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The influences of Al content on microstructure, mechanical properties, stretch formability and thermal conductivity of Mg-1.5Zn-0.3Ca-xAl-0.2Mn (x: 0.2, 0.5, 1, 1.25, 1.5, 2, wt%) alloys were investigated. With increasing the Al content from 0.2 wt% to 2 wt%, the texture changed from the TD-split texture to the quadrupolar texture at the Al content of 1.25 wt%, and finally became the RD-split texture with an increased texture intensity. The change of texture can be attributed to the formation of Al 2 Ca phase, which weakens the segregation of Ca at grain boundaries due to the decreased amount of Ca solute atoms in the α-Mg matrix. In addition, Al-Mn precipitates changed from a spherical shape to a rod shape accompanied by a largely increased Al/Mn ratio and a decreased amount of precipitates, when the Al content was increased to be larger than 1 wt%. The 0.2–1.5 wt% Al added alloys exhibited excellent stretch formability with the Erichsen values of 8.4–9.1 mm, which were much larger than that (6.8 mm) of the 2 wt% Al added alloy due to texture effect. The 1 wt% Al added alloy had the largest Erichsen value of 9.1 mm, while the 0.2 wt% and 2 wt% Al added alloys exhibited much higher yield strength (165 and 171 vs. 144 MPa). The thermal conductivity continuously decreased with increasing the Al content. Compared to the 2 wt% Al added alloy, the 0.2 wt% Al added alloy exhibited a much higher thermal conductivity (140 vs. 105 W/(m·K)) benefiting from the low concentration of Al solute atoms in the α-Mg matrix. Consequently, a combination of strong mechanical strength, excellent stretch formability and high thermal conductivity was achieved in the low Al-containing alloys with 0.2–0.5 wt% Al. • Mg-1.5Zn-0.3Ca-(0.2–2)Al-0.2Mn alloys with different Al contents were prepared. • High Al content caused texture change from TD-split to RD-split via quadrupole. • 1 wt% Al alloy with TD-split texture has the best formability but low strength. • Thermal conductivity continuously decreased with increasing Al content. • Excellent properties were simultaneously achieved in the low Al-containing alloys. [ABSTRACT FROM AUTHOR]

Static recrystallization behavior of Mg-1.5Zn-0.2Ce (wt%) alloy rolled at 480 °C was investigated at different annealing stages using quasi-in-situ electron backscattered diffraction (EBSD) analyses, which were carried out repeatedly in the same region to trace microstructural evolution. In the as-rolled condition, double twins exhibit the highest fraction compared with tensile and compression twins. Double twins mostly exist in deformed grains with basal orientations, and statically recrystallized grains mainly nucleate at the intersections of double twins and pre-existing grain boundaries. Statically recrystallized grains tend to exhibit TD-tilted orientations and grow along double twins to consume adjacent basal-oriented grains. This is the main reason for inducing the change from a RD-split texture to a well-weakened TD-split texture during annealing. The residual unrecrystallized grains with TD-tilted orientations and the growth advantage of TD-tilted grains also enhance the formation of TD-split texture. [ABSTRACT FROM AUTHOR]

The microstructure and mechanical properties of flame-resistant AZX912 magnesium alloy extruded at different temperatures in the range of 250–400 °C were investigated. With decreasing extrusion temperature from 400 °C to 250 °C, the grain size of dynamically recrystallized grains significantly decreased from 13.6 to 1.8 µm, and the amount of fine Mg 17 Al 12 precipitates, with sizes of 50–200 nm, increased due to dynamic precipitation. The extrusion texture, with the basal plane and < 10 1 ¯ 0 > direction, mostly parallel to the extrusion direction, was remarkably strengthened as the extrusion temperature increased. This may be attributed to the enhanced activity of the prismatic slip. Nanoscale Mg 17 Al 12 precipitates significantly enhanced the mechanical strength, but deteriorated the ductility. The bar extruded at 250 °C exhibited the highest mechanical strength, which was due to the combined effect of the remarkably refined grain structure and the large amount of nanoscale Mg 17 Al 12 precipitates. The extrusion at 400 °C resulted in the lowest tensile elongation, which was attributed to both grain coarsening and basal texture strengthening. The bar extruded at 300 °C exhibited a good balance between mechanical strength and tensile ductility. [ABSTRACT FROM AUTHOR]

