In-plane Texture Research Articles

Stretchability of Commercial Purity Titanium Sheet

The article presents the results of tests to assess stretchability of commercial purity titanium sheet. The plastic strain ratio (r value) indicates strong normal anisotropy and weak planar anisotropy in the plastic properties. The forming limit diagram (FLD), determined by hemispherical punch stretching, exhibits limiting strains that are large at the smallest strain ratios, low at plane strain, and minimum at a strain ratio close to equibiaxial stretching. Hill’s criterion for localized necking, in conjunction with a best fit constitutive equation from the tensile test and the quadratic Hill’s yield surface, predicts the negative minor strain region of the FLD well. However, fracture as the mechanism limiting the deformation cannot be ruled out, especially as the negative minor strain region extends to the positive side with a minimum in the positive side. The increase in limit strains in the positive minor strain region beyond the minimum and the plane strain condition occurring in full dome stretching are explained as “anomalies” due to planar anisotropy. Electron backscatter diffraction (EBSD) studies show a strong basal texture that intensifies when deformed under plane strain and equibiaxial conditions. Under uniaxial tension, the basal plane texture changed to \( \left\{ {0001} \right\}\left\langle {11\bar{2}0} \right\rangle \) texture. Twinning is also found to be more under uniaxial tension. Trends in the mechanical properties correlate well with the EBSD results.

Recognition of Dorsal Hand Vein Based Bit Planes and Block Mutual Information.

The dorsal hand vein images captured by cross-device may have great differences in brightness, displacement, rotation angle and size. These deviations must influence greatly the results of dorsal hand vein recognition. To solve these problems, the method of dorsal hand vein recognition was put forward based on bit plane and block mutual information in this paper. Firstly, the input gray image of dorsal hand vein was converted to eight-bit planes to overcome the interference of brightness inside the higher bit planes and the interference of noise inside the lower bit planes. Secondly, the texture of each bit plane of dorsal hand vein was described by a block method and the mutual information between blocks was calculated as texture features by three kinds of modes to solve the problem of rotation and size. Finally, the experiments cross-device were carried out. One device was used to be registered, the other was used to recognize. Compared with the SIFT (Scale-invariant feature transform, SIFT) algorithm, the new algorithm can increase the recognition rate of dorsal hand vein from 86.60% to 93.33%.

The effect of Y content on microstructure and tensile properties of the as-extruded Mg–1Al–xY alloy

The Mg–1Al–xY (x = 3, 5, 8) alloys were prepared by melting technology and extruded at 400 °C. Microstructures of the alloys were investigated by X-ray diffraction (XRD), optical microscope (OM), and scanning electron microscope (SEM). Tensile properties of the alloys were measured. The results showed that the as-extruded Mg–1Al–xY (x = 3, 5, 8) alloys were composed of α-Mg phase and Al2Y phase and the microstructures were main dynamic recrystallization. The eutectic Al2Y phase was broken down to finer particles and dispersed more uniformly after the extrusion. The extruded alloys have (0002) basal plane texture. The tensile strength, yield strength and elongation of Mg–1Al–8Y alloy were 288 MPa, 174 MPa and 20% at room temperature, respectively. Therefore, the alloys have good mechanical properties and the fracture morphology with ductile features.

Development of REBCO Tapes on Nonmetallic Flexible Substrates for RF Applications

