Mechanism Of Texture Formation Research Articles

The Role of Deformation and Microstructure Evolution on Texture Formation of a TA15 Alloy Subjected to Plane Strain Compression

In this study, the texture formation mechanism of a TA15 titanium alloy under different plane strain compression conditions was investigated by analyzing the slipping, dynamic recrystallization (DRX) and phase transformation behaviors. The results indicated that the basal texture component basically appears under all conditions, since the dominant basal slip makes the C-axis of the α grain rotate to the normal direction (ND, i.e., compression direction), but it has a different degree of deflection. With an increase in deformation amount, temperature or strain rate, {0001} poles first approach the ND and then deviate from it. Such deviation is mainly caused by a change in slip behaviors and phase transformation. At a smaller deformation amount and higher strain rate, inhomogeneous deformation easily causes a basal slip preferentially arising from the grain with a soft orientation, resulting in a weak basal texture component. A greater deformation amount can increase the principal strain ratio, thereby promoting other slip systems to be activated, and a lower temperature can increase the critical shear stress of the basal slip, further causing a dispersive orientation under these conditions. At a higher temperature and a lower strain rate, apparent phase transformation will induce the occurrence of lamellar α whose orientation obeys the Burgers orientation of the β phase, thereby disturbing and weakening the deformation texture. As for DRX, continuous-type (CDRX) is most common under most conditions, whereas CDRX grains have a similar orientation to deformed grains, so DRX has little effect on overall texture. Moreover, the microhardness of samples is basically inversely proportional to the grain size, and it can be significantly improved as lamellar α occurs. In addition, deformed samples with a weaker texture present a higher microhardness due to the smaller Schmidt factors of the activated prism slip at ambient loading.

Calculation of the CRSS ratios of Ti80 alloy and its application in prediction of texture in Pilger cold rolling

The accurate critical resolved shear stress (CRSS) ratios of different slip systems and deformation history are vital for the texture simulation and controlling for Ti80 alloy pipe during Pilger cold rolling process. This study proposed a comprehensive framework for determining these parameters. A method to calculate the CRSS ratio based on the statistics of activated slip systems was proposed, which could effectively eliminate the error of activated slip systems proportion caused by microtexture. No twinning was observed in the deformation of Ti80 alloy, and the activated slip systems of {0002}<11 2‾ 0>, {101‾ 0}<112‾ 0>, {101‾ 1}<112‾ 0> and {112‾ 2}<112‾ 3> were observed through uniaxial in-situ tensile test combined with EBSD at room temperature. And the CRSS ratio of Ti80 alloy has been calculated approximately as τBasal<a>: τPrism<a>: τPyram<a>: τPyram<a> = 1:0.8:3.5:6. Based on visco-plastic self-consistent (VPSC) model and the calculated CRSS, the texture with shear strain and without shear strain was simulated respectively in the Pilger cold rolling process. Meanwhile, the mechanism of texture formation was analyzed. The texture component was [0001] ‖ TD, and [11-20]‖ AD when the traditional velocity gradient neglecting shear strain was adopted in simulation. However, the shear strain in ZR direction would cause the texture to rotate 30° around the [0001] axis. Compared with that only considering the velocity gradient in the normal strain direction, the rolling texture can be more accurately predicted when considering the history of velocity gradient in all directions.

Analysis of the texture evolution during multipass tube spinning of a TA15 alloy using the crystal plasticity finite element model

In this study, we present an explicit crystal plasticity finite element model (CPFEM) to investigate the texture evolution during multipass tube spinning of a TA15 alloy. The texture formation mechanism is further revealed by analyzing grain rotation and slip behaviors. The results indicate that, for the grains whose c-axes are far from the normal direction (ND), the basal <a> slip is dominant under the significant compression deformation state of spinning. Therefore, the c-axis gradually turns toward the ND. However, for the grains whose c-axes are close to the ND, the contribution ratios of other slip systems increase, especially that of prism <a>. Under these conditions, the c-axis deviates slightly from the ND, and grains mainly rotate around the c-axis. Therefore, most of the {0001} poles cluster around the ND and {10-10} poles are distributed in the rolling-hoop plane, exhibiting an obvious basal texture component. These results imply that the CPFEM can effectively predict the formation of basal texture component during spinning. With an increase in the number of spinning pass, the texture distribution becomes slightly inhomogeneous along the ND owing to the uneven distribution of macroscopic strain. In addition, the grain rotation first increases and then decreases with deformation. The smaller grain rotation at the first pass is because a large number of basal <a> preferentially operates in the grain with favorable orientation, resulting in localized inhomogeneous deformation. The decrease at larger deformation is due to the lower Schmidt factor of basal <a>, which limits the grain rotation.