The discharge behaviors of rolled Mg–6 mass%Al–0.3 mass%Mn–2 mass%Ca (AMX602) and Mg–6 mass%Al–0.3 mass%Mn (AM60) alloys used as anodes for Magnesium–air batteries were investigated. The AMX602 alloy exhibited superior discharge properties compared to the AM60 alloy, especially at low current density. The discharge products of the AMX602 alloy were dense and thin, and many cracks were observed at all current densities. In addition, the discharge products were detached at some sites. These sites often corresponded to the positions of Al 2 Ca particles. The comparison of the discharge and corrosion tests indicated that the dense and thin discharge products of AMX602 were easily cracked by dissolution of the Mg matrix around Al 2 Ca particles, and the cracks promoted the penetration of the electrolyte into the discharge products, retaining the discharge activity. In contrast, concerning the AM60 alloy, thick discharge products were formed on the surface during discharge, and cracking of the discharge products hardly occurred, degrading the discharge properties. Localized and deeply corroded pits that could result from the detachment of metal pieces from the anode during discharge were partly observed in the AM60 alloy. It is suggested that these detached metal pieces are another reason for the low discharge properties of the AM60 alloy. [ABSTRACT FROM AUTHOR]

The effects of aging precipitation on microstructure, deep drawing formability and tensile properties, were investigated for Mg-6Al-1Zn (AZ61) alloy sheets. The alloy aged at 175 °C for 96 h with high strength exhibited a significant improvement in deep drawability with an increased limiting drawing ratio (LDR) from 1.5 to 1.9, when slightly increasing deformation temperature from room temperature to 100 °C. This LDR (1.9) was even larger than that (1.75) of the unaged alloy drawn at 100 °C. The improved deep drawability can be attributed to the prevention of cracking at the edge of drawn cup, which is closely related to the restrictions of growth of tensile twins and basal slip due to Mg 17 Al 12 precipitates, resulting in the delayed texture strengthening during deformation. The proposed idea of utilizing aging precipitation provides a new strategy for the development of Mg alloy sheets with superior deep drawing formability and high strength. [Display omitted] [ABSTRACT FROM AUTHOR]

AZ61 and AM60 magnesium alloys, with higher mechanical strengths than that of the most commonly used AZ31 alloy, were subjected to high-temperature rolling. Although the basal textures of the as-rolled sheets of both alloys were significantly weakened by annealing, the texture weakening was more significant in the latter than in the former. In addition, splitting of the basal pole was not retained after annealing for the AZ61 alloy, but this type of texture was preserved in the case of the AM60 alloy. The formation of statically recrystallized grains with dispersed orientations resulted in the aforementioned change in texture. The difference in the static recrystallization behavior could be attributed to the solute effect of zinc atoms. The annealed AZ61 and AM60 alloy sheets exhibited excellent stretch formability at room temperature, with Erichsen values of 7.8 and 8.5 mm, respectively, comparable to those of aluminum alloys. The higher Erichsen value for the AM60 alloy compared to that of the AZ61 alloy resulted from the more weakened basal texture and the splitting of the basal pole with an inclination angle of ±20° in the rolling direction, which are favorable for basal slip during sheet forming. [ABSTRACT FROM AUTHOR]