REBa 2 Cu 3 O 7-x (RE = rare earth) films on a flexible, low-cost, and low thermal expansion substrate offer a unique advantage for RF applications such as surface receiver coils for a magnetic resonance imaging (MRI). In this work, polycrystalline, inexpensive, lightweight, and flexible yttria-stabilized zirconia (YSZ) with low thermal conductivity and low RF loss was used as a substrate for epitaxial REBCO films. The YSZ substrate surface was planarized to a surface roughness R q of about 1 nm. Ion-beam assisted deposition was used to obtain highly oriented single-crystalline-like buffer templates. Homo-epitaxial MgO and epitaxial LaMnO 3 (LMO) thin films were deposited via reel-to-reel magnetron sputtering. The out-of-plane and in-plane texture values of LMO were optimized to 2.6° and 6.8°FWHM, respectively. Epitaxial GdYBCO was grown by an advanced metal organic chemical vapor deposition on the buffered YSZ substrates with an average in-plane texture 4.3°FWHM. A magnetization critical current density (J c ) at 77 K, 0 T measured by a physical property measurement system is 0.84 MA/cm 2 . A quality factor measured at 77 K, 12.9 GHz is comparable to that of high-quality epitaxial REBCO films single-crystal rigid substrates. The epitaxial REBCO films on the YSZ polycrystalline substrates after further optimization can be used to construct RF coils for the MRI and other RF, microwave applications.

Advance in Long-Length REBCO Coated Conductors Prepared by Reel-to-Reel Metalorganic Solution and Ion-Beam-Assisted Deposition

In the present work, we report our recent efforts to improve the homogeneity of MgO buffer layers and superconducting YBa 2 Cu 3 O 7-δ coated tapes prepared by ion-beam-assisted deposition and metalorganic solution deposition (MOD), respectively. Based on previous research results involving fluorine, a reduced atmospheric pressure is used for the MOD technique to improve the in-plane texture and suppress microcracks in the film, and then more than 500 m of MOD-coated superconducting tape is manufactured, exhibiting an excellent biaxial texture and superconducting performance. The full width at half maximum values for both in-plane and out-of-plane textured films are as low as 3° based on X-ray diffraction (XRD) measurements. The superconducting current-carrying capacities for 12-mm tapes are approximately 450-520 and 450-500 A for the 100-m level and 500-m level (77 K, self-field), respectively. The current-carrying capacities were measured by both reel-to-reel transport and an inductive system, and the results demonstrated that the cost-effective MOD technique is very promising for long-length high-quality coated conductors.

Effect of cold rolling reduction on microstructure, mechanical properties, and texture of deep drawing dual-phase (DP) steel

In this study, the microstructure, mechanical properties, and texture of deep drawing dual-phase (DP) steel subjected to different cold rolling reductions were characterized via optical microscopy (OM), scanning electron microscopy (SEM), and x-ray diffraction (XRD) techniques. The results revealed that the microstructure of the steel is composed of ferrite and a small amount of martensite after cold rolling annealing. The ferrite grain size varied only slightly with the reduction. In addition, the orientation density along the γ orientation line increased continuously with increasing cold rolling reduction ratio. Similarly, the {112}〈110〉 and {223}〈110〉 components along the α orientation line and the adjacent {554}〈225〉 and {332}〈113〉 components were strongly developed. The ratio of the {111} plane texture volume fraction to that of the {100} plane texture, i.e., V{111}/V{100}, increased initially and then decreased, reaching the optimum value at 75% reduction. The maximum strength of the steel (i.e., 430 MPa) was realized at 55% reduction. However, the best elongation and r values (29.8% and 1.46, respectively) were obtained at 75% reduction.

Significant texture improvement in single-crystalline-like materials on low-cost flexible metal foils through growth of silver thin films

Low texture spreads of single-crystalline-like materials are critical for high performance of low-cost flexible semiconductors and second-generation high-temperature superconductors based on metal foils. For texture improvement, a single-crystalline-like Ag film is epitaxially grown on an ion-beam-assisted deposition TiN substrate using magnetron sputtering. Ultra-low texture spreads are found in the thin Ag film (∼330 nm), with an out-of-plane texture spread (Δω) of ∼1.03° and an in-plane texture spread (Δϕ) of ∼1.34°. Compared with the texture spreads of the TiN substrate, Δω and Δϕ of the Ag film are reduced by ∼42 and ∼79%, respectively. Applying this Ag buffer, the texture spreads of a single-crystalline-like Ge film are reduced by ∼37% (Δω) and ∼36% (Δϕ). Factors contributing to the texture improvement by Ag are studied using single-crystalline-like Ag films with various thicknesses.

