Basal Orientation Research Articles

Understanding the mechanism of bimodal texture evolution and DRX behavior of AZ31 magnesium alloy during shear deformation

Shear deformation in commercial magnesium alloys frequently resulted in an additional atypical texture where the basal plane aligned nearly parallel to the extrusion direction, affecting the alloy's mechanical anisotropy. This study prepared AZ31 magnesium alloys with both typical shear texture and atypical texture using a two-stage shear method at 250 °C, 290 °C, and 340 °C. The formation mechanism of the bimodal texture and their relationship with dynamic grain refinement and deformation parameters were comprehensively investigated. While temperature-dependent activation of <c+a> slip usually contributed to the atypical texture, this study identified a {101¯2} twin associated microstructure that reinforced the abnormal texture at lower processing temperature. It was found that the abundant nucleation of the multi-orientation {101¯2} twin bands in the initial stage and their differential slip activations facilitated the evolution of an alternating banded structures characterized by bimodal texture. These microstructures inherited the grain boundary rotation axis of {101¯2} twin and was potentially assimilated into specialized θ[112¯0] symmetric tilt grain boundaries with lower interface energy during continuous shear, stabilizing the bimodal texture. During shear deformation, grain nucleation strengthened the [101¯0]−[112¯0] fibers with bimodal texture by generating ∼30°[0001] grain boundaries through the preferential accumulation of prismatic dislocations. However, more continuous dynamic recrystallization, discontinuous dynamic recrystallization, and micro-shear bands facilitated the nucleation of grains with dispersed basal orientations via dominant non-prismatic dislocations, weakening the overall texture. Besides, the mechanical anisotropy of the alloys was comprehensively influenced by atypical texture and microstructure. At higher deformation temperatures, the reduction in twinning bands and the increase in dynamic recrystallization level relieved the alloy’s tension-compression asymmetry, but deprived its yield strength. This study supplemented the formation mechanisms of bimodal texture during shear deformation, providing valuable insights for optimizing wrought magnesium alloys with superior mechanical properties.

Track-Rex: A universal toolbox for tracking recrystallization nucleation and grain growth behaviors in polycrystalline materials

Recrystallization annealing is widely used to tailor the microstructure and enhance the performance of cold-deformed metallic materials. However, the underlying recrystallization mechanisms are debated, even with the use of cutting-edge characterization techniques. Here, we develop a Track-Rex toolbox to analyze quasi-in-situ electron backscatter diffraction (EBSD) datasets of two magnesium (Mg) alloys during static recrystallization via grain correlation. The results show that the recrystallized grains do not always grow; instead, they can shrink or even be consumed. This is attributed to the presence of newly formed recrystallized grains that possess a growth advantage over the old recrystallized grains. The rare earth containing Mg-2.4Zn-0.2Ce wt.% (ZE20) alloy exhibits a higher nucleation activity in the shear bands compared to the commercial Mg-3Al-1 Zn (AZ31) alloy. Regardless of the nucleation timing and sites, recrystallized grains in the ZE20 alloy show consistent off-basal orientations, serving as the origin of the rare earth texture. Moreover, the off-basal texture of these recrystallized grains is further strengthened through preferential growth during subsequent annealing. On the contrary, the recrystallized grains in the AZ31 exhibit scattered basal orientations that grow uniformly, resulting in a weak basal texture.

The impact of the size and angle of the cochlear basal turn on translocation of a pre-curved mid-scala cochlear implant electrode

