Evolution Of Crystallographic Texture Research Articles

Elucidating the effect of strain path-dependent crystallographic texture evolution on the electrochemical behavior of nanostructured AA2024 aluminum alloy

This research provides insight into the effect of strain path-dependent texture evolution on the electrochemical behavior of nanostructured AA2024 aluminum alloy in a phosphate buffer solution (pH = 8.3). To achieve this, AA2024 alloy sheets were processed using two methods: accumulative roll bonding (ARB) and cross accumulative roll bonding (CARB), i.e., rotating the sheets 90° around the normal direction (ND) axis between each cycle. The ARB-processed AA2024 alloy exhibited a pancake-shaped structure and included texture components of Copper {112}<111>, Brass {011}<211>, P {110}<221>, and S {123}<634>. Meanwhile, the CARB-processed AA2024 alloy had extremely fine and equiaxed nano-grains (< 100 nm) and texture components of S {123}<634>, Brass {011}<211>, Goss {011}<100>, Rotated Cube {001}<110>, and P {110}<221> after eight cycles. Electrochemical studies demonstrated an increase in corrosion current density due to high imposed strains in the ARB route, which in effect made the conditions of passive layer formation more difficult and lowered the corrosion resistance. Additionally, achieving a more uniform distribution of extremely fine grains and {011} orientation textures such as Brass {011}<211>, Goss {011}<100>, and P {110}<221> texture components in the CARB route, provided ideal conditions for forming oxide passive films with superior protection properties compared to ARB. These unique findings can contribute to the broader application of crystallographic-orientation-dependent electrochemical behavior of alloys in the field of corrosion management.

Evolution of Crystallographic Texture and Its Impact on Magnetic Losses of Non‐oriented Electrical Steel

In this study, how crystallographic texture and changes in microstructure affect the magnetic properties of a semi‐processed non‐oriented (NO) electrical steel, which is investigated in its as‐received state and after heat treatment, is evaluated. Electron backscattered diffraction analysis shows the variation in texture with a crystallographic orientation changing from a predominance of γ and α fibers to a random one after heat treatment, with a significant increase in components with &lt;100&gt; directions in the sheet plane, which are desired for NO steels because they are parallel to the direction of easy magnetization. Heat treatment has also increased the average grain size of the samples from 18 to 128 μm. Magnetic properties are analyzed over a wide frequency range and induction, presenting different behaviors in permeability and magnetic loss for the samples before and after heat treatment. The components of total magnetic loss are also evaluated, and the hysteresis loss of heat‐treated sample decreases significantly. This demonstrates that heat treatment reduces microstructural imperfections, causing a decrease in hysteresis losses. Therefore, it is concluded that the improvement in magnetic performance observed with heat treatment has its origin in the increase in fiber components related to the &lt;100&gt; directions and a decrease in microstructural imperfections.

Effects of scan rotation angle and build orientation on mechanical anisotropy in additive manufacturing 316L stainless steel

The scan rotation angle (SRA) and build orientation (BO) in the laser powder bed fusion (LPBF) process create unique microstructural features that induce mechanical anisotropy in 316L-stainless steel (SS). To thoroughly investigate their individual and collaborative effects on anisotropy, 316L-SS samples were fabricated with SRAs between adjacent layers (abbreviated as R) of R0 (0°), R45 (45°), R67 (67°), and R90 (90°), and BOs in the XY plane ranging from XY0 to XY90 at intervals of 15°. Tensile testing results revealed that XY0–R67 samples exhibited the highest yield strength (YS), ultimate tensile strength (UTS), and ductility among all samples, while the lowest YS, UTS, and ductility were observed for XY0–R0 samples. Characterization at different length scales was performed to investigate the underlying reasons contributing to mechanical anisotropy. X-ray diffraction (XRD) results indicated that all samples possessed single-phase austenitic structures with varying dislocation densities. The dislocation density had the highest contribution to the YS of LPBF-built 316L-SS in the sequence of XY0–R67 > XY0–R90 > XY0–R45 > XY0–R0. The higher dislocation density in XY0–R67 samples stemmed from the larger residual stresses associated with the higher lattice strains due to the more complex thermal histories and higher cooling rates compared to other cases. A similar phenomenon was also observed for the XY45 BO, which exhibited higher YS due to higher dislocation densities compared to other orientations, regardless of SRAs. Additionally, SRAs significantly influenced the evolution of crystallographic texture, which also affected the YS of LPBF-built 316L-SS.