Characterization of anisotropic behaviour of ZK60 extrusion under stress-control condition and notes on fatigue modeling

The anisotropic fatigue behavior of ZK60 is investigated through stress-control tests along two different material directions: extrusion (ED) and radial (RD) directions. The in-plane random texture along RD promotes activation of twinning/detwinning deformations in both tension and compression reversals, which brings about a sigmoidal but near-symmetric shape for hysteresis loops. The stress-strain response along ED is asymmetric, which is attributed to different deformation mechanisms in tension and compression reversals. The higher fatigue strength along ED is related to lower plastic strain energy in this direction. An energy damage parameter showed a good correlation with tests performed in RD and ED.

Investigation of the Texture and Dislocation Behavior of AZ31 Magnesium Alloy Under Different Strain Rate Conditions

This study is concerned with the influence of strain rate on the plastic deformation behavior and microstructure variables of AZ31 magnesium alloy sheet. The tensile properties were measured at room temperature at a strain rate of 0.001 and 100 s-1 using a universal tensile testing machine and servo-hydraulic high-speed tensile test machine respectively. The microstructure was observed at strains of 5, 10, 15%, produced by tensile elongation. As the strain rate increased, the flow stress and the yield strength increased. The EBSD analysis showed that a texture of the (0001) basal plane was formed parallel to the rolled plate and texture was formed at random in the (101¯0) non-basal plane. Double twinning was not observed and extension and contraction twinning were observed at all strain rate levels. The fraction of twin boundaries were increased as strain rate increased. TEM analysis determined that the dislocation density of the specimen strained by 1% at a strain rate of 100 s-1 was higher than that of a strain rate of 0.001 s-1. In addition, the <c+a>dislocation was found at all strain rate levels. These results show that the deference in elongation of the AZ31 Mg alloy is dependent on strain rate. Key words: AZ31 magnesium alloy, high-speed tensile test, EBSD analysis, texture, TEM analysis, pyramidal slip

Magnetic and tunable dielectric properties of DyCrO3 thin films

DyCrO3 (DCO) belongs to the family of rare-earth chromites, some members of which exhibit magnetoelectric multiferroic properties. This work characterizes the dielectric tunability in DCO, which is typically, for conventional ferroelectrics, found to maximize near the ferroelectric to paraelectric transition. Two films of DCO were fabricated via a hybrid solution synthesis route on different substrates: one on single crystalline (001) LaAlO3 (LAO) and the other on (001) LAO coated with a conducting LaNiO3 (LNO) layer. The synthesis method resulted in films with both out-of-plane and in-plane texture in the DCO. The lattice mismatch strain between film and substrate caused a slight increase in the Neel temperature of the DCO film on LAO. Transmission electron microscopy images of the DCO film on the LNO/LAO revealed the epitaxial relationship between these phases. The temperature dependence of the relative permittivity showed diffused transition and a frequency dispersion similar to what is observed in typical relaxor ferroelectrics. Isothermal dielectric constant versus dc electric field measurements showed an electric field tunable relative permittivity (i.e., tunability). This tunability reached a broad plateau near the Neel temperature. Such maxima in dielectric tunability are typically observed near a ferroelectric–paraelectric transition, and its proximity to the magnetic ordering temperature in DCO indicates magnetically driven ferroelectricity in this material.

