properties. [ABSTRACT FROM AUTHOR]

Cast-rolling AZ31 Mg alloy sheets were manufactured at four rolling speed ratios of 0.8, 1.0, 1.2 and 1.3. The results show that the basal texture can be weakened by differential speed rolling (DSR). The AZ31 alloy sheet manufactured at a speed ratio of 1.2 exhibits a fine microstructure with an average grain size of 10.3 μm. The yield strength, ultimate tensile strength and elongation-to-failure at this speed ratio are 145 MPa, 240 MPa and 28.5% at room temperature, respectively. These parameters mainly benefit from the fine grains and weakened basal texture. The AZ31 alloy sheets processed by the DSR exhibit a remarkable improvement in elongation-to-failure compared with the AZ31 alloy sheets processed by equal speed rolling (ESR) primarily due to the weakened basal texture at room temperature. However, the difference in elongation-to-failure of the AZ31 alloy sheets processed by the ESR and DSR decreases at elevated temperatures, which can be attributed to the weakening of the influence of basal texture, with probable activation of non-basal slips and grain boundary sliding (GBS). The results obtained here will shed light on some DSR methods, which is critical to the development of Mg alloys with high mechanical properties. [ABSTRACT FROM AUTHOR]

A sandwich structure laminate composed of a ductile 2014Al inter-layer and two nanoscale SiC reinforced 2014Al (SiC/2014Al) composite outer layers was successfully fabricated through the combination of powder metallurgy and hot rolling. The ductile 2014Al inter-layer effectively improved the processability of the sandwiched laminates. Tensile test revealed that the yield strength and ultimate tensile strength of the sandwiched laminate were 287 and 470 MPa, respectively, compared with 235 and 425 MPa for monolithic 2014Al. The good performance of the sandwiched laminate results from the strong bonding between the SiC/2014Al composites layer and the ductile 2014Al layer. Thus, the sandwich structure with a composite surface and ductile core is effective for increasing the strength and toughness of composite laminates. [ABSTRACT FROM AUTHOR]

Nano-SiC particulates (n-SiC) reinforced Mg-8Al-1Sn (AT81) composites with different volume fractions (0, 0.25, 0.5 and 1.0 vol.%) were fabricated by powder metallurgy process (P/M) combined with hot extrusion. The mechanical properties of the composite increased as the n-SiC content increased until the n-SiC content exceeded 0.5 vol.%, at which point they began to decrease. For this reason, the 0.5 vol.% n-SiC/AT81 composite was considered optimal. The 0.2% offset yield strength (YS), ultimate tensile strength (UTS) and elongation (ε) of 0.5 vol.% n-SiC/AT81 composites increased from 175, 318 MPa and 4.5% to 239, 381 MPa and 8.3%, respectively, compared to AT81. Both, the strength and plasticity of the 0.5 vol.% n-SiC/AT81 composites were improved as well. The improvement in mechanical properties can be attributed to the progressively refined matrix grain size, relatively uniform distribution of n-SiC and the well-bonded interfaces between n-SiC and the matrix. [ABSTRACT FROM AUTHOR]

This work was carried out to investigate the relationship between microstructures and mechanical properties of extruded Al–20Mg 2 Si–4Cu alloys unmodified and modified with 0.5 wt% Sb addition at room and high temperatures. Various techniques including metallography, field emission scanning electron microscope, differential thermal analysis and scanning electron microscopy were used to characterize the microstructure, tensile behavior and fracture mechanism of the alloys. It was found that 0.5 wt% Sb additions were highly effective in refining microstructures by changing the morphology of primary Mg 2 Si from coarse dendrite into smaller polyhedral shape with average size less than 20 µm. Tensile test showed that ultimate tensile strength (UTS) of the modified alloy increased dramatically to 283 MPa at room temperature and 213 MPa at 150 °C, evidently higher than the 220 MPa and 185 MPa for the unmodified alloy, respectively. Fracture surface examinations revealed a transition from particle fracture of primary Mg 2 Si in the unmodified alloy to particle–matrix interface debonding in the modified alloy. The transformation of primary Mg 2 Si from coarse dendrites to refined polygonal shapes contributes to the enhanced strength and ductility of the modified alloy, since the polygonal primary Mg 2 Si particles dispersed uniformly in modified alloy, impeding dislocation motions and freeing stress concentrations. A schematic map was established to further elucidate the mechanisms of fracture behavior during stretching process. [ABSTRACT FROM AUTHOR]

Abstract: Mg–5Sn alloy are successfully fabricated by a horizontal centrifugal casting method. Developed columnar dendritic crystals under the gravity casting condition can be mostly transformed into fine equiaxed grains by the centrifugal casting. Compared with the gravity casting, compression strength, yield strength and elongation-to-failure are significantly improved by the centrifugal casting, which increase from 181.6 to 257.5MPa, 38.7 to 52.3MPa and 14.9% to 21.2% on position r 1 (centrifugal radius r 1=0.05m), respectively. Moreover, the centrifugal casting also enhances work-hardening ability of the alloy. The transformation of crystals results in the enhancement of the compression properties and work-hardening ability. The results obtained here will shed some light on special casting methods of Mg alloys, which is potential to develop new light alloys with high strength and elongation. [Copyright &y& Elsevier]

