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An in-plane precompression and annealing process (PCA) was carried out on a Mg–3Al–1Zn thin sheet to introduce a completely tilted texture. Unlike the conventional c-axis∥normal direction (ND) basal texture which usually hinders the deformation ability of the Mg sheet during secondary forming, such a special texture component could supply soft orientations of extension twinning for subsequent rolling. The results indicated that the new grain orientations induced by extension twinning, which are dependent on consuming the pre-introduced tilted texture during rolling, would lie around the ND. This positioning could offer diverse orientation gradients along different directions. Meanwhile, such randomly distributed orientation gradients could provide relatively random growth directions for the new recrystallized grains during annealing and contribute to weakening of the basal texture, as well as promoting the symmetry of texture distribution (distribution of basal poles show rotational symmetry around the (0002) pole figure center). As expected, the "precompressed + annealed" and subsequently "rolled + annealed" sample showed improved uniaxial tensile properties (including lower yield strength, higher ductility and more symmetrical planar mechanical performance along different directions) and a considerably improved multiaxial stamping property (Erichsen value increased ~120%) compared with that of the as-extruded sheet or the directly rolled and annealed sample. This study confirmed that preparing soft orientations of extension twinning for subsequent rolling (e.g., employing in-plane precompression along with rolling processes) could be a highly efficient way to optimize the texture and mechanical properties of Mg sheets. [ABSTRACT FROM AUTHOR]

The influence of different rolling paths on the texture and property evolutions of extruded Mg-3Li-3Al-Zn alloy sheet possessed of an asymmetric texture was investigated, aiming to explore appropriate process to minimize the planar anisotropy of the sheet. The results indicated that the sheet exhibited quite different texture and property evolutions during undergoing different rolling paths, which was mainly due to the extremely deflected basal poles (nearly titled towards to TD). When the rolling process was conducted along its extrusion direction, the pyramidal 〈c+a〉 slip was easily activated, which would lead to strong re-orientation of the a-axis but limited rotation of the c-axis. As a result, the extremely asymmetric texture feature was retained during the subsequent recrystallization annealing and this type of texture modification showed weak effect on improving the planar anisotropy of the sheet. However, when the sheet was rolled along its transverse direction, the {10 1 ¯ 2} extension twin would became the dominated deformation mechanism, which led to sufficient re-orientation of the c-axis by almost 90°. Finally, a symmetric weak texture was introduced during subsequent annealing. This modified symmetric texture distribution along with the efficient microstructure refinement would give rise to accordant deformation behaviors during loading along different directions and thus could minimize the planar anisotropy of the sheet significantly, as well as improve the comprehensive mechanical properties. [ABSTRACT FROM AUTHOR]

Mg-3Al-1Zn round ingots were divided into several pieces and then cobbled together to introduce specific interfaces before direct extrusion. The microstructure, texture and mechanical response of the magnesium alloys processed by conventional extrusion and co-extrusion with introducing various interfaces were examined. The results indicated that the prewired various interfaces played important role on the microstructure evolution and texture modification of magnesium alloys during extrusion, and consequently influenced the tension-compression performance of the extruded alloys. Co-extrusion process by introducing appropriate interfaces during extrusion was suggested as a sample and effective method to enhance the comprehensive mechanical properties of Mg-Al-Zn alloys. [ABSTRACT FROM AUTHOR]

Pre-straining and annealing processes were carried out to enhance the mechanical properties and corrosion resistance of AZ31 sheet by modifying the microstructure and texture. The results showed that by a small tensile deformation along the weak basal textured orientation, the pre-strained AZ31 samples showed higher strength and improved anisotropy after annealing. Furthermore, because the texture reinforcement effect obtained by the pre-deformation was retained during annealing, the corrosion resistance of pre-strained and annealed specimens was enhanced compared with the as-extruded sheet, which was characterised by the evolved hydrogen and the immersed surfaces. This study suggested that appropriate pre-straining accompanied annealing was a potential technique to improve the comprehensive properties of the magnesium alloy sheets. [ABSTRACT FROM AUTHOR]

