Texture Evolution Of Mg Research Articles

Effect of Al addition and rolling reduction on microstructure and texture evolution of Mg–3Sn alloy during high-speed rolling

Effect of Al addition and rolling reduction on microstructure and texture evolution of Mg–3Sn alloy during high-speed rolling

Effect of pre-aging on microstructure, activation energy, texture evolution of Mg–9Gd–4Y–2Zn–0.5Zr alloy during compression deformation

This paper illustrated the effects of pre-aging on the microstructure, texture evolution, and deformation behavior of Mg–9Gd–4Y–2Zn–0.5Zr alloy during hot compression. Dynamic recrystallization (DRX) behavior, texture evolution, stress-strain curve, and activation energy of the solid solution and pre-aged alloy were evaluated. The results showed that the second-phase particles of the pre-aged samples exhibit combination of two types particles structure, which is composed of coarse dynamic precipitation particles and fine nanoparticles. The combination of these two types particles showed the best grain refinement effect by accelerating the DRX process, as the coarse dynamic precipitation particles promoted DRX through the PSN mechanism and the fine granular phase pinned dislocations and inhibited grain growth. As a result, the pre-aged samples had a higher DRX grain volume fractions and smaller average grain sizes than the solid solution alloys. In addition, the pre-aged sample had higher deformation activation energy (Q = 294.8 kJ/mol) than solid solution sample (Q = 223 kJ/mol) because β-phase pin dislocations formed during deformation restrained the movement of grain boundaries. The pre-aged alloys also showed a more concentrated texture than the solid solution alloys, with the c-axis of the coarse grains distributed from the compression direction (CD) at 30° inclination to the normal direction (ND). The c-axis distribution of the coarse grains was more scattered in the solid solution alloys. A hot processing map was constructed for the pre-aged alloy and used for evaluation. The optimal deformation parameters for the pre-aged Mg–9Gd–4Y–2Zn–0.5Zr alloy were between 0.001 and 0.1 s−1 at 400 °C–480 °C. These significant observations not only provide theoretical guidance but also practical application for setting plastic forming deformation parameters in industrial production.

The hot deformation behavior, microstructure and texture evolution of homogenized Mg–9Li–1Zn alloy

In this study, the hot deformation behavior, microstructure and texture evolution of Mg–9Li–1Zn (LZ91) alloy were investigated systematically, and the best Arrhenius hot deformation constitutive equation model and processing map of the LZ91 alloy were developed. Hot compression tests were performed at deformation temperatures and strain rates ranging from 175 °C to 275 °C and 0.001 s−1 to 1 s−1, respectively. The results showed that Arrhenius constitutive equation can predict accurately the hot deformation behavior of LZ91 alloy. The instability areas for this alloy were concentrated in the range of 175 °C–220 °C, 0.01 s−1–0.1 s−1 and 225 °C–260 °C, 0.001 s−1–0.002 s−1 and 0.02 s−1–1 s−1. The observation of microstructure revealed that the alloy is deformed by the cooperation of the basal slip system and the pyramidal conical slip system. In addition, the hardness which increases in a gradient from the center to the edges is the result of the combined effect of grain refinement and texture.

Dynamic Recrystallization Behaviors and the Texture Evolution in Mg–9Al–1Zn Alloy Produced by ECAP at Different Temperatures

Dynamic Recrystallization Behaviors and the Texture Evolution in Mg–9Al–1Zn Alloy Produced by ECAP at Different Temperatures

Understanding the Texture Evolution in Mg and its Alloys During Hot Deformation

Understanding the Texture Evolution in Mg and its Alloys During Hot Deformation

Understanding the Texture Evolution in Mg and its Alloys During Hot Deformation

Understanding the Texture Evolution in Mg and its Alloys During Hot Deformation

Texture evolution in Mg during rolling with a change of deformation path - a modeling approach

Texture evolution in Mg during rolling with a change of deformation path - a modeling approach

Dynamic Precipitation, Dynamic Recrystallization, and Texture Evolution of Mg-5Zn Alloy Sheets with Trace Ca and Sr Additions.