Scalar translocation is a severe form of intra-cochlear trauma during cochlear implant (CI) electrode insertion. This study explored the hypothesis that the dimensions of the cochlear basal turn and orientation of its inferior segment relative to surgically relevant anatomical structures influence the scalar translocation rates of a pre-curved CI electrode. In a cohort of 40 patients implanted with the Advanced Bionics Mid-Scala electrode array, the scalar translocation group (40%) had a significantly smaller mean distance A of the cochlear basal turn (p < 0.001) and wider horizontal angle between the inferior segment of the cochlear basal turn and the mastoid facial nerve (p = 0.040). A logistic regression model incorporating distance A (p = 0.003) and horizontal facial nerve angle (p = 0.017) explained 44.0–59.9% of the variance in scalar translocation and correctly classified 82.5% of cases. Every 1mm decrease in distance A was associated with a 99.2% increase in odds of translocation [95% confidence interval 80.3%, 100%], whilst every 1-degree increase in the horizontal facial nerve angle was associated with an 18.1% increase in odds of translocation [95% CI 3.0%, 35.5%]. The study findings provide an evidence-based argument for the development of a navigation system for optimal angulation of electrode insertion during CI surgery to reduce intra-cochlear trauma.

(Invited) Atomic Layer Processing of MoS2

Molybdenum disulfide (MoS2) is one of several transition metal dichalcogenides consisting of a layer of transition atoms sandwiched between layers of chalcogens. Interest in MoS2 has been driven by its 1.8 eV direct electronic band gap in monolayer form and its moderate electron mobility (10-100 cm2/Vs) even when only three atoms (~6.5 Å) thick. These properties offer potential for retaining or improving speed and efficiency in scaled electronic devices.Advancing MoS2 and other 2D materials into high volume manufacturing of semiconductor devices requires scalable deposition and etching processes. The process of atomic layer deposition (ALD) has been used to deposit 2D materials and can deposit films at lower temperatures for back-end-of-line (BEOL) compatibility. However, ALD relies on covalent surface reactions. When these reactions occur at high density during film nucleation, the resulting film is typically amorphous or nanocrystalline and requires thermal annealing to form a more well-ordered layered crystal structure. A key challenge is to establish a low temperature ALD process that achieves a layered crystal structure with low defectivity. In terms of material removal, MoS2 films have been etched by plasma-based atomic layer etching (ALE). ALE is analogous to ALD except that cyclic surface reactions promote volatility and lead to film removal rather than deposition. Together, atomic layer deposition and atomic layer etching constitute complementary facets of atomic layer processing and enable new pathways for nanomanufacturing.Here, we describe our recent progress in thermal ALD and thermal ALE of MoS2 films. For ALD of MoS2, we use cycles of MoF6 and H2S between 150-350 °C. Nucleation on metal oxide surfaces shows a strong temperature dependence, which is attributed in part due to the temperature dependence of surface hydroxyl groups. Density functional theory (DFT) calculations support the role of hydroxyls in promoting nucleation and reveal that MoF6 dissociates on the surface rather than participating in a ligand exchange reaction. The dissociation reaction leads to the formation of a metal fluoride interface between the oxide surface and the MoS2 film. Surface species following MoF6 include MoOF4 and MoO3, both of which convert to MoS2 during the H2S pulse, which releases H2O and HF byproducts. Films deposited at 200 °C and below are amorphous but convert to a layered structure upon annealing in H2S. Deposition at 250 °C yields films with a layered crystal structure without post-deposition annealing.Thermal ALE of MoS2 films deposited by ALD can be achieved using alternating exposures of MoF6 and H2O. It was found that MoS2 films are fluorinated by the MoF6 and then oxygenated by H2O. Volatile byproducts are MoF2O2, H2S, and HF, which are primarily released during the H2O half-cycle. Thermal ALE of MoS2 is temperature dependent and follows Arrhenius behavior. At 200 °C, the mass loss per cycle is 6 ng/cm2 (~0.5 Å/cycle) and reaches 271 ng/cm2 at 300 °C. Etch stop behavior was observed once the etched film approached the metal fluoride interface of the growth surface. Layered MoS2 deposited by ALD with post-deposition annealing exhibited layer-by-layer etching at 0.2 Å/cycle at 250 °C.The ALD results provide key insights into the nucleation and growth of MoS2 films using low temperature ALD. Further work is required to control basal plane orientation but achieving crystalline films well within BEOL thermal budgets is promising. The results from the ALE study provide insights into the etching reactions for MoS2. Combining the two processes offers greater control over MoS2 films. Using ALD followed by ALE and post-deposition annealing, we achieved few-layer MoS2 films. These combined thermal processes represent a pathway for integration of MoS2 films into device manufacturing.