The mechanical responses of AZ31 Mg alloy sheet processed by pre-hardened at different directions tilting 45° and 90° to the extrusion direction (ED) were compared and evaluated in correlation with the concurrent microstructure and texture evolution. The amount of deformation twinning was sensitive to crystal orientation with respect to the direction of pre-hardening. The tensile twinning could promote the nucleation rate in the following static recrystallization. In addition, the reorientation of the c -axis caused by the {1 0 −1 2} twins had a great influence on work hardening. Twinning could effectively coordinate the deformation texture, and the basal texture intensity was reduced to half after pre-hardening 7% along the transverse direction (TD) after annealing. [ABSTRACT FROM AUTHOR]

Au–20Sn preforms such as microscale thin foils or wires can be widely used as lead-free solder in the high-power optoelectronics and hermetic sealing applications. However, as-cast Au–20Sn eutectic alloy with Au 5 Sn and AuSn phases is intrinsically brittle at room temperature due to limited slip systems associated with their complicated trigonal structure and hexagonal packed structure. In this study, we successfully made an Au–20Sn foil with thickness of 48 μm by multi-pass hot rolling on as-cast alloy with an initial thickness of 4 mm. The microstructure, texture and recrystallization evolutions of the Au–20Sn eutectic alloy during hot rolling process were investigated in detail. The results indicated that plastic instability occurs in the eutectic lamellar structure when the nanoscale layers were subjected to the rolling strain, and promoted the microstructural spheroidization. Besides, the spheroidizing behavior in AuSn phase was found more preferential compared with that in the Au 5 Sn phase. After dynamic recrystallization, <0001>∥TD deformation texture was introduced in the AuSn phase while <0001>∥ND deformation texture was formed in the Au 5 Sn phase. These phenomena were attributed to the difference in slip systems activated in the two phases associated with their different c/a ratios. A transition of dynamic recrystallization mechanism from the initial lamellar phase to the later equiaxed phase (in other words, from continuous dynamic recrystallization mechanism to discontinuous dynamic recrystallization) was observed, as evidenced by the evolutions of in-grain misorientation accumulation and grain boundary migration. Additionally, an interesting recrystallization phenomenon occurred that the AuSn grains could nucleate in the Au 5 Sn phase during hot rolling, which was considered as a strain induced phase decomposition behavior. The present studies can provide insight into understanding microstructural evolution of Au–20Sn eutectic alloy during hot rolling, which enables a further optimization of processing parameters to fabricate Au–20Sn alloy foils with desired microstructure and properties. • Au–20Sn foil with thickness of 48 μm is successfully made by hot rolling process. • Plastic instability occurs in the eutectic lamellar structure during hot rolling. • Different textures are introduced in the AuSn and Au 5 Sn eutectic phases. • Transition of recrystallization from CDRX to DDRX is found in the eutectic alloy. • AuSn phase can precipitate in Au 5 Sn grains which subjected to severe local strain. [ABSTRACT FROM AUTHOR]

Au-20Sn eutectic alloys are an important lead-free solder applied in the welding temperature range from 280 to 350 °C. However, the poor formability originating from the brittle eutectic structure (AuSn + Au 5 Sn) restricts its applications because it is difficult to deform this alloy to the specifications required for industrial applications. In this study, the hot rolling process was carried out on an as-cast Au-20Sn alloy, and the deformation behaviour as well as the spheroidization evolution of the nanolayered structure was investigated in detail because the goal was to evaluate and optimize the thermoforming process of the Au-20Sn alloy. The results indicated that plastic instability occurred across the multilayers during hot rolling, which showed a gradual transition from geometric bending to the "S" type shear mode as the rolling strain increased. As a result, nanostructure spheroidization in a lamellar colony could take place preferentially based on these shear instability regions owing to a high strain accumulation in these places. Even so, the formation of high-angle grain boundaries in the AuSn lamellae occurred faster than that in the Au 5 Sn lamellae, resulting in a higher spheroidizing velocity in the AuSn phase. After spheroidization, a (0001)//transverse direction deformation texture formed in the AuSn phase, while a (0001)//normal direction deformation texture was introduced in the Au 5 Sn phase. Such differences in texture formation were primarily due to the different deformation mechanisms activated in these two phases due to their very different c/a ratios. This study can provide insights to improve the formability of Au-20Sn alloys during thermoforming. Unlabelled Image • Deformation behaviour and spheroidization of the nanolayered Au-20Sn alloy during hot rolling was investigated. • Plastic instability gradually transformed from geometric bending to shear instability across the multilayers was observed. • Nanoscale spheroidization takes place preferentially based on the shear instability regions owing to high strain accumulation. • Different textures were introduced in the AuSn and Au 5 Sn phases due to the activation of different deformation mechanisms. [ABSTRACT FROM AUTHOR]