The effects of trace Ca and Sr addition on dynamic precipitates, dynamic recrystallization (DRX) behavior, and texture evolution of Mg–5Zn alloy sheets fabricated by high strain rate rolling (HSRR) were investigated by electron backscattered diffraction (EBSD), transmission electron microscopy (TEM), small-angle X-ray scattering (SAXS), and X-ray diffraction (XRD). The Zn-rich precipitates formed with plate shapes, short-rod shapes, and near-spherical shapes, indicating that the most important function of adding Ca and Sr is to promote the precipitation process. The precipitate density increases, but the precipitate size and DRX volume fraction decrease with the addition of the alloying elements. It is concluded that the effects of combined Ca/Sr addition on promoting precipitation and refining precipitate size are more effective than that of single Ca addition, and the reduction in DRX volume fraction can be attributed to the inhibition of fine precipitation on the nucleation and growth of DRX. Moreover, the macro-texture intensity is mainly related to DRX as the DRX grains are much more randomly oriented than deformed grains. In addition, the texture intensity in DRX regions is primarily associated with the precipitates, which can inhibit DRX grain rotation due to their pinning effect on the grain boundaries.

Microstructure, Mechanical Properties and Texture Evolution of Mg–Al–Zn–La–Gd–Y Magnesium Alloy by Hot Extrusion and Multi-Pass Rolling

A high-ductility Mg–8.10Al–0.42Zn–0.51Mn–1.52La–1.10Gd–0.86Y (wt%) alloy was developed by hot extrusion and multi-rolling processes. Relationships between microstructure, mechanical properties and texture evolution of the extruded and rolled alloy were investigated. The rolling process had significant effect on grain refinement of the extruded plate. The grain size reduced from 12.3 to 4.9 μm with the increasing rolling pass. With the increase in rolling pass, the proportion of dynamic recrystallized (DRXed) grains increases due to particle-stimulated nucleation, grain boundary nucleation and twin induced nucleation. In the process of multiple rolling, the basal pole gradually tilted from normal direction to transverse direction due to the asymmetric deformation and irregular grain deformation, resulting in the weakening of the base texture. The results showed that grain refinement and texture weakening were the main reasons for the good ductility of the alloy.

Microstructure and Texture Evolution of Mg-Gd-Y-Zn-Zr Alloy by Compression-Torsion Deformation.

Mg–13Gd–4Y–2Zn–0.5Zr alloy was subjected to compression–torsion deformation at 450 °C with a strain rate of 0.001–0.5 s−1 using a Gleeble 3500 torsion unit. The effects of compression–torsion deformation on the microstructure and texture were studied, and the results showed that with the decrease of strain rate, the texture strength decreased, the number of dynamic precipitated particles increased, the degree of recrystallization increased, and the dynamic recrystallization mechanism changed from a continuous dynamic recrystallization mechanism to a continuous and discontinuous dynamic recrystallization mechanism. Along the direction of increasing radius, the degree of dynamic recrystallized grain (DRX) increased, the number of dynamic precipitated particles increased, and the texture strength slightly increased.

Microstructure, mechanical properties, and texture evolution of Mg–Zn–Y–Zr alloy fabricated by hot extrusion–shearing process

In this study, ultrafine-grained Mg–Zn–Y–Zr alloys were obtained via a novel extrusion–shearing (ES) deformation process, which combined initial forward extrusion with subsequent shearing. The experimental results showed that the composition of the main phase was converted from the α-Mg, I (Mg3Zn6Y), and W (Mg3Zn3Y2) phases to the α-Mg and W phases as the Zn/Y mass ratio of the as-cast alloys decreased from 4 to 0.67. Needle-shaped YZn5 and micron-sized Mg7Zn3 phases were also observed in the as-homogenized Mg–4Zn–1Y–0.6Zr and Mg–3Zn–2Y–0.6Zr alloys. The quantitative electron backscatter diffraction results demonstrated that the dynamic recrystallization (DRX) and the growth of fine DRX grains had a strong dependence on the equivalent strain and increased temperature caused by the die corner. The abundance of W precipitates resulted in the gradual evolution of the sub-grains into fresh DRX grains for the ES alloy III. Additionally, reduced strength anisotropies were related to the decreased pole density caused by the increasing addition of Y; a weakened basal texture with a rare-earth texture component was also achieved at 3 wt% of Y addition. Finally, the influences of the grain size and basal texture on the ductility and strength of the ES alloys were systematically investigated.