Texture and lattice strain evolution in a pearlitic steel during shear deformation: An in situ synchrotron X-ray diffraction study

In-situ synchrotron X-ray diffraction experiments were conducted on the pearlitic steel sample with a carbon content of 0.74% by weight. Specimens were subjected to uniaxial loading that induced shear deformation and two-dimensional diffraction patterns were acquired. The evolution of the lattice microstrain and the strain-resolved crystallographic texture development of both ferrite (α-BCC) and cementite (θ-orthorhombic) phases were followed. The analysis revealed that the texture changed from {110}<113>α to {113}<121>α component and then, stabilized at {013}<uvw>α orientations. The θ phase exhibited a weak texture in the {100, 010, and 001}θ family planes. Additionally, it was revealed that the nucleation of interfacial defects at the α/θ interface promotes the amorphization of cementite and the activation of slip systems in less densely packed {310}α planes. The influence of microstructural changes on mechanical properties is discussed.

Dislocation Distribution, Crystallographic Texture Evolution, and Plastic Inhomogeneity of Inconel 718 Fabricated by Laser Powder Bed Fusion

Plastic inhomogeneity, particularly localized strain, is one of the main mechanisms responsible for failures in engineering alloys. This work studies the spatial arrangement and distribution of microstructure (including dislocations and grains) and their influence in the plastic inhomogeneity of Inconel 718 fabricated by additive manufacturing (AM). The bidirectional scanning strategy with no interlayer rotation results in highly ordered alternating arrangements of coarse Goss‐like {110}&lt;001&gt; textured grains separated by fine Cube‐like {100}&lt;001&gt; textured grains. The bidirectional strategy also results in an overall high density of geometrically necessary dislocations (GNDs) that are particularly dense in the fine grains. Although the Cube‐like texture desirable for isotropy is dominant, it gradually weakens during plastic deformation and the undesirable Goss‐like component (second most dominant in the as‐built microstructure) increases. The highly clustered and bimodal distribution of fine and coarse grains, textures, and GND densities causes fast localized roughening during deformation, particularly along the line row of fine Cube‐like grains. However, the chessboard strategy results in a lower GND density and a comparatively more random distribution of crystallographic texture and GNDs, with a dominant Cube‐like component (and much lower Goss‐like texture) that remains stable throughout plastic deformation. This results in more uniform deformation, reducing plastic inhomogeneity.

Unveiling the self-annealing phenomena and its effect on microstructure and texture evolution in the room temperature rolled Cu-0.13Sn-0.04Mg alloy

ABSTRACT In this study, we investigated the microstructural evolution of a Cu-0.13Sn-0.04Mg alloy that underwent heat treatment followed by room temperature rolling (RTR). Initially heat-treated specimens were rolled at room temperature (RT) with reduction ratios (RR) of 40% and 75% to perform microstructural and crystallographic textural analyses. Electron backscattered diffraction (EBSD) and transmission electron microscopy (TEM) were utilise to examine both initial and deformed microstructures. Both exhibited heterogeneous microstructural distributions. Shear bands (SBs) existed in the initial specimen and became main sites for the nucleation of new grains during heat treatment. A denser presence of SBs was noted in the RTR specimens. Remarkably, an unusual self-annealing phenomenon was observed in these specimens, culminating in the emergence of recrystallized grains at RT. A plethora of such grains was observed in the severely deformed specimens, with numerous nucleating grains appearing proximal to the SBs or deformed grain boundaries (GBs). Time dependent microstructure evolution was observed via ex-situ EBSD technique in the compressed specimens. Formation of new grains, increase in high angle grain boundaries (HAGBs), and dislocation annihilations were observed with the progress of time. The crystallographic texture evolution in the initial specimen was predominantly influenced by the S component. At lower strains, the fractions of Copper component increased, whereas at higher strains, a greater fraction of Brass and S components were induced. Following a 40% RR, a saturation in hardness value was observed, which could be potentially attributable to an accelerated rate of RT recrystallization in the case of 75% RR.