Effects of hot rolling on the electrochemical behaviors and discharge performance of AZ61-In anodes for seawater activated batteries

In this research, corrosion behavior and discharge capabilities of the AZ61-In alloy experiencing hot rolling process have been discussed in detail. The results reveal that the introduction of indium to magnesium facilitates the dissolution of magnesium by augmenting a quantity of secondary phases, generating less-protective products. The corrosion resistance of AZI plus 50 % rolling reduction is improved attributed to the preferred basal orientation and further recrystallization. Moreover, the average discharge potentials of AZI-50 % can respectively reach −1.551 V and −1.234 V at 10 mA cm−2 and 50 mA cm−2, showing potential for application in seawater activated batteries.

LGN loss randomizes spindle orientation and accelerates tumorigenesis in PTEN-deficient epidermis.

Loss of cell polarity and disruption of tissue organization are key features of tumorigenesis that are intrinsically linked to spindle orientation. Epithelial tumors are often characterized by spindle orientation defects, but how these defects impact tumor formation driven by common oncogenic mutations is not fully understood. Here, we examine the role of spindle orientation in adult epidermis by deleting a key spindle regulator, LGN, in normal tissue and in a PTEN-deficient mouse model. We report that LGN deficiency in PTEN mutant epidermis leads to a threefold increase in the likelihood of developing tumors on the snout, and an over 10-fold increase in tumor burden. In this tissue, loss of LGN alone increases perpendicular and oblique divisions of epidermal basal cells, at the expense of a planar orientation of division. PTEN loss alone does not significantly affect spindle orientation in these cells, but the combined loss of PTEN and LGN fully randomizes basal spindle orientation. A subset of LGN- and PTEN-deficient animals have increased amounts of proliferative spinous cells, which may be associated with tumorigenesis. These results indicate that loss of LGN impacts spindle orientation and accelerates epidermal tumorigenesis in a PTEN-deficient mouse model.

Heterozygous FOXJ1 Mutations Cause Incomplete Ependymal Cell Differentiation and Communicating Hydrocephalus

Heterozygous mutations affecting FOXJ1, a transcription factor governing multiciliated cell development, have been associated with obstructive hydrocephalus in humans. However, factors that disrupt multiciliated ependymal cell function often cause communicating hydrocephalus, raising questions about whether FOXJ1 mutations cause hydrocephalus primarily by blocking cerebrospinal fluid (CSF) flow or by different mechanisms. Here, we show that heterozygous FOXJ1 mutations are also associated with communicating hydrocephalus in humans and cause communicating hydrocephalus in mice. Disruption of one Foxj1 allele in mice leads to incomplete ependymal cell differentiation and communicating hydrocephalus. Mature ependymal cell number and motile cilia number are decreased, and 12% of motile cilia display abnormal axonemes. We observed decreased microtubule attachment to basal bodies, random localization and orientation of basal body patches, loss of planar cell polarity, and a disruption of unidirectional CSF flow. Thus, heterozygous FOXJ1 mutations impair ventricular multiciliated cell differentiation, thereby causing communicating hydrocephalus. CSF flow obstruction may develop secondarily in some patients harboring FOXJ1 mutations.Graphical Heterozygous FOXJ1 mutations impair motile cilia structure and basal body alignment, thereby disrupting CSF flow dynamics and causing communicating hydrocephalus.