Biaxially textured (Bi, Pb)2Sr2Ca2Cu3Ox thin films on LaAlO3 substrates fabricated via the chemical solution deposition method

In this study, biaxially textured (Bi, Pb)2Sr2Ca2Cu3Ox ((Bi, Pb)-2223) thin films were fabricated epitaxially on LaAlO3 (LAO) single crystal substrates via the chemical solution deposition (CSD) method. In order to prevent the evaporation of Bi and Pb, a sealed face-to-face architecture for sintering was utilized. According to the results of x-ray diffraction measurements including θ/2θ-scan, ω-scan, and ϕ-scan patterns, the optimal sintering temperature was found to be 840 °C. The volume fraction of the (Bi, Pb)-2223 phase of the optimal sample was enhanced to above 80%. Favorable out-of-plane and in-plane textures were also detected, which could be attributed to an epitaxy system of (Bi, Pb)-2223 thin film and an LAO substrate with a 45° rotated alignment. A dense microstructure and thickness of about 100 nm were found by scanning electron microscopy observations of the surface morphology and cross section. The critical temperature of the optimal sample determined with the four-probe method was 103.2 K, and its critical current density values were 0.06 MA cm−2 (77 K, self-field) and 1.91 MA cm−2 (4.2 K, self-field), which were obtained by AC susceptibility measurement and a superconducting quantum interference device, respectively. This study demonstrated the feasibility of fabricating (Bi, Pb)-2223 thin films with superconducting performance via the low-cost CSD method.

A damaging block-based model for the analysis of the cyclic behaviour of full-scale masonry structures

In this paper, a damaging block-based model is proposed for the numerical analysis of the cyclic behaviour of full-scale masonry structures. Solid 3D finite elements governed by a plastic-damage constitutive law in tension and compression are used to model the blocks, while a cohesive-frictional contact-based formulation is developed to simulate their cyclic interaction. The use of tests on small-scale specimens to calibrate the mechanical properties of the numerical model is presented and discussed. The tests belong to a comprehensive experimental campaign performed on calcium silicate brick masonry. The calibrated models are used to simulate in-plane and out-of-plane cyclic tests on masonry walls made of the same material, as well as a quasi-static cyclic pushover test on a full-scale terraced masonry house. The efficiency, the potentialities and the accuracy of the model here proposed are shown and discussed. The capability of explicitly representing structural details (e.g. running bonds) and any in-plane and through-thickness texture of masonry, which appears essential to study the response of masonry structures, is guaranteed by the block-based modelling approach. A good agreement between the numerical results and the experimental outcomes is observed. This allows to validate the model in the cyclic response as well as the strategy proposed for its mechanical characterization.

Influence of working environment and built orientation on the tensile properties of selective laser melted AlSi10Mg alloy

AlSi10Mg alloy was fabricated by Selective Laser Melting (SLM) using two different atmospheres, argon and nitrogen, both in vertical and horizontal built directions. The influence of work environment and anisotropy are studied in this work by keeping all other process parameters including shielding gas pressure constant. The meso-structural features revealed scan tracks and melt pool layers while the microstructural features have showed cellular structure with α-Al matrix and its boundary made up of the eutectic mixture of Al and Si. These cells were approximately of 500 nm size as revealed by TEM analysis. The grain morphology and texture were studied using EBSD analysis. The XRD analysis revealed similarity in the phases formed in samples built under argon and nitrogen environment. Both the horizontal as well as vertical built samples contain elongated grains with 〈100〉 direction oriented along the built direction and 〈100〉 fibre texture in the XY plane. Tensile test results showed the maximum strength of 385 ± 5 MPa was exhibited by vertically built sample under nitrogen environment while the lowest strength of 338 ± 2 MPa was exhibited by horizontally built sample under argon environment. Surface roughness and porosity measured in all the conditions exhibited minor variation in the average surface roughness and porosity area fraction values. Among the samples tested under same built orientation, the variation in strength is approximately 5% higher in nitrogen environment while among the samples tested under same working environment, the variation in strength is approximately 7.5% higher in vertically built samples. This states that the influence of working environment on strength is lesser than that of the built orientation. The materials exhibited brittle failure with inclined fracture profile, fracture morphology with pores, river patterns and inter-cellular fracture plus approximately 4.5% elongation in all the tested samples, implied isotropic elongation behaviour. The samples built under both the work environments exhibited the similarity in defect structure, microstructure and nearly isotropic behaviour in mechanical properties. It inferred that nitrogen could be preferred over argon as shielding gas in SLM for its cost effectiveness.