Microstructure evolution and local mechanical properties of friction stir additively manufactured (FSAM) AA5083/AA6061/AA7075 gradient composite

The current study is focused on the successful fabrication and characterization of microstructure and properties gradient composite made of 3 mm thick sheets of AA5083-O, AA6061-T6, and AA7075-T6 alloys using friction stir additive manufacturing (FSAM) technique. Two combinations of four layered FSAM builds (6756 and 7567) were fabricated successfully without any major defects at the optimized process parameters of 850 rpm (tool rotational speed) and 55 mm/min (tool transverse speed). The material mixing, interfacial bonding features, microstructure evolution, and mechanical performance within the stir zones (SZ) were thoroughly examined using advanced characterization techniques. Electron backscatter diffraction (EBSD) analysis confirmed a gradient microstructure along the build depth in both FSAM builds, with average grain sizes decreasing from 52 μm (AA5083), 46 μm (AA6061), and 40 μm (AA7075) in base metals to ∼ 4–7 μm within the SZ. The remarkable grain refinement within the SZ was mainly attributed to the dominant presence of the continuous dynamic recrystallization (CDRX) mechanism. Texture analysis corresponding to pole figures (PFs) and orientation distribution function (ODF) plots reveals the crystallographic texture evolution along the build depth. The prevalent existence of B/ B‾ and C textures throughout all regions of the FSAM builds affirms the presence of ample shear strain during the FSAM procedure. Through thickness miniature tensile and microhardness tests depict the gradient in mechanical performance for both the FSAM builds along the build depth. Microhardness gradients in the range from ∼ 80 HV0.1 to ∼ 145 HV0.1 were observed along the build depth. The axial sample in the build direction shows appreciable strength (265 MPa and 224 MPa) and uniform elongation (28 % and 24 %) for 6756 and 7567 FSAM build, respectively. Furthermore, remarkable strain hardening behaviour corresponding to hardening capacity (Hc) and hardening exponent (n) was noticed for both the axial build samples compared to AA6061-T6 and AA7075-T6 base metals. These findings underscore the potential of FSAM in fabricating functionally gradient composite materials tailored to specific functional requirements.

Crystallographic Texture Evolution in 3D Printed Polyethylene Reactor Blends.

In this work, crystallographic texture evolution in 3D printed trimodal polyethylene (PE) blends and high-density PE (HDPE) benchmark material were investigated to quantify the resulting material anisotropy, and the results were compared to materials made from conventional injection molded (IM) samples. Trimodal PE reactor blends consisting of HDPE, ultrahigh molecular weight PE (UHMWPE), and HDPE_wax have been used for 3D printing and injection molding. Changes in the preferred orientation and distribution of crystallites, i.e., texture evolution, were quantified utilizing the wide angle X-ray diffraction through pole figures and orientation distribution functions (ODFs) for 3D printed and IM samples. Since the change in weight-average molecular weight (Mw) of the blend was expected to significantly affect the resulting crystallinity and orientation, the overall Mw of the trimodal PE blend was varied while keeping the UHMWPE component weight fraction to 10% in the blend. The resulting texture was analyzed by varying the overall Mw of the trimodal blend and the process parameters in 3D printing and compared to the texture of conventional IM samples. The printing speed and orientation (defined with respect to the axis along the length of the samples) were used as the variable process parameters for 3D printing. The degree of anisotropy increases with an increase in the nonuniform distribution of intensities in pole figures and ODFs. All the highest intensity major texture components in IM and 3D printed samples (0° printing orientation) of reactor blends are observed to have crystals oriented in [001] or [001̅]. Overall, for the same throughput, 3D printed samples in the 0° orientation showed greater texture evolution and higher anisotropy compared to IM samples. Most notably, an increase in 3D printing speed increased the crystalline distribution closer to the 0° direction, increasing the anisotropy, while deviation from this printing orientation reduced crystalline distribution closer to the 0° direction, thus increasing isotropy. This demonstrates that tailoring material properties in specific directions can be achieved more effectively with 3D printing than with the injection molding process. Change in the overall Mw of the trimodal PE blend changed the preferential orientation distribution of the crystal planes to some degree. However, the degree of anisotropy remained the same in almost all cases, indicating that the effect of molecular weight distribution is not as significant as the printing speed and printing orientation in tailoring the resulting properties. The 3D printing process parameters (speed and orientation) were shown to have more influence on the texture than the material parameters associated with the blend.