Effect of dynamic recrystallization, LPSO phase, and grain boundary segregation on heterogeneous bimodal microstructure in Mg-9.8Gd-3.5Y-2.0Zn-0.4Zr alloy

The formation conditions and influence mechanisms of the heterogeneous bimodal microstructure of Mg-9.8Gd-3.5Y-2.0Zn-0.4Zr alloy were systematically studied by thermal compression experiments in the range of 0.001–1.0 s−1 and 350–500 °C. Combined with the microstructural characterization, the inherent relationships between the grain structure and the deformation parameters are deeply analyzed. The results indicate that heterogeneous bimodal microstructures composed of fine dynamically recrystallized (DRXed) grains with random orientation and coarsely deformed grains with basal orientation can only be formed under deformation conditions of 40.51 < lnZ < 46.33. This mainly stems from the dominant continuous dynamic recrystallization (CDRX) and particle stimulated nucleation (PSN) mechanisms under this deformation condition. However, dynamic recovery (DRV) and discontinuous dynamic recrystallization (DDRX) dominate isothermal compression process with lnZ > 47.41 and lnZ < 39.74, which eventually lead to unimodal distributions of deformed grains and DRXed grains, respectively. Furthermore, results reveal that deformation parameters have a strong influence on the long-period stacking order (LPSO) phase and grain boundary (GB) segregation. The lamellar LPSO phases and grain boundary co-segregation of Zn, Y, and Gd atoms jointly promote CDRX and inhibit DDRX by preventing GB migration under the condition of 40.51 < lnZ < 46.33, which is ultimately beneficial to the development of heterogeneous bimodal Mg-Gd-Y-Zn-Zr alloy.

Improving the corrosion resistance of Mg-8Li-3Al-2Zn alloy by combining Gd alloying and hot extrusion

The microstructure and corrosion behavior of Mg-8Li-3Al-2Zn(−1.0Gd) alloys were investigated. In as-homogenized LAZ832(−1.0Gd) alloys, galvanic corrosion occurs at α-Mg/β-Li phase interface, and pitting corrosion occurs in α-Mg matrix and β-Li matrix. After hot extrusion, the corrosion form of α-Mg matrix changes to intergranular corrosion. The corrosion resistance of LAZ832 alloy is effectively improved by combining Gd alloying and hot extrusion, and as-extruded LAZ832–1.0Gd alloy exhibits the best corrosion resistance with a corrosion rate of 0.64 mm·y−1. Gd alloying improves corrosion resistance mainly due to the formation of Al2Gd phase, the reduction of AlLi phase, and the formation of oxide film containing Gd2O3. Hot extrusion improves corrosion resistance mainly attributed to the increase in the share of basal orientation and the crushing of fibrous AlLi phase.

Heterogeneous bimodal microstructure and its formation mechanism of Mg-Gd-Y-Zn-Zr alloy during isothermal compression

Heterogeneous bimodal microstructure and its formation mechanism of Mg-Gd-Y-Zn-Zr alloy during isothermal compression at 450 °C and 0.001 s−1 was investigated in detail. Based on microstructure analysis, Mg-Gd-Y-Zn-Zr alloys with bimodal grain size distribution and bimodal texture distribution were obtained by uniaxial isothermal compression. There were more heavily bimodal levels in grain size and texture at true strain greater than 0.8. There was a significant inhomogeneous plastic deformation between and within the grains in Mg-Gd-Y-Zn-Zr alloy during the deformation, which is attributed to the difference the grain orientation and a large number of intergranular block-shaped LPSO phases. Further studies revealed that particle-stimulated nucleation (PSN) caused by a large intergranular LPSO phases and continuous dynamic recrystallization (CDRX) developed layer by layer toward the grain interior were the main grain refinement mechanisms. This PSN and CDRX mechanism contributed to the fine grains in bimodal grain size distribution and the random texture in bimodal texture distribution. However, the original coarse grains with basal orientation were preserved during deformation due to smaller plastic deformation and energy storage. Meanwhile, grain boundary segregation and intragranular lamellar LPSO precipitate promoted CDRX by retarding DDRX. In addition, the grain boundary pinning effect dominated by grain boundary segregation and intragranular lamellar LPSO precipitate hindered the coarsening of fine DRXed grains, which was the ultimate guarantee for the formation of bimodal microstructure. Ultimately, inhomogeneous plastic deformation, DRX, and grain boundary pinning effect were demonstrated as the necessary conditions for the formation of heterogeneous bimodal microstructure during thermal deformation of Mg-Gd-Y-Zn-Zr alloy.