Effect of shear deformation on plasticity, recrystallization mechanism and texture evolution of Mg–3Al–1Zn alloy sheet: Experiment and coupled finite element-VPSC simulation

Microstructure characterization and texture evolution of multi-passes isothermal symmetry and asymmetry rolling, or namely differential speed rolling (DSR), of Mg–3Al–1Zn alloy sheets were systematically investigated at different temperatures and strain levels. Also, two scale model coupling finite element and a visco-plastic self-consistent model (FE-VPSC) was employed. Results indicate that the predominant dynamic recrystallization (DRX) mechanism transits from twinning DRX at 150 °C to continuous DRX at 250 °C attributed to the distinctively activated deformation modes. It was found that shear deformation induced in DSR plays a crucial role on the activation of deformation modes and related DRX mechanisms. Based on the calculation of effective Schmid factor (ESF), shear deformation is believed to promote the activation of contraction twinning and pyramidal <c+a> slip by increasing their ESFs. Furthermore, the concentration of grain orientations caused by profuse operation of basal <a> slip can facilitate the activation of twinning and pyramidal <c+a> slip during DSR. As a result, twinning DRX dominated region was obviously enlarged owing to a larger fraction of twinning at low temperature (<200 °C). Meanwhile, profuse activation of pyramidal <c+a> slip at high temperature (>200 °C) can accelerate the continuous DRX. After annealing at 250 °C for 1 h, fine grains with an average size of 3.36 μm and a large basal titled angle (∼26°) were attained for the twinning DRX controlled sheet at 150 °C.

Effect of Asymmetric Rolling on the Microstructure, Mechanical Properties and Texture Evolution of Mg–8Li–3Al–1Y Alloy

Asymmetric rolling was applied to dual phase Mg–8Li–3Al–1Y alloy with different speed ratio and rolling reduction. With increasing reduction at the same speed ratio the population of β-Li grains decreased with a feature of fibered grains along the rolling direction. As for different speed ratio under the same reduction, β-Li grains kept equiaxed, but α-Mg phase was first elongated and fibered and then transited to equiaxed small grains. The enhanced yield strength and tensile strength were achieved with the increase of rolling reduction and speed ratio. In particular, when speed ratio reached to 1:1.3 under the same rolling reduction (30%), the optimal mechanical properties were obtained. As for texture evolution, we found the basal texture was obviously weakened and some new weak texture was formed after asymmetric rolling. Interestingly, it was noted that the texture on the side of slow roll is distinct from that on the side of the fast roll due to the different rolling speed.

Effects of repetitive upsetting-extrusion parameters on microstructure and texture evolution of Mg–Gd–Y–Zn–Zr alloy

Repetitive upsetting-extrusion (RUE), a severe plastic deformation, was performed on the Mg-12.0Gd-4.5Y-2.0Zn-0.4Zr (wt %) alloy at different deformation temperatures in the range of 693–773 K for 1, 2 and 3 passes. The study was aimed to determine the effects of deformation temperatures and processing passes of RUE on the microstructure and texture evolution of the RUEed alloy. It is found that dynamic recrystallization (DRX) occurred in the alloy and β- Mg5(Gd,Y,Zn) phase particles precipitated at grain boundaries during the RUE processing. The microstructure was refined remarkably during RUE, the microstructure distribution became more homogeneous and the degree of DRX was increased with the number of the processing passes increasing. The grain refinement was mainly caused by DRX, and the LPSO phases stimulated the DRX around the grain boundaries via particle stimulation nucleation mechanism. The microstructure and texture evolution were mainly depended on the RUE processing parameters, such as processing passes and deformation temperatures. The basal texture was gradually weakened during more processing passes and higher deformation temperatures of RUE processing. The microstructure and texture evolution of the alloy were affected more by processing passes than deformation temperatures during RUE. After 3 RUE passes, some (0001) basal planes were perpendicular to the ED and that also were parallel to the ED in some grains, which is different from that observed in both extruded alloys and other plastically deformed counterparts. The number fraction of low angle grain boundaries tended to decrease while the average misorientation angles tended to increase with the processing passes and deformation temperatures of the RUE increasing.

On the texture evolution of Mg–Zn–Ca alloy with different hot rolling paths

Abstract In the present study, the texture evolution and mechanical anisotropy in a typical Mg–Zn–Ca alloy through hot cross rolling (CR) and unidirectional rolling (UR) were systematically studied. The results show that the rolling path greatly affects the annealed texture. The UR develops a texture with basal poles mainly distributing along the transverse direction (TD). By contrast, an ellipse-like (0002) texture with basal pole inclining largely away from the normal direction (ND) is developed after hot cross rolling and annealing. Therefore, the CR is an effective method to tailor the texture of the experimental alloy. Unfortunately, this ellipse-like texture could not reserve during the subsequent unidirectional hot rolling and annealing. Both UR and CR plates exhibit a strong planar mechanical anisotropy compared with the traditional unidirectional rolled plate.