Highlights: [•] As Al or Zn contents increase, GSF energies of Mg-Al-Zn solid solution decrease. [•] As Al or Zn contents increase, more locations with low GSF energy emerge. [•] Al and Zn dopings decrease GSF energy by softening Mg–Mg of slip planes. [•] Reduced GSF energy promotes activation of non-basal slip and enhances plasticity. [•] Criterion for predicting the most probable location for planar defect is proposed. [Copyright &y& Elsevier]

Abstract: As-cast Mg–3Al–3Sn (AT33) alloy exhibits strong strain hardening ability, which is illustrated by the very high H c and n values. Decrease in generalized stacking fault (GSF) energies in AT33 alloys by Al and Sn additions facilitates the production of dislocations and activation of deformation twins, causing the accumulation of dislocations at twin boundaries, resulting in a high dislocation density in deformed alloys during tension deformation, which thereby mainly accounts for the strong strain hardening ability. [Copyright &y& Elsevier]

The microstructure, mechanical properties and corrosion behavior of hot–rolled Mg–xSn–1Zn–0.5Ca (x = 1, 3 and 5 wt.%) alloys were investigated for possible application as biodegradable implants. The hot–rolled Mg–xSn–1Zn–0.5Ca alloys consisted of α-Mg matrix and Mg2Sn phase. The number of the Mg2Sn particles significantly increased and the grains were gradually refined (14.2 ± 1.5, ~10.7 ± 0.7 and ~6.6 ± 1.1 μm), while the recrystallized fraction significantly decreased with the increase in the Sn content, the Mg–1Sn–1Zn–0.5Ca alloy was almost completely recrystallized. Ultimate tensile strength (UTS) and tensile yield strength (TYS) increased slightly, reaching maximum values of 247 MPa and 116 MPa, respectively, for the Mg–5Sn–1Zn–0.5Ca alloy, and the elongation decreased with the increase in the Sn content; the Mg–1Sn–1Zn–0.5Ca alloy showed the highest elongation (15.3%). In addition, immersion tests and electrochemical measurements in Hank's solution revealed that the corrosion rates of Mg–xSn–1Zn–0.5Ca alloys increased with the increase in the Sn content. A model of the corrosion behavior was discussed for hot–rolled Mg–xSn–1Zn–0.5Ca alloys in Hank's solution. Among the Mg–xSn–1Zn–0.5Ca (x = 1, 3 and 5 wt.%) alloys, Mg–1Sn–1Zn–0.5Ca alloy exhibits optimal corrosion resistance and appropriate mechanical properties. [ABSTRACT FROM AUTHOR]

Three Al- x Mg- y Zn-1Cu alloys with equal total alloying element contents but different Mg/Zn ratios have been prepared in this work, i.e., Al–6Mg–1Zn–1Cu, Al–5Mg–2Zn–1Cu and Al–4Mg–3Zn–1Cu alloys. The influences of Mg/Zn ratios on microstructure and mechanical properties of heat-treated Al- x Mg- y Zn-1Cu alloys have been systematically studied. The results show that Al- x Mg- y Zn-1Cu alloys with higher Zn contents exhibit the faster aging response as Zn atom features the largest diffusion coefficient. Additionally, rod shaped and ellipsoidal T′ precipitates are observed in the Al–6Mg–1Zn–1Cu alloy. While in Al–4Mg–3Zn–1Cu alloy under TMT-2 process, T′ precipitates mainly exist in an ellipsoidal shape, with a higher number density (∼1.79 × 1023 m-3) and smaller size (∼4.1 nm) compared to the Al–6Mg–1Zn–1Cu alloy. The optimized thermomechanical treatment (80 °C/5 h + rolling + 130 °C/ x h) could effectively improve the yield strength of Al–5Mg–2Zn–1Cu and Al–4Mg–3Zn–1Cu alloys, with values increasing from ∼419 MPa to ∼441 MPa–∼454 MPa and ∼470 MPa, respectively. In contrast, the Al–6Mg–1Zn–1Cu alloy exhibit almost no increment in yield strength after the same thermomechanical treatment. This could mainly be attributed to the higher density of T′ precipitates in alloys with higher Zn contents, resulting from the higher nucleation rate of T′ precipitates caused by high contents of Zn atoms featuring fast diffusion rates, with the assistance of dislocations introduced by rolling. This work provides theoretical supports for the development and production of age-hardenable Al- x Mg- y Zn-1Cu alloys. [ABSTRACT FROM AUTHOR]