Study on localized corrosion behavior of hot extrusion deformed GW103K magnesium alloy

This study investigated the corrosion behavior in the core and at the edge of the cross-section of an extruded GW103K (Mg–10Gd–3Y–0.4Zr) alloy. Equivalent stress and strain were modeled using finite element simulations. The stress and strain in the core were lower than those at the edge. The microstructure, corrosion morphology, and grain orientation of the alloy were examined using optical microscopy, scanning electron microscopy, and electron backscatter diffraction, respectively. The results showed that most grains in the core exhibited a basal plane orientation and lower surface energy, whereas those at the edge exhibited cylindrical orientations. Hydrogen evolution experiments and electrochemical tests showed that the corrosion resistance in the core was higher than that at the edge. Scanning Kelvin probe force microscopy measurements of the surface potential distribution in the cross-section revealed a large potential difference between the second-phase particles at the edge and the matrix, with obvious galvanic corrosion. The alloy core exhibited low stress and a higher content of grains with basal plane orientation, along with a small potential difference between the second-phase particles and the matrix. Thus, the corrosion resistance in the core was higher than that at the edge.

On rate dependence and anisotropy in phase field modeling of polycrystalline fracture

A phase field theory of fracture incorporating rate dependence (i.e., kinetic viscosity) and anisotropic elasticity is implemented to study strength and failure modes in polycrystalline materials. After presentation of the constitutive framework, a new analytical solution is derived for one-dimensional (1D) homogeneous loading at constant strain rate, wherein crack viscosity is enabled. The three-dimensional (3D) theory is implemented in a finite element (FE) context, with static and dynamic solutions verified up to peak loading for homogeneous microstructures. Extensive simulations of heterogeneous polycrystalline microstructures follow, where baseline material properties correspond to either boron carbide (B4C) or titanium diboride (TiB2). Results quantify effects of loading rate, elastic anisotropy, cleavage energy anisotropy, and grain boundary surface energy on tensile strength. Notable are effects of strong basal texture, which influences average strength via both elastic anisotropy and basal cleavage plane orientation. Effects of loading rate are naturally more prominent for materials that fail mostly intergranularly rather than transgranularly, in agreement with experimental observations.

High-Sensitivity Low-Energy Ion Spectroscopy with Sub-Nanometer Depth Resolution Reveals Oxidation Resistance of MoS2 Increases with Film Density and Shear-Induced Nanostructural Modifications of the Surface.

For decades, density has been attributed as a critical aspect of the structure of sputter-deposited nanocrystalline molybdenum disulfide (MoS2) coatings impacting oxidation resistance and wear resistance. Despite its importance, there are few examples in the literature that explicitly investigate the relationship between the density and oxidation behaviors of MoS2 coatings. Aging and oxidation are primary considerations for the use of MoS2 coatings in aerospace applications as they inevitably experience prolonged storage in water and oxygen-rich environments prior to use. Oxidation that is either limited to the first few nanometers or through the bulk of the coating can result in seizure due to high initial coefficients of friction or component failure from excessive wear. High-sensitivity low-energy ion spectroscopy (HS-LEIS) and Rutherford backscattering spectrometry (RBS) are both used to understand the extent of oxidation throughout the first ∼10 nanometers of the surface of pure sputtered nanocrystalline MoS2 coatings after high-temperature aging and how it is impacted by the density of coatings as measured by RBS. Results show that low-density coatings (ρ = 3.55 g/cm3) exhibit a more columnar microstructure and voiding, which act as pathways for oxidative species to penetrate and interact with edge sites, causing severe surface and subsurface oxidation. Furthermore, HS-LEIS of surfaces sheared prior to oxidation reveals that the oxidation resistance of low-density MoS2 coatings can be significantly improved by shear-induced reorientation of the surface microstructure to a basal orientation and elimination of pathways for oxygen into the bulk through compaction of surface and subsurface voids.