Microstructure and texture evolution of Mg–7Y–1Nd–0.5Zr alloy sheets with different rolling temperatures

The extruded Mg–7Y–1Nd–0.5Zr (wt%) alloy were performed to the same strain hot rolling with different temperatures. The microstructure and texture evolution of the sheets were investigated by optical microscopy (OM), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and electron back-scattered diffraction (EBSD). The results indicate that the microstructure becomes homogeneous after hot rolling process and precipitated phase distributes at grain boundaries along rolling direction. With the increase in rolling temperature, the grains of sheet grow up. The sheet rolling at 400 °C is composed of recrystallization grains, the necklace of the precipitated phase in the grain boundaries and excessive dislocations. The structure of necklace of the precipitated phase is fcc structure with lattice constant of a = 0.75 nm. With rolling temperatures increasing from 400 to 450 °C, the content of recrystallized grains in volume fraction with relatively random orientations increases significantly. Compared with the rolling process at 400 °C, the amount of precipitated phases is reduced at the grain boundary, and the precipitated phase begins to appear in the grain interior when rolling at 450 °C. The structure of the precipitated phase is fcc with lattice constant of a = 2.22 nm. The recrystallization grains begin to grow in the rolling process at 500 °C. The basal texture is obviously produced during the rolling process at 400 and 450 °C; however, the basal texture is weak in the rolling process at 500 °C. The pole point of the (0002) pole figure is concentrated in the center. It can be seen that the basal surface is parallel to RD–TD surface of the rolling sheets. Compared with as-extruded alloy, the basal texture is significantly enhanced with a small increase in basal texture intensity from 6.127 to 7.175, and $$(10\bar{1}0)$$ and $$(11\bar{2}0)$$ textures change to random textures.

Mg–3Al–1Zn alloy strips processed by electroplastic differential speed rolling

The effect of reduction per pass on the mechanical properties, microstructure and texture evolution of Mg–3Al–1Zn magnesium alloy strips processed by electroplastic differential speed rolling has been investigated. With increasing reduction per pass, the mechanical properties of the rolled strips increase. Both the shear effect and the current pulses play an important part in modifying the microstructure and texture by promoting dynamic recrystallisation. During dynamic recrystallisation, nucleus tends to nucleate in the vicinity of the shear bands. And as the progress of dynamic recrystallisation, shear bands are gradually consumed by the newly nucleated grains and become nearly indistinguishable. The athermal effect of current pulses plays an important role in promoting dynamic recrystallisation.

Relationship between textures and deformation modes in Mg–3Al–1Zn alloy during uniaxial tension

The effects of initial texture on the flow behavior, microstructure and texture evolution of Mg–3Al–1Zn alloy hot rolled plate with a strong basal texture during tension at room temperature have been investigated by experiments and simulations. Three kinds of specimens were cut from this plate with their tensile directions aligned 0°, 45°, and 90° to the normal direction (ND), and they were referred as 0ND, 45ND and 90ND specimens, respectively. A crystal plasticity model was developed to demonstrate the relationship between textures and deformation modes. The results show that the general features of flow curves and texture evolutions of AZ31 alloy during tension can be well explained by the relative activities of deformation modes, which exhibit a pronounced orientation dependence on both the starting and current textures. The obvious yielding behaviors in 0ND and 45ND specimens are induced by the initial activity of {10–12} twinning, and the strain hardening behavior is related to the activities of {10–12} twinning, basal slip and prismatic slip. Due to the existence of {10–11} twinning at low strain, the elongation to rupture of 90ND specimen is much lower than those the elongation of 0ND and 45ND specimens. Although prismatic slip activity depends on the initial texture, its activities always increases during tension, affecting the flow curves, microstructure and texture evolutions. The high prismatic slip activities in 0ND and 90ND specimens result in a strong {10–10} prismatic texture, while the activity of pyramidal <c+a> slip is always negligible in all specimens and insensitive to the initial texture during tension.

Microstructure and texture evolution in Mg–Al–Zn–(AgIn) alloy during single and multiple pass warm rolling

Abstract

Microstructure and texture evolution of Mg–Li alloy during rolling

Abstract This paper investigates the microstructure and texture evolution of as-rolled Mg-5Li-3Al-2Zn-1.2Y-0.8Nd. During rolling (both warm rolling and hot rolling), many twins appear in the alloy, some of which are cross-twins. Dynamic recrystallization occurs, resulting in grain refinement. With the increase of rolling reduction percentage, basal texture appears, and then finally non-basal texture appears. The non-basal texture during warm rolling begins to appear under a smaller rolling reduction percentage than that during hot rolling. When the rolling reduction is 28 %, the angles between the majority of c-axes and rolling direction are mainly about 25°. When the rolling reduction percentage is 52 %, the textures are strengthened.