Effects of Al addition to a Mg–Sn–Ca ternary alloy on its microstructure and tensile properties after extrusion were studied via extrusion of Mg-1.0Sn-0.5Ca- x Al (x ​= ​0, 0.8, 2.4 ​wt%) sheets and analysis of the extruded materials. The results showed that Al addition not only refined the grain size (from 9.8 ​± ​0.7 ​μm to 8.3 ​± ​0.4 ​μm and 7.6 ​± ​0.5 ​μm) but also accelerated the generation of more second phase (from 0.98 to 1.72 and 4.32%). Except for the CaMgSn and Mg 2 Ca in Mg-1.0Sn-0.5Ca alloy, new phase (Mg, Al) 2 Ca appeared after Al addition. The addition of Al into Mg–Sn–Ca alloy induced the textural variation from an initially ED-split double-peaked texture to a weakened texture, i.e., divergent elliptical texture, due to the effect of particle stimulated nucleation. This eventually contributed to the improvement of mechanical anisotropy as well as the higher Hc value and n -value. For the strain hardening behavior when tension along the TD, the prolonged stage Ⅱ of Al-modified alloys was closely connected with the additional TD textural components, accelerating the activation of more basal slip. The decreased θ Ⅲ0 in stage Ⅲ of Al-modified alloys is beneficial to the grain refinement and the emergence of more second phase. [Display omitted] • In conjunction with the SEM photographs, EDS analysis results and simulated solidification path (under the Scheil-Gulliver conditions via using the data from ThermoCalc2016a) reflects that Al addition accelerates the generation of more second phase. • Compared to the only ED-split double-peaked texture of Mg-1.0Sn-0.5Ca alloy, additional TD textural component was generated after Al addition, which predominately due to the PSN effect induced by the formation of more second phase particles (their size >1 ​μm). • Al addition can greatly reduce the mechanical anisotropy of as-extruded Mg–Sn–Ca alloy and accompanied by the higher Hc value and n -value. [ABSTRACT FROM AUTHOR]

Mg-3Al-1Zn (AZ31) alloy sheets fabricated using extrusion dies with angles of 30°, 45°, 60° and 90° were investigated. Finite element method was used to analyze the effective strain distribution in AZ31 Mg alloy during extrusion. The microstructure, texture and final mechanical properties were determined and compared among various extruded AZ31 sheets. Results demonstrated that the difference of effective strain was introduced during extrusion due to the variation in die angles. In the case of the 45° extrusion die, a large difference in effective strain along normal direction could form during sheet forming, which resulted in a uniform microstructure and weak basal texture of extruded AZ31 sheet. Therefore, the sheet processed using 45° extrusion die showed lower yield strength and r -value, but higher ductility and n -value. This study suggested that optimization of extrusion die angle could be an effective method to improve the mechanical properties of AZ31 Mg alloy sheets. [ABSTRACT FROM AUTHOR]

A novel extrusion process, namely, slope extrusion (SE), was proposed to produce Mg–3Al–1Zn alloy sheet, thereby tailoring the strong basal texture of conventional extruded (CE) sheet. The grain morphology and texture were examined, and the tensile tests were performed along 0°, 45°, and 90° with extrusion direction. Moreover, the finite element simulation was performed to have a better understanding on the extrusion processes. An elongated weak double-peak texture titled from extrusion direction to transverse direction about 48° was obtained for the SE sheet and meanwhile the two peaks titled away from normal direction by ~ 35°. Therefore, the SE sheet showed lower yield strength and higher ductility compared with CE sheet. Especially, in terms of the transverse direction specimen of the SE sheet, the ductility reached 27.3%, which was considered as an excellent value for the wrought AZ31 sheet. [ABSTRACT FROM AUTHOR]