Al–8Si-0.5 Mg, Al–8Si–2Cu, and Al–8Si–2Cu-0.5 Mg alloys have been designed in this study, aiming to reveal the influence of Mg and/or Cu additions on microstructures and mechanical properties of Al–Si alloys. Transmission electron microscopy (TEM), differential scanning calorimetry (DSC) and the Kampman-Wagner Numerical (KWN) model have been used to investigate age-hardening behaviors as well as their relation to mechanical properties. Microstructure analysis suggest that β'', θ′ and QP precipitates have formed in peak-aged Al–8Si-0.5 Mg, Al–8Si–2Cu and Al–8Si–2Cu-0.5 Mg alloys, respectively. Notably, the Al–8Si–2Cu-0.5 Mg alloy exhibits faster precipitation kinetics, larger age-hardening response and remarkable thermal stability compared to the other two alloys. Theoretical calculations indicate that the nucleation of QP precipitates is easier than β'' and θ′ precipitates, but the slower diffusivity of Cu limits the growth rate of QP precipitates during the growth stage. Furthermore, the contribution of β'', θ′ and QP precipitates to yield strength of peak-aged Al–Si alloys has been quantified, which shows a significant variation. β'' precipitates in the Al–8Si-0.5 Mg alloy exhibit the highest strengthening effect (∼186.4 MPa), followed by QP precipitates in Al–8Si–2Cu-0.5 Mg (∼160.2 MPa) and θ′ precipitates in the Al–8Si–2Cu alloy (∼13.4 MPa). This work provides valuable insights into the influence of Mg and/or Cu additions on the aging response and mechanical properties of Al–Si alloys, offering a reference for further enhancing the performance of Al–Si alloys. [ABSTRACT FROM AUTHOR]

The design of Al-Mg-Si-Zn series alloys combines the advantages of 6xxx and 7xxx series alloys and breaks through the limitations of strength and formability matching of traditional alloys. In this study, we achieved an exceptional strength-formability combination in the Al-0.84Mg-0.79Si-3.38Zn (wt.%) alloy. Following a solution treatment at 550 °C for 3 min, the alloy exhibited an elongation of ∼36.8%, with a yield strength of ∼356 MPa after artificial aging at 175 °C for 8 h. The effects of different Mg/Si ratios (∼0.6, ∼1.2, and ∼2.5, at.%) on the strength-formability interplay in Al-Mg-Si-Zn alloys were investigated. The alloy with a low Mg/Si ratio (∼0.6) facilitated the precipitation of fine β'' phases characterized by a high number density (∼8.4 nm−3 × 10−5). A Mg/Si ratio of ∼1.2 proved advantageous for precipitating larger β'' phases with a higher volume fraction (∼0.69%), resulting in an elevated precipitation strengthening effect (∼290 MPa). However, with an increase in the Mg/Si ratio to ∼2.5, the reduced availability of Si atoms for forming Mg-Si clusters led to a decrease in the number density of precipitates. Additionally, the interaction among Fe, Mn, and Si elements resulted in the presence of blocky α-Al(FeMn)Si phases, as opposed to the needle-like β-AlFeSi phases, in the alloy with a Mg/Si ratio of ∼1.2. This effectively prevented the degradation of elongation. Our findings present a comprehensive strategy for the compositional design of high-performance aluminum alloys. • The effects of different Mg/Si ratios on the strength-formability interplay were investigated. • The alloy with a Mg/Si ratio of ∼1.2 exhibits an exceptional strength-formability combination. • The mechanism of high strength and high formability was revealed. [ABSTRACT FROM AUTHOR]

In this work, the synergistic effect of pre-aging and pre-straining on the enhanced age-hardening response of an Al–5Mg–2Zn–1Cu alloy has been systematically investigated using high-resolution transmission electron microscopy (HRTEM) and atom probe tomography (APT). After pre-aging, only Guinier Preston (GP) zones uniformly distribute in the α-Al matrix. Moreover, dislocations induced by pre-straining can promote the nucleation and growth of T″ and T′ precipitates. With the synergy of pre-aging (80 °C/5 h) and pre-straining (∼4%) treatments, the alloy after second-aging at 130 °C for 12 h exhibits a giant increase of yield strength (∼182 MPa) in comparison to the as-solutionized alloy, reaching ∼348 MPa. The above results show that pre-aging and pre-straining are effective in accelerating the hardening response of Al–Mg–Zn–Cu alloys. Especially, this extraordinary age-hardening response depends strongly on the high number density and uniform distribution of the GP zones induced by pre-straining, acting as preferential nucleation sites for T″ phase and T′ phases during subsequent aging treatment. In addition, it proves that pre-aging and pre-straining can effectively control the precipitation free zones (PFZs) size, relieving the strain concentration in PFZs and improving the comprehensive mechanical properties. [ABSTRACT FROM AUTHOR]