Suppressing anisotropy in additive manufacturing by shear crystallographic texture development during multi-layer friction stir deposition

The solid-state additive manufacturing (AM) approach based on a strategy of sheet lamination (SL) using friction stir deposition/friction surfacing, and was investigated for multi-layer metal deposition in the present study. This resulted in synthesis of fully dense parts with a homogeneous and thermally stable fine-grain microstructure with isotropic properties by avoiding solidification-related defects and exploiting dynamic recrystallized shear crystallographic texture component. A non-heat-treatable AA5083 aluminum-magnesium alloy exhibiting serration yielding behavior was used for friction stir additive manufacturing (FSAM) solid-state deposition using a rotational speed of 1000 rpm with two working windows for the consumable rod feed rate in the range of 35–45 mm/min and a traverse speed in the field of 300–400 mm/min. The microstructural features and mechanical properties were assessed across different sections of the solid-state deposited AA5083 alloy structure to verify a pore-free structure with homogeneous and isotropic behavior. Metallography revealed the formation of uniform and refined equiaxed grains derived from continuous dynamic recrystallization (CDRX) with an average size of ∼4 μm over the entire region of the deposited wall through outstanding layers diffused adhesion. Mechanical testing of the multi-layer structure indicates isotropic tensile properties along the building direction (BD) and transverse direction, due to the shear crystallographic texture formed by thermo-mechanical processing during additive deposition process. An excellent combination of ultimate tensile strength (of 370 MPa) and elongation to fracture at ∼33 % was achieved enhanced by serration yielding tensile flow behavior due to solute element/dislocation interactions during plastic straining.

Investigations on microstructure, crystallographic texture evolution, residual stress and mechanical properties of additive manufactured nickel-based superalloy for aerospace applications: role of industrial ageing heat treatment

Investigations on microstructure, crystallographic texture evolution, residual stress and mechanical properties of additive manufactured nickel-based superalloy for aerospace applications: role of industrial ageing heat treatment

Effect of Laser Scan Speed on Defects and Texture Development of Pure Chromium Metal Fabricated via Powder Bed Fusion-Laser Beam.

Chromium (Cr) metal has garnered significant attention in alloy systems owing to its exceptional properties, such as a high melting point, low density, and superior oxidation and corrosion resistance. However, its processing capabilities are hindered by its high ductile-brittle transition temperature (DBTT). Recently, powder bed fusion-laser beam for metals (PBF-LB/M) has emerged as a promising technique, offering the fabrication of net shapes and precise control over crystallographic texture. Nevertheless, research investigating the mechanism underlying crystallographic texture development in pure Cr via PBF-LB/M still needs to be conducted. This study explored the impact of scan speed on relative density and crystallographic texture. At the optimal scan speed, an increase in grain size attributed to epitaxial growth was observed, resulting in the formation of a <100> cubic texture. Consequently, a reduction in high-angle grain boundaries (HAGB) was achieved, suppressing defects such as cracks and enhancing relative density up to 98.1%. Furthermore, with increasing densification, Vickers hardness also exhibited a corresponding increase. These findings underscore the efficacy of PBF-LB/M for processing metals with high DBTT properties.