Microstructure and texture development during annealing in UF340

UF340 is a new type of cold-rolled fine grain high-strength steel with excellent formability developed by Shougang Co., Ltd Company. In this paper, the formation mechanism of recrystallisation texture of UF340 during annealing at 720 °C were systematically investigated. The as-received cold rolled sheet displayed a pronounced α-fiber texture together with a weak γ-fiber texture. With increasing annealing time, recrystallization occurred in the elongated grains, γ-fiber texture grains generated and grew up gradually. The texture component of the original α-fiber grains shift toward {112} <110>, {023} <100>, {223}<352> and finally {111} <112>. High r-values of UF340 in all directions were achieved by the development of the remarkable γ-fiber texture. In addition, the value of the annealed UF340 was as high as 1.96, and the Δr value was only 0.2. As a result, excellent deep drawability and relatively high strength of UF340 were realized simultaneously, making it one of the ideal materials for automobile outer panels.

Hot-Pressing Deformation Yields Fine-Grained, Highly Dense and (002) Textured Ru Targets.

Ruthenium (Ru) is a refractory metal that has applications in the semiconductor industry as a sputtering target material. However, conventional powder metallurgy methods cannot produce dense and fine-grained Ru targets with preferred orientation. Here, we present a novel method of hot-pressing deformation to fabricate Ru targets with high relative density (98.8%), small grain size (~4.4 μm) and strong (002) texture. We demonstrate that applying pressures of 30-40 MPa at 1400 °C transforms cylindrical Ru samples into disk-shaped targets with nearly full densification in the central region. We also show that the hardness and the (002)/(101) peak intensity ratio of the targets increase with the pressure, indicating enhanced mechanical and crystallographic properties. Our study reveals the mechanisms of densification and texture formation of Ru targets by hot-pressing deformation.

Texture evolution of obliquely deposited Au thin films

Understanding the formation and evolution of the texture of obliquely deposited films is of great significance for improving their performance. Among these films, Au films have many advantages and wide application prospects. However, a systematic study of texture evolution of Au films has not been reported. In this study, Au films were prepared by magnetron sputtering oblique deposition. The pole figures of films deposited with various oblique angles (γ) and thicknesses were measured by X-ray diffraction. The morphology and size of the grains on the surface and in the cross-section of the films were observed by scanning electron microscopy. The surface topography of the films was determined by atomic force microscopy. During the growth process of the films, the increase rate of roughness was faster than the transverse broadening rate of grains. The samples deposited at γ ≤ 60° were composed of densely arranged grains with inclined (111) plane fiber texture whose tilt angle increased with the increase of γ and thickness. In the films deposited at γ ≥ 70°, the grain structure evolved into highly porous nanorods, and the (111) plane texture was more slanted and dispersed. The mechanism of film texture formation during oblique deposition is discussed.

Sputtering by inverted magnetrons: influence on the texture and residual stresses in four layer Ta/W/Ta/W coatings

The aim of the study is to examine the possibilities of sputtering of multilayer coatings at a high rate of deposition on products of complex shape using inverted magnetrons. The formation of texture and residual stresses in magnetron four-layer Ta/W/Ta/W coatings deposited at voltages from 0 to –200 V on cylindrical and flat copper substrates imitating elements of the surface of complex shape products was evaluated using the X-ray method of inverse pole figures and the sin2Ψ method. The patterns of texture formation in coatings depend mainly on the bias voltage on the substrate (Us), while at Us = –200 V they differ for W and Ta layers. At Us = –100 V, the epitaxial mechanism of texture formation is realized. In the case of a cylindrical substrate, this leads to intense texture (111) of all four layers. In the case of a flat substrate, this can lead to the formation of a single-crystal texture (111) in all layers with a texture maximum width of 12°–14°. The presence of a single-crystal (111) tantalum texture corresponds to the maximum Young moduli and, accordingly, the interatomic bonding forces normal to the coating plane. This suggests that multilayer coatings with an external Ta layer have high tribological characteristics. Increasing the voltage on a flat substrate from 0 to –200 V leads to an increase in residual compressive stresses from 0.5 to 2.7 GPa for the four-layer coating under study.