Synthesis of thin single-crystalline α-Cr-=SUB=-2-=/SUB=-O-=SUB=-3-=/SUB=- layers on sapphire substrates by ultrasonic-assisted chemical vapor deposition

Single-crystalline α-Cr2O3 layers were synthesized on a sapphire substrate with a basal orientation in a laboratory reactor using ultrasonic-assisted chemical vapor deposition in the temperature range of 700-850oC. The influence of the growth temperature on the structural quality of the layer was studied by X-ray diffraction. At a growth temperature of 800oC, continuous layers with a thickness of about 1 μm were obtained. The layers were transparent in the visible region with a slightly greenish tint and showed some light transmission up to wavelengths of ~ 350 nm. The full width at half maximum of the rocking curve for reflection 0006 was ~ 300 arcsec. Keywords: chromium oxide, CVD epitaxy, wide-bandgap semiconductor.

Тонкие монокристаллические слои &amp;alpha;-Cr-=SUB=-2-=/SUB=-O-=SUB=-3-=/SUB=-, выращенные на подложках сапфира в реакторе ультразвуковой паровой химической эпитаксии

Single-crystalline α-Cr2O3 layers were synthesized on a sapphire substrate with a basal orientation in a laboratory reactor using ultrasonic-assisted chemical vapor deposition in the temperature range of 700-850°C. The influence of the growth temperature on the structural quality of the layer was studied by X-ray diffraction. At a growth temperature of 800°C, continuous layers with a thickness of about 1 μm were obtained. The layers were transparent in the visible region with a slightly greenish tint and showed some light transmission up to wavelengths of ~350 nm. The full width at half maximum of the rocking curve for reflection 0006 was ~ 300 arcsec.

Template-free scalable growth of vertically-aligned MoS2 nanowire array meta-structural films towards robust superlubricity.

Two-dimensional (2D) molybdenum disulfide exhibits a variety of intriguing behaviors depending on its orientation layers. Therefore, developing a template-free atomic layer orientation controllable growth approach is of great importance. Here, we demonstrate scalable, template-free, well-ordered vertically-oriented MoS2 nanowire arrays (VO-MoS2 NWAs) embedded in an Ag-MoS2 matrix, directly grown on various substrates (Si, Al, and stainless steel) via one-step sputtering. In the meta-structured film, vertically-standing few-layered MoS2 NWAs of almost micron length (∼720 nm) throughout the entire film bulk. While near the surface, MoS2 lamellae are oriented in parallel, which are beneficial for caging the bonds dangling from the basal planes. Owing to the unique T-type topological characteristics, chemically inert Ag@MoS2 nano-scrolls (NSCs) and nano-crystalline Ag (nc-Ag) nanoparticles (NPs) are in situ formed under the sliding shear force. Thus, incommensurate contact between (002) basal planes and nc-Ag NPs is observed. As a result, robust superlubricity (friction coefficient μ = 0.0039) under humid ambient conditions is reached. This study offers an unprecedented strategy for controlling the basal plane orientation of 2D transition metal dichalcogenides (TMDCs) via substrate independence, using a one-step solution-free easily scalable process without the need for a template, which promotes the potential applications of 2D TMDCs in solid superlubricity.