Crystallographic texture evolution during friction stir processing of AA7075 alloy

This study investigates the effects of heat input on the crystallographic texture evolution during friction stir processing of AA7075 alloys. Three different heat input levels were applied to develop friction stir-modified regions. Electron backscattered diffraction (EBSD) was utilized to measure the micro-texture in the as-received base metal and friction stir processed (FSPed) stir zones. In particular, inverse pole figure (IPF) maps, pole figures, and orientation distribution functions were employed to compare the micro-textures of different processed regions. The results indicate that as the heat input decreases, the average microhardness of the nugget zone declines, accompanied by an increase in the size of recrystallized grains. The base metal AA7075 exhibits a predominantly rotated cube texture ({001} <110>). After friction stir processing, the stir zone transitions to a rotated cube texture with decreased intensities and the presence of copper texture ({112} <111>). Notably, as the heat input increases, the rotated cube texture transforms into a copper texture.

Crystallographic texture evolution in hot-press sintered tungsten heavy alloy with the effect of niobium (Nb) addition

This study examines the impact of niobium on the crystallographic texture evolution and grain boundary distribution of hot press sintered tungsten heavy alloy (W-4.9Ni-2.1Cu). EBSD analysis was used to examine the evolution of crystallographic texture and grain boundary character distribution in sintered compacts. The important findings of this study depict that cubic texture component {001} <111> were evolved in niobium unalloyed compacts due to the solidification of atoms aligned in a specified preferred orientation. Besides, it reveals the weakness in the cubic texture in niobium alloyed compacts due to the recrystallization followed by sub structural recovery occurrence during sintering. In addition, an increase in CSL fraction in niobium alloyed compacts illustrates the dominance of surface diffusion during sintering caused by the grain refinement attributed from the niobium enrichment at the tungsten-binder interface. Metallographic studies showed that the niobium concentration increment in WHAs has concomitant effect with sintered compacts' properties. A W-4.9Ni-2.1Cu-1 Nb alloy achieved the highest values for micro-hardness (432 HV0.5), electrical conductivity (23.74 % of IACS), and relative density (99.90 %).

Mechanism of Crystallographic Orientation and Texture Evolution of Ti60 Alloy during Plane Strain Compression

The crystallographic orientation and texture evolution mechanism of equiaxed Ti60 alloy plates were investigated in this study through plane strain compression tests. The EBSD analysis revealed that the received plate contained two characteristic textures that were perpendicular to each other, i.e., c-axis//TD (Component 1) and c-axis//RD (Component 2), with the latter being caused by the change in direction of the TD texture that was generated during the previous unidirectional rolling process into an RD direction in the cross-rolling process. The results demonstrated that, with increasing the deformation temperature from 930 °C to 960 °C and 990 °C, the intensity of the c-axis//TD texture (Component 1) initially rose to a peak value of 5.07, which then—subsequently—decreased significantly to 2.96 at 960 °C and 3.11 at 990 °C. Conversely, the intensity of the c-axis//RD texture (Component 2) remained relatively unchanged. These texture changes were correlated with slip system activity and the spheroidization of the primary alpha phase. For the c-axis//TD texture, the initial intensity of the texture components during compression at lower temperatures could be attributed to the incomplete dynamic spheroidization process of the α phase, which leads to the reinforcement of the c-axis//TD due to prismatic slip. As the deformation temperature increased, the dynamic spheroidization process became more prominent, thereby leading to a significant reduction in the intensity of the c-axis//TD texture. In contrast, the c-axis//RD texture exhibited difficulty in activating the prismatic slip and basal slip; in addition, it also encountered resistance to dynamic spheroidization, thus resulting in negligible changes in the texture intensity.

Influence of Cobalt content on the microstructure and texture evolution of hot-press sintered Tungsten nickel copper Alloy (W-Ni-Cu)

This study examines the effect of cobalt on the crystallographic texture and grain boundary evolution of hot-press sintered tungsten heavy alloy (W-4.9Ni-2.1Cu). Traditional tungsten heavy alloy with a Ni:Cu ratio of 7:3 has cobalt added (i.e., cobalt content increased from 0 to 1 wt% with a 0.25 wt% interval). The samples were produced using the hot press sintering method with the following parameters: 50 MPa pressure, 10 °C/min heating rate, 1450 °C temperature, and a 20-min hold time. The unalloyed cobalt WHA compact has a fibre texture in the (001) plane that is aligned in the 〈111〉 orientation. In addition, the cobalt-alloyed WHAs compacts exhibit a lower proportion of grain boundaries with low angles. Enhanced solid solution formation between cobalt and WHAs during liquid phase sintering led to increased compacts densification and randomised weak fibre development in cobalt-alloyed compacts. Texture deterioration (001) <111> in cobalt-added WHAs is caused predominantly by substructural recovery during liquid phase sintering. This study indicates that the addition of cobalt to the stoichiometry of WHAs resulted in the homogenous distribution of binder matrix within the compact during sintering. As a result, the W-4.9Ni-2.1Cu-1Co alloy exhibited improved microhardness (429.5 HV0.5), electrical conductivity (23.34% of IACS), and relative density (98.10%).