Evolution of recrystallization texture in nickel-iron alloys: experiments and simulations

ABSTRACT The present work is aimed at examining the effect of solid solution on the development of recrystallization microstructure and texture in FCC materials where SFE remains unchanged on alloying addition. To elucidate the mechanisms of texture formation during recrystallization, pure Ni and Ni-Fe (20 and 40 wt.% Fe) alloys were investigated. After recrystallization, pure Ni showed a cube and a non-uniform α-fibre texture, whereas the Ni-Fe alloys showed a texture characterised by the rotated cube component, brass recrystallization (BR) orientation, and a non-uniform α-fibre. Addition of Fe to pure Ni has led to some fine differences in the recrystallization texture that have been attributed to the role of highly heterogeneous deformed microstructure in the Ni-Fe system because of alloying. However, in all the cases Cu-oriented grains are prone to early recrystallization due to relatively more heterogeneously deformed regions, whereas deformed grains having orientation <110> || ND have shown slow recrystallization. In all cases, the entire stage of recrystallization is dominated by the formation of annealing twin (Σ3) boundary. The mobility of these twin boundaries plays an important role in the evolution of the recrystallization texture, which in turn, depends on its coherency, i.e. grain boundary plane (K1) of twin boundaries. The mechanism of evolution of recrystallization texture and the role of different deformation features during recrystallization is investigated. The cellular automata simulation technique was used to simulate the recrystallization behaviour of the alloys. The simulation results were used to discuss experimental observations.

The development of a W-shaped channel extrusion for fabricating magnesium alloy shells by combining high amplitude shear strain with a shorter process

This paper introduced a novel single-pass severe plastic deformation method, W-shaped channel extrusion (WCE), for the direct manufacturing of magnesium alloy shells. Based on a strategically installed mandrel and die with a sloping asymmetric step structure, the WCE constructed a narrow severe plastic deformation gap specially reinforced by a backpressure-shear structure and an asymmetric shear-extrusion section. Therefore, slender bar with large height-to-diameter ratio (i.e. small diameter, large height) could easily be extruded into larger diameter shell in narrow gap through only one pass, and an impressive average plastic strain of over 4.1 was concurrently achieved, evidenced by upper bound theory calculation. The WCE process was further experimentally conducted on AZ80 alloy at 340 °C, demonstrating remarkable improvements in yield strength, ultimate tensile strength, and elongation of the extruded part by factors of 2.4, 2.2, and 4.3 over the as-cast condition. The consecutive multi-stage shear and high hydrostatic pressure catalyzed extreme grain refinement, favored high matrix dislocations and concurrently facilitated the early dynamic conception of granular β-Mg17Al12 particles in subgrains stage, all of which served the superior performance. Moreover, no prominent anisotropy detected in the extruded part due to the development of a special bimodal basal texture under shear stress, where its synergistic effect with grain refinement evidently promoted the balance of strength and plasticity. Finally, the mechanism of bimodal texture formation associated with specific slip activations during WCE and anisotropic weakening was revealed in detail.