Theoretical analysis of interfacial design and thermal conductivity in graphite flakes/Al composites with various interfacial coatings

Abstract Graphite flakes/Al composites are promising thermal management materials due to high thermal conductivity (TC) in basal plane orientation, matched coefficient of thermal expansion, and good machinability. In this article, the acoustic mismatch model and the effective medium approach are applied to predict the influence of different interfacial coatings on the interfacial thermal conductance (ITC) and the TC of graphite flakes/Al composites, respectively. With the increase in the thickness of interfacial coatings, the ITC and the TC of graphite flakes/Al composites decrease. For the composites with Ni, Cr/Cr7C3/Cr3C2, Si/SiC, Ti/TiC, WC, and Mo/Mo2C coatings, the ITC is sensitive to coating thickness. In order to obtain ideal TC of graphite flakes/Al composites, the thickness of the coatings should be controlled below 1 μm. It is reasonable that the TC of the graphite flakes/Al composites increases as the volume fraction of graphite flakes increases. The TC of the graphite flakes/Al composites increases with the ITC and changes slowly when the ITC increases to a certain extent. Si/SiC and WC coatings are proposed to be the most promising candidates to improve the thermal performance of graphite flakes/Al composites.

Ameliorating the edge cracking behavior of Mg-Mn-Al alloy sheets prepared by multi-pass online heating rolling

Low-cost Mg-1Mn-0.5Al (MA10) alloys with good comprehensive strength and ductility have been developed and have the potential to substitute commercial AZ31 alloys. Thus, the rollability in terms of the edge cracking behavior of MA10 alloy sheets was investigated by multi-pass online heating rolling at different temperatures. The microstructure evolution was characterized by scanning electron microscopy (SEM), electron backscatter diffraction (EBSD) and transmission electron microscopy (TEM). The results reveal that edge cracking is significantly improved with increasing temperature due to the more uniform microstructure, higher degree of recrystallization, more homogeneous strain distribution, and more activation of non-basal slips at the edge. The maximum basal texture intensity at the edge of MA10 rolled sheets is obviously increased with increasing temperature, which can be attributed to the increased numbers of grains with basal orientation after multi-pass online heating rolling.

Enhancement of the mechanical properties of textured AZ31 Mg alloy sheets by bimodal-orientation microstructure: Basal orientation and RD-texture

In the present study, a bimodal-orientation microstructure including the basal orientation and RD-texture was prepared by twinning deformation of an AZ31 Mg alloy sheet. Experimental results show that 21%–24% of tension twin boundaries are produced and that the recrystallization content decreased by up to 30.5%–52.0% after hot deformation. The variant selections of island twin and parallel tension twin pairs conform to the Schmid law, while the connected twin pairs and the twin transmitting are controlled by the strain coordination. Twin-free grains are observed because of the accommodation strain controlled by the hard deformation mode. After final post-annealing, the bimodal-orientation microstructure is balanced with a tension twin boundary fraction and recrystallization content of 16.6%–22.2% and 45.0%–74.3%, respectively. Finally, the anisotropy weakening, and improvement of formability are obtained due to the orientation adjustment and work hardening elimination, with the average Lankford values (r‾) decreasing from 2.84 to 0.43 and the IE value increasing from 2.25 to 4.63.

Unveiling the rolling texture variations of α-Mg phases in a dual-phase Mg-Li alloy

LZ91 Mg-Li alloy plates with three types of initial texture were rolled by 70% reduction at both room temperature and 200 °C to explore the rolling texture formation of α-Mg phase. The results showed that the rolling texture is largely affected by the initial texture. All the samples exhibited two main texture components as RD-split double peaks texture and TD-split double peaks texture after large strain rolling. The intensity of the two texture components was strongly influenced by the initial orientation and rolling temperature. Extension twinning altered the large-split non-basal orientation to a near basal one at low rolling strain. The basal orientation induced by twinning is unstable, which finally transmitted to the RD-split texture. The strong TD-split texture formed due to slip-induced orientation transition from its initial orientation. The competition between prismatic 〈a〉 and basal slip determined the intensity and tilt angle of the TD-split texture. By increasing the rolling temperature, the TD-split texture component was enhanced in all three samples. Limitation of extension twinning behavior and the promotion of prismatic slip at elevated temperature are the main reasons for the difference in hot and cold rolling texture.