Evolution of texture and intergranular stresses of αZr and minority phases in Zr-2.5Nb pressure tube through synchrotron X-ray diffraction

This study investigates the impact of different processing steps on the crystallographic texture evolution of αZr and minority phases βZr and ωZr, and intergranular stresses as a function of grain orientation in a Zr2.5Nb pressure tube. This was done by analysis of diffraction data recorded in the 1-ID line of the Advanced Photon Source for high energy X-Rays (∼80 Kev) in transmission geometry on three samples with different processing conditions: extruded, cold rolled and after autoclaving. The crystallographic texture of both αZr and βZr phases changes slightly after cold rolling, with the Burgers orientation relationship between the two phases remaining intact. The texture of βZr and ωZr shows that βZr decomposition during thermal treatment is sensitive to grain orientation. A new method was proposed to obtain the orientation dependence of the intergranular stresses from the experimental pole figures. Intergranular stresses in αZr grains were low after extrusion, but rolling significantly increased them, with values with magnitude as higher as 350 MPa and a strong dependence on grain orientation. The autoclaving treatment leads to important stress relaxation, but the dependence on grain orientation remains. The βZr phase grains exhibit significant intergranular strains in both extruded and cold-rolled conditions; the hydrostatic part was associated to the presence of Nb in solid solution, with content of ∼20 % and an orientation dependence of approximately ±1 at%. The deviatoric strain was attributed to intergranular stresses, with stresses below 80 MPa for the extruded sample and ranging from −600 to 400 MPa after cold rolling.

Evolution of Microstructure and Crystallographic Texture in Deformed and Annealed BCC Metals and Alloys: A Review

Dislocation slips, twinning, shear banding (SBs), strain localization, and martensite formation are a few deformation modes that are activated in BCC metals and alloys. Strain, strain rate, and deformation temperature are other parameters that determine the activation of deformation modes in BCC alloys. This review focuses on several BCC alloys, such as beta-titanium (β-Ti), tantalum (Ta), and ferritic stainless steels (FSSs), all of which exhibit differences in deformation behavior. These alloys often undergo thermo-mechanical processing (TMP) to enhance their mechanical properties. TMP leads to the evolution of deformation-induced products, such as SBs, strain-induced martensite (SIM), strain localizations, and mechanical/deformation twins (DTs) during plastic deformation, while also influencing crystallographic texture. The deformation modes in β-Ti depend upon the stability of the β-phase (i.e., β-stabilizers); low-stability alloys show the formation of SIM along with slips and twins, whereas in highly stable β-Ti alloys, only slip+twin modes are observed as the primary deformation mechanisms. In the case of Ta, slip activity predominantly occurs on {110} planes, but it can also occur on planes with the highest resolved shear stress. The breakdown of Schmid’s law or non-Schmid behavior for Ta and Ta-W alloys has been discussed in detail. The cold rolling (CR) of FSSs results in the formation of ridges, which is an undesirable phenomenon leading to very low formability. The microstructures of the rolled sheets consist of elongated ferrite grains with in-grain SBs, which are preferentially formed in the γ-fiber-oriented grains. The formation of finer grains after recrystallization improves both the mechanical properties and ridging resistance in FSS. Therefore, this review comprehensively reports on the impact of TMP on the microstructural and crystallographic texture evolution during the plastic deformation and annealing treatment of β-Ti, Ta alloys, and FSSs in BCC materials, using results obtained from electron microscopy and X-ray diffraction.