Formation mechanism of texture in ultra-thin Fe Si alloy sheet with excellent medium frequency magnetic properties fabricated by multi-stage decarburizing and cold rolling

Formation mechanism of texture in ultra-thin Fe Si alloy sheet with excellent medium frequency magnetic properties fabricated by multi-stage decarburizing and cold rolling

Effect of Al Concentration on Basal Texture Formation Behavior of AZ-Series Magnesium Alloys during High-Temperature Deformation

Magnesium and its alloys have been restricted in their industrial applications due to problems related to their formability. To overcome this issue, controlling the crystallographic texture is important, and the texture formation mechanism should be investigated in relation to factors including deformation conditions and solute atoms. In particular, the effects of solute atoms on the texture formation behavior should be further analyzed because they can considerably affect the deformation behavior. Thus, in this study, to clarify the effect of aluminum concentration on the texture formation behavior and microstructure, high-temperature uniaxial compression tests were conducted on three types of AZ-series magnesium alloys (AZ31, AZ61, and AZ91). Compression was conducted at 673 K and 723 K, with strain rates of 0.05 s-1 and 0.005 s-1, up to a true strain of -1.0. Cylindrical specimens were prepared from a rolled plate that had a (0001) basal texture and was compressed parallel to the c-axis of the grains. Consequently, work softening and fiber texture formation were observed in all the specimens. During the deformation, the development of grain boundaries, which is a typical characteristic of continuous dynamic recrystallization (CDRX), was observed, and the (0001) texture was highly developed with increasing Al content. Although each alloy was associated with the same deformation conditions and mechanisms, the AZ31 alloy exhibited a non-basal texture component. The stacking fault energy contributed to the generation of slip systems and gliding, and it was seen as the main reason for texture variation.

Microstructure evolution of hot-deformed SmCo-based nanocomposites induced by thermo-mechanical processing

• The two-stage phase transition occurred successively, accompanied by grain growth. • Texture formed in 1:5H phase, not in 2:17R phase in SmCo-based nanocomposites. • Proposed a new strategy for forming c-axis textures in nanocomposites. Nanocomposite permanent magnets have ultra-high theoretical magnetic energy products, due to coupling of the soft/hard magnetic phases, inciting strict microstructural requirements. In this study, the microstructure evolution, including the phase transition, morphological changes, and texture formation, of hot-deformed SmCo-based nanocomposites under thermal–stress–strain coupling was characterized to determine a possible strategy for achieving high performance. The SmCo 5 /α-Fe nanocomposites precursor contained fine and dispersed Sm(Fe, Co) 5 and Fe-Co grains and exhibited a two-stage phase transformation accompanied by grain growth. In the early stage of deformation at relatively low temperature, the adjacent Sm(Co, Fe) 5 and Fe-Co phase formed the Sm 2 (Co, Fe) 17 -H phase, which was stable only with small grain sizes. In the high-temperature deformation stage, the Sm 2 (Co, Fe) 17 -H phase transformed into the Sm 2 (Co, Fe) 17 -R phase with large grain sizes. In addition, the strong c -axis texture formed in the Sm(Co, Fe) 5 phase but not in the Sm 2 (Co, Fe) 17 -R phase. Subsequently, the phase transition process and texture formation mechanism were systematically analyzed by transmission electron microscopy. The initiation of a slip system and/or preferential grain growth explained the formation of texture under the action of uniform stress and strain and assisted by dispersed Sm-rich nanograins. The Sm 2 (Co, Fe) 17 -R grains with poor orientations and large grain sizes did not achieve magnetic hardening, which also damage the magnetic properties. According to the results of this work, we also presented a new strategy to prepare high-performance SmCo-based nanocomposites magnets.

Deformation and texture formation mechanism of hot-deformed SmCo5 nanocrystalline magnets

Realizing the deformation and texture formation mechanism of the HD SmCo5 magnets were rarely reported, which restricted the further enhancement of its magnetic properties. Here, we prepared the anisotropic SmCo5 nanocrystalline magnets by hot pressing and hot deformation (HP-HD). The magnetic properties, texture, and microstructure of the magnets with different height reductions were systematically studied. Based on the characterization results, for the HD SmCo5 nanocrystalline magnets, it is inferred that the deformation and texture formation mechanism are attributed to the coordination of precipitated phases, dislocation slip, stacking fault formation, and regular grain rearrangement.