• A bimodal-grained WE43 alloy consisting of fine grains (FGs) and coarse grains (CGs) with superior strength-ductility synergy has been achieved by one pass rolling. • Statistical slip trace analysis reveals that the deformation behaviors of FGs and CGs are quite different, i.e., basal slips are dominate in FGs while non-basal slips are prevalent in CGs. • Multi-faceted equilibrium β phase has precipitated along grain boundaries of FGs, while short rod-shaped metastable β 1 phase has formed within CGs. • Interactions between pyramidal dislocations and β 1 precipitates dominant the Orowan strengthening. • The stress concentration near grain boundaries can be released by activating plenty of non-basal slips in CGs and slip transfers between FGs, preventing effectively the premature failure and leading to enhanced ductility. Achieving a high strength-ductility synergy in rolled Mg alloys remains a major challenge, especially for Mg alloys with high contents of rare earth (RE) elements, which are hard-to-deform and exhibit poor formability. In the present work, a bimodal grain structure consisting of fine grains (FGs) and coarse grains (CGs) has been achieved in a novel WE43 alloy sheet prepared by the hard-plate rolling (HPR) technique, which breaks the strength-ductility trade-off dilemma of the conventional WE43 alloy. Notably, the yield strength (YS) reaches as high as ∼312 MPa, presenting a remarkable improvement of YS (∼60 MPa) in comparison to conventionally rolled counterparts. Meanwhile, the ultimate tensile strength (UTS) and elongation-to-failure (EF) are ∼332 MPa and ∼11.8%, respectively, much higher than those of the wrought WE43 alloy reported in literature. Specifically, the disparate dislocation slips and dynamic precipitation behaviors in FGs and CGs have been studied in detail by combining EBSD and TEM analysis. The discrepancy of dynamic precipitation behavior in FGs and CGs is originated from the heterogeneous dislocation slip-dominated deformation behavior during HPR, related to initial grain orientations. It reveals that basal slips are dominant in the FG area, where equilibrium β-Mg 14 Nd 2 Y phase has precipitated along grain boundaries. In contrast, non-basal slips are prevalent and the metastable short rod-shaped β 1 phase has formed within CGs. The enhanced YS of the present HPRed WE43 alloy sheet is mainly attributed to the formation of large amounts of extremely fine grains with an average size of ∼0.94 μm. The enhanced Orowan strengthening comes from the interaction between short rod-shaped β 1 particles and non-basal dislocations (prismatic , pyramidal and pyramidal dislocations) in CGs. In particular, the interactions between β 1 particles and pyramidal dislocations dominate the Orowan strengthening, leading to an increase of ∼34 MPa in the YS. Basal to basal slip transfers have been observed in FGs while non-basal slips are prevalent in CGs, which could be helpful for release the stress concentration near GBs. It is beneficial for preventing earlier fracture and thus enhancing the tensile strength combined with decent ductility. [Display omitted] [ABSTRACT FROM AUTHOR]

The long-term thermal stability of Al–Mg–Si alloy is of great significance for its engineering application. In this work, the effects of Mn and Cu on the microstructure and mechanical properties of the twin-roll cast (TRC) AA6005 alloy after peak aging and long-term thermal exposure were studied. The results show that the addition of Mn introduces Al(FeMn)Si dispersoids, which improves the mechanical properties of the alloy under the peak aging condition by dispersion strengthening. After thermal exposure at 150 °C for 1000 h, the Al(FeMn)Si dispersoids have good thermal stability while do not significantly improve the mechanical properties. The reason may be related to the decreased number density of the β″ phase after alloying with Mn. The addition of Cu changes the aging precipitation sequence, and the needle-like pre-Q′ phase is formed during artificial aging. Moreover, due to the low diffusion rate of Cu in the Al matrix, Cu atoms can better stabilize the structure and then improve the coarsening resistance of the precipitates, and therefore the Cu-containing precipitates exhibit better thermal stability than the β″ phase. After thermal exposure at 150 °C for 1000 h, the yield strength of the 0.5Cu alloy decreases by only ∼12 MPa (from ∼295 to ∼283 MPa), which is significantly lower than that of the AA6005 alloy (∼41 MPa, from ∼274 to ∼233 MPa). The yield strength of the 0.25Mn0.25Cu alloy decreases by ∼27 MPa (from ∼294 to ∼267 MPa) and is more suitable for industrial production as its composition is within the range of commercial 6xxx aluminum alloys. The results would provide a strategy for the preparation of Al–Mg–Si alloys with high thermal stability. [ABSTRACT FROM AUTHOR]

Dissolving the inherent central segregation is critical to improve the performance of twin-roll casting (TRC) aluminum strips. In this study, we investigated the effects of Cu content (0.8, 1.2, and 1.6 wt%) on the central-segregation composition and mechanical properties of TRC Al–0.8Mg–1.0Si alloys. Cu promoted the segregation-phase transformation from the higher-melting-temperature Mg 2 Si phase to the lower-melting-temperature Cu-containing phases (Q -AlCuMgSi and θ -Al 2 Cu), resulting in an easier dissolution of central segregation. Therefore, the segregation of 0.8 and 1.2 wt% Cu alloys was almost dissolved following cold rolling and solution treatment compared to Cu-free alloys. However, after a higher content of Cu (1.6 wt%) was added, the segregation became too severe to dissolve. After modifying with 1.2 wt% Cu, the yield strength (YS) of the TRC alloy increased from ∼306 to 335 MPa, and the elongation was increased from ∼13 to 17%. The contribution of solution strengthening and increasing volume fraction of precipitates results in the strengthening effect of Cu. Meanwhile, the dissolution of segregated phases is also advantageous for solution and precipitation strengthening. This study could lead to the development of a simple method to dissolve TRC central segregation and produce TRC Al–Mg–Si alloys with excellent performance. [ABSTRACT FROM AUTHOR]