Abstract: Mg–3Al–1Zn magnesium alloy sheets rolled at 350°C, 450°C and 525°C, which exhibit approximately the same grain size but a significant decrease in basal texture intensity with increasing rolling temperature, were used for investigating the influence of initial texture on deep drawing behaviour at room temperature. The sheets rolled at 350°C and 450°C fracture at drawing ratios of 1.5 and 1.7, respectively, while the sheet rolled at 525°C can be successfully drawn at a large drawing ratio of 1.8. The fracture site changes from the shoulder of drawn cup to the edge of the flange with the weakening of initial basal texture. At the flange, the basal texture dramatically changes to the TD-texture with basal planes perpendicular to the sheet plane accompanied with sheet thickening. Both tensile twinning and basal slip contribute to this texture change due to compressive stress along the circumferential direction. In the case of weak initial texture, relatively restricted tensile twinning and more activated basal slip delay the development of the TD-texture, which is favoured for maintaining deformation capability at the flange and in turn enhances deep drawability. The deformation behaviour is discussed in terms of the change in Schmid factor for basal slip during deep drawing. [Copyright &y& Elsevier]

Abstract: The annealing behaviours of Mg–3Al–1Zn magnesium alloy sheets warm rolled at 225°C and 150°C using differential speed rolling, which are mainly characterized by dynamic recrystallized microstructure and deformation microstructure, respectively, were investigated at different annealing stages. Static recrystallization occurs for the sheet rolled at 150°C while only grain growth proceeds for the sheet rolled at 225°C. For the sheet rolled at 225°C, the grain growth of dynamic recrystallized grains eliminates the basal pole inclination in the rolling direction. In contrast, for the sheet rolled at 150°C, the grain growth after static recrystallization retains the basal pole inclination, which is favoured for sheet forming. This difference in texture evolution may be attributed to the dynamic or static recrystallization prior to grain growth, which results in residual dislocation densities for the former and thus leads to the preferential growth of harder oriented basal grains at the centre of (0001) pole figure with lower dislocation densities during annealing. [Copyright &y& Elsevier]

Abstract: The Mg–3Al–1Zn magnesium alloy sheets rolled at 573 and 798K characterized by strong and weak basal textures, respectively, were further subjected by a single high temperature rolling pass at 798K. The sheet rolled only at 798K throughout rolling exhibits a double peak texture in both of as-rolled and annealed conditions. By contrast, for the sheet rolled at 573 and 798K, the reduction rate of basal texture intensity is larger and the single peak of the rolling texture changes to the double peak with basal poles largely tilting in the RD at ∼20° after annealing, which is rarely observed in wrought magnesium alloys. This phenomenon is resulted from static recrystallization and may be related to enhanced pyramidal 〈c+a〉 slip during high temperature rolling due to the initial strong basal texture. [Copyright &y& Elsevier]

Abstract: The microstructural and textural evolution during post-annealing as well as mechanical properties of a Mg–4Y–3RE magnesium alloy sheet processed by differential speed rolling at 823K were investigated. The as-rolled sheet exhibits deformation microstructure regardless of the high rolling temperature. Static recrystallization occurs around second-phase particles as a result of particle-stimulated nucleation and also at pre-existing grain boundaries due to solute effects of rare-earth elements, resulting in randomization of basal texture. Despite a large amount of second-phase particles, the weakened texture leads to a moderate stretch formability with an Erichsen value of 4.4. [Copyright &y& Elsevier]

Abstract: The effects of increasing rolling temperature from 723K to 828K at the last rolling pass on microstructure, texture, mechanical properties and stretch formability of a Mg–3Al–1Zn magnesium alloy previously rolled at 723K were investigated. In the as-rolled condition, the basal texture strengthens slightly with increasing the rolling temperature whereas it weakens more remarkably after static recrystallization during annealing for the sheets rolled at higher temperatures. Only by increasing the rolling temperature from 723K to 798K, the Erichsen value is significantly increased from 4.5 to 8.6 due to the weakened texture for the annealed sheets. Further increasing the last rolling temperature does not appear to further improve the stretch formability. [Copyright &y& Elsevier]

Abstract: The recrystallization and grain growth behaviour of Mg–3Al–1Zn alloy sheets with a deformation microstructure, obtained by a combination of high-temperature rolling and subsequent warm rolling, was investigated at different stages of annealing. The basal texture was significantly weakened as a result of the formation of new grains with a largely altered c-axis orientation relative to the initial basal orientation owing to discontinuous static recrystallization during primary recrystallization. The new grains nucleated mostly at the pre-existing grain boundaries rather than at the intersections of twins or within the twins. Subsequent grain growth led to further progression of the texture weakening accompanied by an enhancement in the basal pole inclination. [Copyright &y& Elsevier]