Abnormal texture formation and mechanical anisotropy of pre-aging extruded Mg-Gd-Y-Zn-Zr alloy with large-scale

In order to further explore the effect of pre-aging treatment on large-scale alloys, a pre-aging extruded Mg-9.32Gd-4.02Y-2.16Zn-0.48Zr (wt.%) alloy with large extrusion ratio (ER = 19.5) and extrusion temperature of 450 °C in large-scale (Φ308 mm × 800 mm) was investigated in this paper. It exhibited good properties and a more pronounced anisotropy. The comprehensive performance in the 45° direction was the best. The extrusion direction (ED) presented a high strength, while the transverse direction (TD) showed poor strength and ductility contemporaneously. The main results of strength anisotropy were the alignment orientation of the long-period stacking ordered (LPSO), fine grain strengthening, and texture strengthening. The c-axis of most of the grains in TD samples was perpendicular to the direction of applied stress because of the abnormal <0001>//ED texture, which reduced the ductility. In addition, the formation mechanism of abnormal texture has also been studied. The higher extrusion temperature reduced the critical shear stress (CRSS) of the non-basal slip system, and the higher strain promoted the rotation of the base plane along the principal stress axis under the operation of continuous non-basal slip, resulting in the abnormal <0001>//ED texture due to lattice rotation. On the other hand, dynamic recrystallization (DRX) also greatly affected the generation of the abnormal texture. Firstly, DRX produced a proportion of grains with a nucleation orientation of <0001>, then the subsequent preferential growth of DRX grains led to the vast majority of grains with an orientation tending towards <0001>. However, the former has less effect on abnormal texture than the latter.

Microstructure and texture formation mechanism of nanocrystalline anisotropic Nd-Fe-B magnets by novel hot forward-extrusion

In this paper, the microstructure and texture formation mechanism of nanocrystalline anisotropic Nd-Fe-B magnets prepared by a one-step heating forward-extrusion method were systematically studied. The hot-extruded (HE) Nd-Fe-B magnet showed the same heterogeneous microstructure characteristics as the traditional die-upsetting magnet. With the decrease of extrusion width (w1), the c-axis texture gradually enhanced, accompanied by an increasing proportion of fine-grain region and the improvement of the ordered arrangement of platelet grains. In addition, strong c-axis texture was formed by the ordered arrangement of platelet grains benefiting from the difference of stress distribution caused by the difference of side length of the extrusion port. By adjusting the dimension of the rectangle extrusion port, the magnetic properties of HE Nd-Fe-B magnets were optimized. The optimized magnetic properties with (BH)max of 241.3 kJ/m3, Hci of 1025.3 kA/m, Mr of 0.94 MA/m can be acquired for the hot extrution (HE) Nd-Fe-B magnet with extrusion width (w1) of 2.5 mm. In this method, the demoulding process can be avoided successfully by using cold pressing instead of hot pressing, which is of great significance for continuous and high-volume production.

Differential pulp cell wall structures lead to diverse fruit textures in apple (Malus domestica).

In this study, we aimed to elucidate the effect of pulp cell wall structure on fruit hardness and crispness in apples. To this end, we studied the cell wall polysaccharides in two apple varieties, "Hanfu" and "Honeycrisp," during fruit development. Compared with Hanfu, the crispness of Honeycrisp was higher, whereas its harness was lower. The intensity and distribution of immunofluorescence signals indicated that galactose and arabinose contributed to the higher hardness of Hanfu, whereas arabinose, egg-box structure, and fucosylated xyloglucans, distributed in the corners of tricellular junctions, enhanced the cell-cell adhesion and improved the crispness of Honeycrisp. Besides, fucosylated xyloglucan played an important role in promoting the formation and maintaining the strength of the cell wall skeleton and, consequently, retaining the fruit crispness. The esterification state of pectin had little effect on the fruit hardness and crispness in both varieties. Collectively, our findings provided information on the underlying mechanism of fruit texture formation in apples.

Texture Evolution during Recrystallization and Grain Growth in Non-Oriented Electrical Steel Produced by Compact Strip Production Process.