The effect of quenching rates after solid solution treatment, i.e., water-quenching (WQ) and wind-cooling (WC) on the precipitation behavior during subsequent artificial aging and mechanical properties of aged Al-Si-Cu-Mg alloys at room temperature and 150 °C–300 °C have been investigated. Compared with the peak-aged WC alloy, the number density of precipitates in the peak-aged WQ alloy is higher. After further holding at 300 °C for 10 min, plenty of metastable Q', θ' and β'' phases have transformed into equilibrium phases (Q, θ and β), with some also dissolved. However, the number density of precipitates in the peak-aged WQ alloy with holding at 300 °C for 10 min is relatively higher. The results demonstrate that the age hardening response rate and peak hardness of the WQ alloy during aging are much higher. At room temperature, the peak-aged WQ alloy owns a higher yield strength (YS) of ∼324 MPa than that of the peak-aged WC alloy (∼301 MPa), which can be attributed to the enhanced precipitation of Q' and θ' phases. The ultimate tensile strength (UTS) and YS decrease as the tensile temperature increases. However, the strength of the water-quenched alloy is higher than that of the wind-cooled alloy, due to the retention of more precipitated phases. • The effect of quenching rates after solid solution treatment has been studied. • Quench-induced Q' and β" phases lead to higher hardness of the WC alloy. • The enhanced precipitation in the peak-aged WQ alloy results in a higher YS. • Quantitative analysis suggest that the enhanced YS is mainly attributed to Q' phase. [ABSTRACT FROM AUTHOR]

Regulating the solute atoms to form dense nano-sized precipitates is an essential strategy to enhance the strength of Mg alloys, wherein the maximum strength improvement is usually achieved by artificial aging at low temperatures (150-250 °C) for several to dozens of hours. In the present study, we found that a Mg-1.04Zn-0.52Ca-0.27Sn-0.18Mn (wt.%, ZXTM1100) alloy exhibits a substantial yield strength (YS) increment of ∼81 MPa after undergoing cyclic deformation (CD) at room temperature. Moreover, the impressive YS improvement only reduces the elongation to failure from ∼18% to ∼16%. To explore the strengthening mechanisms, the microstructure evolutions of cyclically deformed ZXTM1100 alloy have been systematically investigated by multi-length scale characterization techniques, including synchrotron X-ray diffraction, transmission electron microscopy (TEM), and correlative transmission electron microscopy and atom probe tomography (TEM-APT). It has been found that the strength increment mainly originates from the dynamic formation of a high density (∼5.7 × 1024 m-3) of multi-type solute clusters (e.g. Zn-Ca, Zn-Ca-Mn, and Zn-Zn), which can strengthen the alloy by ∼70 MPa. For the first time, such a high strengthening effect from the formation of solute clusters has been reported in a dilute Mg alloy. The accelerated solute clustering process can be rationalized when considering the supersaturated non-equilibrium vacancies produced by CD treatment. Our work not only demonstrates the pronounced cluster strengthening effect in a dilute Mg alloy, but also could provide new insights into the development of Mg alloys with high strength-ductility synergy. [Display omitted] [ABSTRACT FROM AUTHOR]

Achieving dense coherent precipitates in 7xxx aluminum alloys during artificial aging to attain high strength-ductility synergy remains a challenging task as they are unstable and tend to dissolve or transform to the semi-coherent phase. Here, we successfully obtained high-density (1.32 × 1024 m−3) and fine-sized (∼4.1 nm) coherent precipitates in the twin-roll cast Al-6.3Zn-3.3Mg-1.8Cu (wt.%) alloys through pre-strain and subsequent artificial aging, i.e. strain aging. Therefore, the peak-aged sample exhibited a satisfactory tensile strength of ∼600 MPa and extraordinary fracture elongation of ∼15%. The inconspicuous interface between coherent precipitates and the Al matrix reduces the tendency of interfacial stress concentration, which ensures high room temperature ductility. The strengthening mechanism was calculated by the dislocation shearing model, indicating that coherent precipitates contribute ∼80% of the total yield strength. This work could provide a short-process and low-budget method for preparing high-performance 7xxx series alloy strips. • High strength-ductility synergy was achieved in twin-roll cast Al–Zn–Mg–Cu alloys. • The center segregation can be eliminated by rolling and heat treatment. • High-density coherent precipitates were obtain in peak-aged Al–Zn–Mg–Cu alloys. • Coherent precipitates were mediated by enhancing solubility and crystal defects. • The strengthening mechanism of peak-aged samples was calculated and analyzed. [ABSTRACT FROM AUTHOR]