Dynamic Shear Texture Evolution during the Symmetric and Differential Speed Rolling of Al-Si-Mg Alloys Fabricated by Twin Roll Casting.

The effects of a reduction in area (RA) and the speed ratio between the top and bottom rolls on a shear strain and the crystallographic texture evolution of Al-Si-Mg (1.0%Si-0.6%Mg) aluminum alloys fabricated by twin roll casting (TRC) were comprehensively examined experimentally and through numerical predictions. Initial twin-roll casted strips had a texture gradient from the surface to the center. ⟨111⟩//ND textures were found in the surface layer, and weak rolling textures existed in the center of the strip. The distributions of shear and plane strain compression (PSC) textures varied with the RA and differential speed ratio. Strong shear textures including a rotated cube, {100}⟨011⟩, were obtained from both the symmetric and differential speed rolling processes. Symmetric rolling with a different reduction in area (SRDRA) produced shear textures mainly in the surface layer. Differential speed rolling (DSR) caused dynamic shear textures along the thickness direction, not limited to the surface. Based on the finite element method and crystal plasticity, the effects of different RA values, differential speed ratios, and friction coefficients on shear strain and texture evolution are discussed in detail. Loads measured from work rolls during DSR decreased with an increase in the speed ratio.

Texture evolution and strengthening mechanism of CuCrZr alloys during cold rolling

The evolution of microstructure and crystallographic texture in Cu–1Cr-0.061Zr alloy strips during multi-pass cold rolling deformation was studied. The results showed that the tensile strength of Cu–1Cr-0.061Zr alloy increased from 507 MPa to 683 MPa with increasing rolling strain, while the conductivity decreased from 84.1 to 68.1 of the International Annealed Copper Standard. When the strain is 1.86–3.85, the elongation is effectively stable at 7.5%–8.5%. The local strain and grain dislocation angle inside the alloy gradually increase with the increase in strain, and the grain orientation distribution becomes more uniform and stronger. The dislocation slip generated during the rolling process leads to the concentration of grain orientation toward the <11−1> direction, causing the Goss texture ({110}<001>) to gradually transform into a Copper texture ({112}<11−1>) with relatively stable grain orientation, which significantly improves the mechanical properties at the macro level. In addition, the heat generated during the cold rolling process causes the cancellation of heterologous dislocations on a certain slip surface, resulting in a decreased dislocation density and a slight growth of nanoprecipitates. Nanoprecipitation strengthening and grain boundary strengthening are the main strengthening mechanisms in the Cu–1Cr-0.061Zr alloy, while the strength contribution of banded Cr phase dispersion is relatively small.

Microstructure and Crystallographic Texture Evolution of β-Solidifying γ-TiAl Alloy During Single- and Multi-track Exposure via Laser Powder Bed Fusion

The microstructural evolution and crystallographic texture formation of β-solidifying Ti-44Al-6Nb-1.2Cr alloy were identified under single- and multi-track exposures via laser powder bed fusion (L-PBF) for various process parameters. Under single-track exposure, the microstructure of the melt pool was divided into the band-like α2 phase in the melt pool boundary and β phase in the melt pool center. Numerical and thermodynamic simulations revealed that the underlying mechanism of phase separation was related to the variation in the cooling rate in the melt pool, whereas microsegregation induced a shift in the solidification path. Meanwhile, the crystallographic texture of the α2 phase region was identical to that of the substrate owing to the epitaxial growth of the β phase and subsequent α phase nucleation. In contrast, the β phase exhibited a ± 45° inclined <100> alignment in the melt pool, which was tilted to align along the build direction toward the center of the melt pool corresponding to the simulated thermal gradient direction. Furthermore, the narrow hatch space condition maintained the crystallographic texture to the subsequent scan, forming a continuous band-like α2 phase with a strong selection. However, the crystallographic texture in a wide hatch space condition manifested a random distribution and constituted a fine mixture of the β and α2 phases. For the first time, these results will offer an understanding of an anisotropic microstructure control via the L-PBF process and ensure the tailoring of the mechanical properties in the β-solidifying γ-TiAl-based alloys by approaching hatch spacing control.Graphic