The Mg–3Al–1Zn magnesium alloy sheets with initial extrusion and casting microstructures were symmetrically rolled at a high temperature of 823K, followed by a warm rolling at 498K. The initial texture plays a vital role in texture development and results in inclination angle of split basal pole varying from ±15° to ±40°. The sheet rolled perpendicular to extrusion direction exhibits a homogeneous microstructure with an inclination angle of ±25° and the highest Erichsen value of 9.7. [Copyright &y& Elsevier]

Mg–3Al–1Zn alloy sheets were rolled at high temperatures up to 823K and subsequently rolled at 498K using differential speed rolling. The basal texture intensity dramatically weakens with a largely tilted basal pole after annealing. The Erichsen value significantly increases from 3.7 to 9.5 with an increase in the rolling temperature from 498 to 823K prior to warm rolling due to texture effects. This high Erichsen value is comparable to those of aluminum alloys. [Copyright &y& Elsevier]

Abstract: The microstructural and textural evolution of the hot-extruded AZ31 alloy plate during differential speed rolling (DSR) has been investigated. For the hot-extruded plate, a large texture gradient exists in the thickness direction while the grain size distribution is nearly homogenous. The textural evolutions at near-surface and mid-layer regions are different between the DSR processed and the normal symmetric rolled sheets. The inclination of basal pole at the mid-layer increases at an accelerating rate with progress of the DSR processing due to the enhancement of the unidirectional shear bands. The deformation tends to concentrate on the previously formed shear bands, which exhibit a favored crystalline orientation for further shear localization. [Copyright &y& Elsevier]

The influence of reduction per pass over the range of 9–63% on the microstructure and texture of Mg–3Al–1Zn magnesium alloy sheets processed by differential speed rolling at the same total reduction of 63% have been investigated. With increasing reduction per pass, the number of unidirectional shear bands increases, resulting in a more homogeneous microstructure and a weaker basal texture at mid-layer. The inclination direction of the basal pole with respect to the rolling direction depends on the reduction per pass. [Copyright &y& Elsevier]

Abstract: A heat-treatable AZ80 magnesium alloy has been subjected to differential speed rolling (DSR) at a large thickness reduction per pass of 33%, and microstructure, texture, mechanical properties, stretch formability as well as texture evolution during stretch forming have been investigated. The basal pole of the DSR-processed sheet tilts toward the rolling direction at 15°. The as-rolled sheet exhibits a combination of high strength (tensile strength: 329MPa) and high ductility (fracture elongation: 25%). The Erichsen value at room temperature improves from 3.7 to 4.5 compared with the normal-rolled sheet. The enhancement of the stretch formability can be attributed to the texture effects due to the same grain size of 7μm. The DSR-processed sheet exhibits a larger Schmid factor for basal slip and the inclination of basal pole retains during the stretch forming. The aging treatment remarkably enhances the mechanical strength further while it significantly deteriorates the formability. [Copyright &y& Elsevier]

• Mg-3Zn-0.5Ca-0.5Al-xMn alloys with different Mn contents were investigated. • Mechanical strength significantly improved with increasing Mn content. • High strength and high formability were simultaneously achieved in 1 wt% Mn alloy. • 1 wt% Mn alloy also has high thermal conductivity regardless of high Mn content. • Excellent properties are related to dense Al-Mn nanoscale spherical precipitates. [Display omitted] Tensile properties, formability and thermal conductivity of Mg-3Zn-0.5Ca-0.5Al-xMn (x: 0.1–1.5 in wt%) sheet alloys with different Mn contents were investigated. Benefitting from dense Al-Mn nanoscale spherical precipitates, yield strength was significantly enhanced by 39 MPa with increasing the Mn content from 0.1 wt% to 1 wt%. In the meanwhile, excellent formability was maintained with Erichsen values larger than 8 mm. Further increasing the Mn content to 1.5 wt% did not contribute to strengthening due to the formation of coarse β-Mn particles. In spite of larger additive amount, thermal conductivity improved for the 1 wt% Mn added alloy compared to the 0.1 wt% Mn added alloy due to the increased amount of Al-Mn nanoscale spherical precipitates, which reduced a content of Al solute atoms. High strength (average yield strength: 180 MPa), high formability (Erichsen value: 8.5 mm) and high thermal conductivity (133 W/(m K)) were simultaneously achieved in the 1 wt% Mn added alloy. [ABSTRACT FROM AUTHOR]