The (micron+nano) bimodal sized SiC p /Al2014 composites fabricated by semi-solid stirring exhibited fine α-Al grains, well-dispersed bimodal sized SiC p and well-bonded interface between SiC p and matrix. The yield and ultimate tensile strength of the extruded bimodal sized SiC p /Al2014 composites were significantly enhanced, compared to the extruded single-sized SiC p /Al2014 composites. [ABSTRACT FROM AUTHOR]

The existence of coarse Fe-bearing phases and macro-segregation under the twin-roll casting (TRC) condition has always been a restrictive factor for the preparation of high-performance Al alloys. In this work, the effect of Mn contents on the formation of Fe-bearing phases, macro-segregation behavior and mechanical properties of TRC Al-0.5Mg-0.7Si-0.1Fe- x Mn (x = 0, 0.1, 0.3 and 0.5 wt.%) alloys have been investigated. The macro-segregation region in the as-cast 0Mn alloy is found to contain coarse secondary phases consisting of Al, Fe, Mg and Si. In as-cast 0.1Mn and 0.3Mn alloys, macro-segregation has been alleviated due to the transformation of π-AlFeMgSi phase to α-Al(FeMn)Si phase, as a result of the inhibited peritectic reaction to form the π-AlFeMgSi phase by the addition of Mn. However, with further increasing the amount of Mn, coarse intermetallic compounds at the center region tend to form in the 0.5Mn alloy, which aggravates macro-segregation again. The 0.1Mn alloy exhibits a better combination of yield strength (287 MPa) and elongation (18.9%) than that of the 0Mn alloy (274 MPa, 15.9%) under the artificial aging condition. The higher yield strength of the 0.1Mn alloy is mainly due to the formation of fine α-Al(FeMn)Si particles that make a strong contribution to dispersion strengthening. This work provides a reference for weakening macro-segregation via regulating Fe-bearing phases, which is of great importance in developing AA6xxx series TRC alloys with high performance. [ABSTRACT FROM AUTHOR]

The composition and morphology of the Fe-bearing phase play a significant role in the mechanical properties of aluminum (Al) alloy sheets. In this work, we have studied the formation of Fe-bearing phases in an Al-0.53Mg-0.69Si-0.14Fe (wt%) alloy under the twin-roll casting (TRC) and the direct chill casting (DC) processes, respectively. We found that the π-AlFeMgSi phase was formed in the as-cast TRC sample, while the β-AlFeSi phase was formed in the as-cast DC sample. The differences in the formation of Fe-bearing phases are attributed to the promotion of the peritectic reaction to form the π-AlFeMgSi phase via the TRC process. Furthermore, after homogenization treatment at 550 °C and 2 h, the π-AlFeMgSi phase in the as-cast TRC sample completely decomposed into the fine β-AlFeSi phase, while it was insufficient to dissolve the β-AlFeSi phase in the as-cast DC sample. This is owing to the lower dissolution temperature of the π-AlFeMgSi phase compared to the β-AlFeSi phase. The decomposition of the π-AlFeMgSi phase expands the solid solubility and promotes the aging precipitation, resulting in higher yield strength of the TRC sample than that of the DC sample during the peak-aging treatment. Our work provides new insight into the development of high-performance AA6xxx series alloys based on the TRC process. ● The π-AlFeMgSi phase was found in the as-cast twin-roll casting (TRC) sample. ● The homogenization treatment of 550 °C -2 h can make the π-AlFeMgSi phase dissolved. ● The mechanism of TRC phase formation was revealed. ● Microstructure and tensile properties of TRC AA6005 aluminum sheet were studied. [ABSTRACT FROM AUTHOR]

Texture weakening is generally adopted as one of the prominent methods to improve the ductility of Mg alloys. In this work, we designed and fabricated the Mg-1Zn-1Sn-0.3Y-0.2Ca (wt. % ZTWX1100) alloy with a novel basal-random heterogeneous (BRH) texture by precisely controlled high-reduction rolling, which contained both basal- and random-oriented grains with a uniform distribution. Compared with the basal-texture sample, the BRH texture improved the ductility and tensile strength simultaneously, due to the operation of non-basal slips within basal-oriented grains and the strong work hardening ability contributed by the basal-random grain boundaries. Besides, the basal-random grain boundaries in BRH texture were beneficial to improve the deformation compatibility by transforming the dominant carrier of local stress from original random-oriented grains to basal-oriented ones. This work aims to provide new insight into improving the mechanical properties of Mg alloys by texture coordinated deformation. [Display omitted] [ABSTRACT FROM AUTHOR]