Effects of Al addition (0.0, 0.5, 3.0, 7.2 wt%) on microstructure, texture and mechanical properties of Mg-3.5Ca based alloys were investigated. Our results revealed that the addition of Al to the as-cast Mg-3.5Ca alloy resulted in the transformation of precipitated secondary phase from Mg 2 Ca to (Mg, Al) 2 Ca, Al 2 Ca and even Mg 17 Al 12 phase. Moreover, the as-cast microstructure evolution influenced dynamic recrystallization and texture formation in the subsequent extrusion process. As Al content increased from 0.0 to 7.2 wt%, the elongation to fracture (EL) of as-extruded Mg-3.5Ca alloy was monotonously increased from 1.9% to 9.8% in tension, while counterparts were changeless in compression. As-extruded Mg-3.5Ca-3.0Al alloy showed higher yield and ultimate strength increased by about 42.2 MPa and 71.4 MPa than those of extruded Mg-3.5Ca alloy in tension, respectively. Moreover, when Al addition was up to 7.2 wt%, both tensile yield strength and ultimate tensile strength were in steep decline. The effects of Al addition on compressive mechanical properties (compressive yield strength and ultimate compressive strength) were similar to that in tension. Especially, significantly deteriorated tension-compression asymmetry (TCA) of Mg-3.5Ca-7.2Al alloy was ascribed to grain coarsening and secondary phase transformation. Besides, Al addition also had a significant impact on the hardening capacity (Hc) and strain hardening behavior of Mg-3.5Ca alloy. In particular, as 7.2 wt% Al was added, the hardening capacity of the Mg-3.5Ca alloy was significantly increased from 0.09 to 0.56 in tension. As a result, proper Al addition to Mg-3.5Ca alloy could improve the comprehensive mechanical performance, whereas excessive Al addition not only significantly decreased the strength, but also deteriorated the TCA performance. [ABSTRACT FROM AUTHOR]

In the present study, Mg–3Al–1Zn (AZ31) alloy sheets were fabricated by conventional extrusion (CE) and asymmetric extrusion (AE) processes. The microstructures, textures and mechanical properties of the AE and CE AZ31 sheets were examined and compared. The results showed that a tilted weak basal texture and microstructure refinement were obtained in the AE AZ31 sheet compared with the CE AZ31 sheet. The reason for the texture weakening and microstructure refinement was ascribed to an introduction of large effective strain gradient throughout the normal direction during the AE process. In addition, the AE AZ31 sheet exhibited lower yield strength and r -value, but larger ductility and n -value. Improving mechanical properties for extruded AZ31 sheet were achieved by the AE process. [ABSTRACT FROM AUTHOR]

Cold rolling of the as-extruded Mg–3Al–1Zn (AZ31) sheets containing different Li contents (Li=1, 3, 5; wt%) was performed at room temperature with a rolling reduction of 5%, and the microstructure, texture and tensile properties of the cold rolled and annealed sheets were investigated. The results indicated that the AZ31 sheet with a high Li content exhibited a high degree of dynamic recrystallization (DRX). Besides, the strain hardening rate of the annealed AZ31 sheets with a high Li content was more likely to be volatile, which can be attributed to Li atoms interacting with dislocations and influencing the movement of dislocations during the process of deformation. Furthermore, the Li addition to AZ31 alloy decreased the axial ratio ( c / a ) and led to a weak basal texture tilted towards the transverse direction (TD), and therefore improved the ductility and formability of the cold rolled and annealed AZ31 sheets. AZ31–3Li (LAZ331) sheet possessed excellent comprehensive mechanical properties and presented to be the best option in industrial processes considering the costing saving and property improvement. [ABSTRACT FROM AUTHOR]