Abstract: The microstructure and the texture of the Mg–3.10Al–1.06Zn–0.35Mn (in wt.%) alloy processed by differential speed rolling (DSR) were investigated by optical microscopy, X-ray texture analysis and electron backscattered diffraction (EBSD) analysis. The DSR processed sheet exhibited the unidirectional shear bands with an inclination to the rolling direction. The macro-texture analysis results showed a large inclination of c-axis toward the opposite direction of the rolling direction at about 15°. On the other hand, the micro-texture analysis revealed that the inclination directions of c-axis were reverse between the shear bands and the remaining coarse grain regions, and the latter dominated the macro-texture. This anomalous texture can be attributed to the formation of the unidirectional shear bands. [Copyright &y& Elsevier]

Precipitation hardening provides one of the most common strengthening mechanisms for magnesium (Mg) alloys. Here, we report a new precipitation-hardenable Mg sheet alloy based on the magnesium–silver–calcium system. In a solution treated condition (T4), the strength of Mg–xAg–0.1Ca alloys is enhanced with increasing the Ag content from 1.5 wt.% to 12 wt.%. The Mg–12Ag–0.1Ca (wt.%) alloy sheet shows moderate tensile yield strengths of 193 MPa, 130 MPa, 117 MPa along the rolling direction (RD), 45° and transverse direction (TD) in the T4-treated condition. Subsequent artificial aging at 170 °C for 336 h (T6) increases the tensile yield strengths to 236 MPa, 163 MPa and 143 MPa along the RD, 45° and TD, respectively. This improvement in the tensile yield strength by the T6 treatment can be ascribed to the formation of AgMg4 precipitates lying on the {11 2 ¯ 0}ɑ and pyramidal planes. Our finding is expected to stimulate the development of precipitation-hardenable Mg–Ag-based wrought alloys with high strength. [ABSTRACT FROM AUTHOR]

This work investigated effects of silver (Ag) content on the microstructure, texture and mechanical properties of magnesium–silver–calcium alloys by a combined experimental and numerical approach. A series of ternary magnesium–silver–calcium alloys with Ag concentrations between 0.3 and 12 wt% were prepared by hot-extrusion, hot-rolling followed by annealing. As-rolled sheets showed rolling direction split textures with double peaks irrespective of the Ag content. A new component where (0002) basal poles tilted from the normal direction toward the transverse direction (TD) appeared when the Ag content was increased to 1 wt% after annealing. The Mg–xAg–0.1Ca (x = 0.3, 1, 2 and 3) alloys showed excellent room temperature (RT) formability, which could be mainly ascribed to weak basal textures developed after annealing. When the Ag content was increased to 6 wt%, a weak TD-split texture with a homogeneous fine-grained microstructure was developed, which resulted in excellent RT formability and high strength. In contrast, the Mg–12Ag–0.1Ca alloy showed much lower RT formability and ductility in comparison with Mg–Ag–Ca alloys with lower Ag concentrations due to the presence of coarse AgMg 4 particles. Visco-plastic self-consistent simulation results revealed that the activity of prismatic slip was increased with increasing the Ag content and the enhanced activity of prismatic during rolling may partially lead to the formation of TD-split texture in the formable Mg–Ag–Ca alloys during annealing. • Mg–xAg–0.1Ca (x = 0.3, 1, 2, 3, 6 and 12 wt%) alloys showed weak basal textures. • Mg–0.1Ca alloys with Ag no more than 3 wt% showed excellent formability. • A Mg–6Ag–0.1Ca (wt.%) alloy exhibited a high strength and excellent formability. • Activity of prismatic slip increased with increasing Ag content. [ABSTRACT FROM AUTHOR]