• The eutectic Mg 2 Si in Al-11Mg 2 Si alloy was modified to spherical particles with 0.2 wt% Ca-Sb addition. • Adding 1.0 wt% Ca-Sb resulted in a microstructure transition from hypoeutectic to hypereutectic characteristics in Al-11Mg 2 Si alloy. • The 0.2 wt% Ca-Sb modified alloy exhibits an improvement in elongation to failure and ultimate tensile strength. • The modification mechanisms and the reasons for the enhanced mechanical properties were discussed in detail. The combined addition of 0.2 wt% Ca-Sb in Al-11Mg 2 Si alloy led to significant refinement of the eutectic Mg 2 Si from a coarse, needle-like morphology to spherical particles. Specifically, a further increase of Ca-Sb addition to 1.0 wt% resulted in the microstructure transition from hypoeutectic to hypereutectic characteristics. The refinement of eutectic Mg 2 Si could be attributed to the selective adsorption of Ca and Sb atoms on Mg 2 Si surfaces, which inhibited the growth of the eutectic phase in the preferential growth direction. Importantly, Ca and Sb elements were involved in the formation of heterogeneous nuclei for primary Mg 2 Si when Ca-Sb content increased to 1.0 wt%, which introduced the transition of composition from hypoeutectic to hypereutectic structures. Comparing to the unmodified alloy, the Al-11Mg 2 Si alloy modified with 0.2 wt% Ca-Sb exhibited significantly enhanced elongation to failure of ~7.9% (from ~1.3% of the unmodified alloy) and ultimate tensile strength of ~222 MPa (from ~180 MPa of unmodified alloy). The spheroidization of eutectic Mg 2 Si after complex modification is believed to be the underlying reason for the greatly enhanced tensile properties. [ABSTRACT FROM AUTHOR]

Achieving high strength-ductility synergy is a great challenge in low-alloyed Mg alloys. In this work, a new Mg–1.0Zn–0.45Ca–0.35Sn–0.2Mn (wt.%, ZXTM1000) alloy was designed and fabricated by sub-rapid solidification (SRS) to overcome the dilemma. After hot rolling and annealing, the new alloy sheet exhibited an excellent tensile yield strength (YS, ∼270 MPa) and elongation (∼21%). Microstructure characterization revealed that the high YS was mainly attributed to the fine grains (∼3 μm) and high density of spherical Ca 2 Mg 6 Zn 3 , Mg 2 Ca, and α-Mn precipitates. Moreover, the homogeneous grain size distribution, weakened TD-split texture and the activation of multiple types of slips contributed to the enhanced ductility. The findings demonstrate an effective way to fabricate low-alloyed Mg alloys with high strength and ductility by combining the SRS and hot rolling. Image 1 • A designed Mg–1.0Zn–0.45Ca–0.35Sn–0.2Mn (wt.%, ZXTM1000) alloy was fabricated by sub-rapid solidification. • The rolled and annealed ZXTM1000 alloy exhibits an good balance of yield strength (∼270 MPa) and elongation (∼21%). • EBSD-assisted slip trace analysis was utilized to determine the type of slips. • The reasons for the high strength-ductility synergy were discussed in detail. [ABSTRACT FROM AUTHOR]

The present study investigated influences of the Al 3 Sc particle content on the evolution of bimodal grain structure and mechanical properties at both room and elevated temperatures of Al–7Mg–Sc alloys processed by hard-plate rolling (HPR). Bimodal grain structures were obtained in HPRed Al–7Mg–Sc alloys where ultrafine/fine grains decreased in size and increased in amount with increasing volume fraction of Al 3 Sc precipitates. The formation and evolution of bimodal grain structure are associated with (i) the different stability of various-orientated grains, and (ii) the volume fraction of Al 3 Sc precipitates. Ultrafine/fine (sub) grains form preferentially along grain boundaries (GBs) of <001>//normal direction (ND)- and <111>//ND-oriented coarse grains during HPR. In contrast, the <101>//ND-oriented coarse grains show relatively high stability nearly without subdivision. Furthermore, increased volume fraction of Al 3 Sc precipitates in Al–7Mg–0.4Sc promotes dislocation accumulation, favoring recrystallization nucleation, and meanwhile restricts grain growth, which results in more and refined ultrafine/fine grains. Thereby, the refined grain structure and increased volume fraction of Al 3 Sc precipitates in the Al–7Mg–0.4Sc alloy contribute to improved room-temperature yield strength (YS) and elongation, i.e. ~482 MPa and ~8%, which is much higher than that of ~420 MPa and ~4% in the binary Al–7Mg alloy. Meanwhile, Al–7Mg–0.4Sc exhibited higher hardness when annealed at 150–300 °C and also higher YS when subjected to a tensile test at ≤ 200 °C due to the more stabilized grain structure pinned by dispersed Al 3 Sc and additional strengthening effect from Al 3 Sc precipitates. Nevertheless, when subjected to a tensile test at ≥ 250 °C, the Al–7Mg–0.4Sc alloy exhibited much lower YS than binary Al–7Mg. The transition could be explained by more favored grain boundary sliding (GBS) and great dislocation loss, due to the easier occurrence of dynamic recrystallization (DRX) in Al–7Mg–0.4Sc during tensile test at elevated temperatures. • Sc addition changed the bimodal grain structure in HPRed Al–7Mg–Sc alloys. • Above transitions are studied based on stability of various-orientated grains and Al 3 Sc. • The Al–7Mg–0.4Sc showed higher yield strength (YS) when tensioned at ≤ 200 °C. • The Al–7Mg–0.4Sc exhibited much lower YS than Al–7Mg when tensioned at ≥ 250 °C. • Lower YS is attributed to easier dynamic recrystallization in tensioned Al–7Mg–0.4Sc. [ABSTRACT FROM AUTHOR]