Evolution of texture and α*-fiber texture formation mechanism of Fe-0.65%Si non-oriented electrical steel produced by Compact Strip Production (CSP) process during all the thermo-mechanical processing steps were investigated using electron backscatter diffraction (EBSD) and X-ray diffraction (XRD) techniques. Columnar crystal structure of cast slab is fine and well-developed. Textures of the hot-rolled band are quite different in the thickness direction. During annealing of cold-rolled sheet, γ-fiber texture grains would nucleate and grow preferentially, and α*-fiber texture grains mainly nucleate and grow in the shear zone of α-fiber texture of cold-rolled sheet. During the recrystallization process, γ-fiber texture gradually concentrated to {111}<112>, and γ and α*-fiber texture increased significantly. {111}<112> texture priority nucleation at the initial stage of recrystallization. Due to the advantages of nucleation position and quantity, the content of α*-fiber texture is greater than {111}<112> texture in the mid-recrystallization. During grain growth process, {111}<112> oriented grains would grow selectively by virtue of higher mobility, sizes and quantity advantages than that of {411}<148 > and {100}<120>, resulting in the gradual increase of γ-fiber texture and the decline of α *-fiber texture.

Single crystalline-like crystallographic texture formation of pure tungsten through laser powder bed fusion

We successfully formed the first prominent crystallographic texture of tungsten using laser powder bed fusion (LPBF). It is difficult even to manufacture highly dense tungsten products using LPBF because of its extremely high melting point and high thermal conductivity. By tuning the laser process parameters, we succeeded in fabricating almost fully dense pure tungsten parts with a relative density of 99.1%, which is the highest value yet to be reported. More importantly, a single crystalline-like prominent crystallographic texture evolved, in which <011> preferentially oriented in the scanning direction. This texture was formed to reduce the crystal misorientation at the melt pool center, at which the solidification fronts from the right and left halves of the melt pool encounter. This texture formation mechanism is similar to that of conventional alloys with ordinary thermal properties; however, the crystal growth directionality that governs the crystallographic orientation differs according to the melt pool morphology.

Mechanism of texture formation in submicron Cu thin films

We successfully fabricated the submicron Cu thin films with different texture components and thicknesses by magnetron sputtering method, and investigated the underlying mechanism of texture formation. The X-ray diffraction, electron backscatter diffraction and transmission electron microscopy were employed to elucidate the {111}, {011}, {001} and random texture components formation mechanism. In addition, the orientation factors were calculated to clarify the influencing mechanism of grain preferential growth in the yielding submicron Cu thin films. The film sputtered at 100 W has a preponderance growth of {111} oriented grains, which is explained by the minimum of surface energy theory. With sputtering power increased to 200 W, the formation of random texture could be attributed to the presence of extensive twinning. Increase the sputtering power to 300 W and simultaneously keep the thickness to 200 nm, then the texture transforms to {001} texture component. Further increased the thickness to 1000 nm, the fraction of {011} texture component reveals preponderantly, which is controlled by the differences of orientation factors during yield process. The qualitative coincidence between the experimental results and theoretical analysis indicated that the underlying mechanism of preferential growth in the submicron Cu thin films was related to the competition of different driving forces. From adjusting the major driving force, different texture components could successfully be manipulated in submicron Cu thin films.

Evolution of microstructure, texture and residual stress of AZ31 Mg alloy in hot extrusion process

In this work, we have investigated the microstructure, texture, and residual stress of AZ31 Mg alloy at several higher extrusion temperatures (360 °C, 380 °C, 400 °C) and speeds (1 m min−1, 2 m min−1, 3 m min−1). Results show that the bimodal microstructure can be observed in all extruded Mg alloys, consisting of the fine grains in dynamic recrystallization (DRX) zone and the coarse grains in non-dynamic recrystallization (non-DRX) zone. The non-monotonic relation between average grain diameter and extrusion speed has been found. It is attributed to the promoted nucleation and inhibited grain growth at higher extrusion speed. The bimodal microstructure can maintain the stability of sharp {0002} basal texture. Schmid Factor (SF) is calculated to explain the mechanism of basal texture formation. By employing XRD with cosα method, the residual stress has been measured. The major origin of residual stress release at higher extrusion temperature is the grain growth, rather than the strengthening of basal texture. The anisotropy of residual stress distribution is related to the coupling effect of grain growth and evolution of basal texture of extruded Mg alloys.