In this study, the microstructures, mechanical properties, and ignition temperatures of hot-rolled Mg-1.5Zn-X (X: Ca and/or Sr) alloys were investigated. The Mg-1.5Zn, Mg-1.5Zn–1Ca and Mg-1.5Zn–1Sr alloys had the mean grain sizes of 56.1 μm, 8.7 μm, and 18.5 μm, respectively. This indicates that Ca addition exerts a stronger effect on grain refinement than Sr addition. Both Ca and Sr additions significantly weakened the basal texture to approximately one-quarter in intensity for the annealed sheets. Ca-containing alloys exhibited texture splitting in the transverse direction, while Sr-containing alloys tended to maintain it in the rolling direction after annealing. The Ca and Sr additions improved the mechanical strength considerably due to grain refinement, which overcompensated for the influence of texture softening. Meanwhile, benefiting from the weakened textures, the 1% Ca and Sr additions remarkably increased the Erichsen values from 3.8 to 8.0 and 7.1, respectively. However, further addition resulted in the deterioration of both tensile ductility and stretch formability due to the cracking of secondary-phase particles. Ca addition had a better effect on enhancing the flame-retardant property than Sr addition, and 2% Ca and Sr additions increased the ignition temperature from 629 °C to 800 °C and 720 °C, respectively. [ABSTRACT FROM AUTHOR]

Small amounts of transition elements: Ti, Mn, Fe, Co, and Ni, have been added to a Mg–0.1Ca (wt%) alloy to elucidate their additions on the microstructure and room temperature (RT) mechanical properties. Only Ni was effective in weakening the texture intensity and thus led to the improvement in RT formability and ductility, whereas the other elements were basically no effect. The microstructural characterization by high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) in conjunction with energy-dispersive X-ray spectrometry (EDS) and numerical simulation using a grain boundary (GB) phase model indicates that the Ca and Ni co-segregated to the GB of the Ni-containing alloy, while the GB of the other alloys was enriched with Ca only. Further investigations by a correlative electron backscatter diffraction and STEM-EDS reveal that the transverse direction (TD) oriented GBs had significantly lower concentration of Ca and Ni compared to the basal-oriented GBs, which resulted in the development of the TD-split texture in the Ni-containing alloy. A compositionally optimized Mg–0.1Ca–0.1Ni (wt%) alloy showed a large index Erichsen value of 8.5 mm in the sheet form, and exhibited a high tensile yield strength of 238 MPa with a moderate fracture elongation of 14% in the form of an extruded rod. Due to the addition of small amounts of alloying elements, the newly developed Mg–0.1Ca–0.1Ni alloy had an excellent thermal conductivity of 154 W/(m·K) which is even higher than that of a commercial 5052 Al alloy. [Display omitted] [ABSTRACT FROM AUTHOR]

Abstract: Though Mg alloys are promising candidates for biodegradable stents, it is very difficult to fabricate stent tubes with high dimensional accuracy using Mg alloys because of their low deformability. This study aimed to develop thin-walled, high-quality Mg alloy tubes with good performance in stent applications. Cold drawing with a fixed mandrel was carried out for extruded Mg-0.8%Ca and AZ61 alloy tubes using optimized drawing parameters and lubrication, and stent tubes with 1.5–1.8mm outer diameter and 150μm thickness were fabricated. A dimensional evaluation showed that the tube dimensional errors were within 0.02–2.5%. Also, an immersion test of pure Mg with different crystal orientations showed that the crystal orientation affected the corrosion properties, results that are the same with other Mg alloys. The crystal orientation of the stent tube could be controlled by changing the deformation amount and direction in the drawing, showing that it is possible to further improve the biodegradability of stents by approaching their fabrication from a processing aspect. [Copyright &y& Elsevier]