An intense texture is usually developed in conventional Mg alloys after deformation, resulting in unsatisfactory formability at room temperature. In the present work, a low-alloyed and weak-textured Mg-1.5Zn-0.2Ca (wt.%) alloy that exhibited an advantageous combination of strength and ductility was developed, with an ultimate strength of ∼270 MPa and fracture elongation of ∼30%. The role of Zn addition in the texture and microstructure evolution was systematically investigated. The Mg-xZn-0.2Ca (x = 0.5, 1.0, 1.5, and 2.0 wt%) alloys with increasing Zn content stored additional deformation energy, which accelerated the static recrystallization (SRX) process and resulted in a gradual weakening of the annealing texture. The co-addition of Zn and Ca contributed to the random SRX nucleation and the enhanced solute dragging effects by decreasing grain boundary energy, leading to a weaker texture in the Mg-1.5Zn-0.2Ca alloy than that in the Mg-1.5Zn and Mg-0.2Ca alloys after annealing. The excellent ductility of Mg-1.5Zn-0.2Ca alloy was attributed to the simultaneous increment of uniform elongation and post-uniform elongation as Zn content increases, benefited from its weakened texture and improved failure mode, respectively. This work provides valuable insights into the development of novel low-alloyed Mg sheets with a weak texture, which possess great potential for direct forming to near-net-shaped products without tearing and fracturing. • A weak textured Mg-1.5Zn-0.2Ca alloy with balanced mechanical properties was developed. • Increasing Zn content facilitates SRX, leading to gradual texture weakening of the alloys. • Zn and Ca solutes lead to solute dragging effects and benefit texture weakening. • The weakened texture and improved failure mode benefit ductility of Mg-1.5Zn-0.2Ca alloy. [ABSTRACT FROM AUTHOR]

Owing to the low alloying content in commercial wrought Mg alloys, their strengthening potential is greatly suppressed. It is difficult to achieve the synergy of high strength and formability for Mg alloys. In the present work, a novel high-alloyed Mg–6Al–1Zn–1Sn-0.5Bi (AZTB6110) alloy was designed by multi-component composition design and subjected to a fabrication route coupling sub-rapid solidification and controlled rolling. The alloy has excellent tensile properties, i.e. yield strength (YS) of ~260 MPa, ultimate tensile strength (UTS) of ~363 MPa and elongation of ~15%. The role of Al content (4, 6 and 8 wt %) on microstructure and tensile properties was systematically investigated in the AZTB alloys. When the Al content reaches 6 wt %, the combined pining effects of nano- and submicro-precipitates (Mg 17 Al 12 and Mg 2 Sn) hinder the grain growth and result in the finest grain size (~3 μm) among the studied alloys. The refined grains as well as densely dispersed fine Mg 17 Al 12 and Mg 2 Sn particles result in the best tensile yield strength in AZTB6110 compared to the other alloys. Meanwhile, the high ductility is benefited from the strong work-hardening capacity resulting from the interaction of dislocations with Al, Zn, Sn and Bi solutes and numerous nano-precipitates. Such a designed alloy helps to improve the development of high-alloyed multicomponent Mg alloys with high performance, which broadens the composition range and application of traditional wrought Mg alloy sheets. [ABSTRACT FROM AUTHOR]

Effects of Sb modification on the eutectic microstructure and tensile properties of hypoeutectic Al–11Mg 2 Si alloy were systematically investigated in this work. Eutectic Mg 2 Si phase in hypoeutectic Al–11Mg 2 Si alloy was successfully refined from the long rod-like structure into fine spherical morphology when introducing 0.2 wt% Sb, whereas 1.0 wt% Sb reversely led to the formation of coarse eutectic Mg 2 Si phase. Specifically, the elongation to failure in the 0.2 wt% Sb modified alloy was significantly improved to 9.7% as compared to the unmodified counterpart (1.5%), and the ultimate tensile strength increased from 183 MPa to 208 MPa. This result can be attributed to the spheroidization of eutectic Mg 2 Si phase with Sb modification, which greatly relieved the stress concentration and restrained the crack source from initiating and propagating. The achieved results could shed new light on a more efficient and economical way to obtain high-performance hypoeutectic Al–Mg 2 Si alloys. [ABSTRACT FROM AUTHOR]