Study on Al/Mg/Al sheet fabricated by combination of porthole die co-extrusion and subsequent hot rolling

Al/Mg/Al sheet was fabricated by the proposed porthole die co-extrusion and subsequent hot rolling (PCE-R) method. The intermetallic compounds of β-Al3Mg2 and γ-Mg17Al12 were formed in transition layer after PCE-R process, and the thicknesses of β and γ layers became larger at higher rolling temperature or higher reduction ratio. Partial dynamic recrystallization (DRX) occurred in Al layer, and Al layer mainly consisted of shear-typed {111} fiber textures. However, if the rolling reduction is as high as 75%, Al layer exhibited quite different texture components. Mg layer consisted of fine equiaxed grains and several elongated grains, implying the occurrence of near complete DRX. With the increase of rolling temperature or reduction ratio, the number of Mg17Al12 particles in Mg layer was reduced, resulting into larger grain size. Mg layer had strong basal plane texture with c-axis parallel to transverse direction. Al/Mg/Al sheet rolled at 300 °C with 65% reduction exhibited two stress-drop fracture mechanism during tensile test, and it showed excellent tensile strength of 149 MPa, and elongation of 0.13. However, Al/Mg/Al sheet rolled with 75% reduction had inferior tensile properties due to the existence of some cracks after rolling.

Microstructure development and high tensile properties of He/H2 milled oxide dispersion strengthened copper

This study describes the effect of microstructural development on high tensile properties of a newly developed He/H2 milled oxide dispersion strengthened copper in a large centimeter sized spherical morphology. Electron back scattered diffraction showed development of a strong texture of (110) plane in micron sized (1.2 μm) grains on the surface of milled spheres. A combination of microstructural features of inhomogeneous grain size, nanoscale lenticular/rectangular deformation twins, high dislocation density and fine oxide particles distribution induced a very high ultimate tensile strength (688 MPa)-ductility (8.6% elongation).

Effect of grain refinement and crystallographic texture produced by friction stir processing on the biodegradation behavior of a Mg-Nd-Zn alloy

The application of a single pass of friction stir processing (FSP) to Mg-Nd-Zn alloy resulted in grain refinement, texture evolution and redistribution of second phases, which improved corrosion resistance. In this work, an as-rolled Mg-Nd-Zn alloy was subjected to FSP. The microstructure in the processed zone of the FS-400 rpm alloy exhibited refined grains, a more homogenous grain size distribution, less second phases, and stronger basal plane texture. The corrosion behavior assessed using immersion tests and electrochemical tests in Hank￢??s solution indicated that the FS-400 rpm alloy had a lower corrosion rate, which was attributed to the increase of basal plane intensity and grain refinement. The hardness was lowered slightly and the elongation was increased, which might be attributed to the redistribution of the crushed second phases.

Controlling Topological States in Topological/Normal Insulator Heterostructures.

We have performed a systematic investigation of the nature of the nontrivial interface states in topological/normal insulator (TI/NI) heterostructures. On the basis of first principles and a recently developed scheme to construct ab initio effective Hamiltonian matrices from density functional theory calculations, we studied systems of realistic sizes with high accuracy and control over the relevant parameters such as TI and NI band alignment, NI gap, and spin–orbit coupling strength. Our results for IV–VI compounds show the interface gap tunability by appropriately controlling the NI thickness, which can be explored for device design. Also, we verified the preservation of an in-plane spin texture in the interface-gaped topological states.

Preparation of double-sided biaxially textured magnesium oxide thin films

A high-efficiency system was designed as an improvement in conventional reel-to-reel system for ion beam-assisted deposition (IBAD) and homo-epitaxy of double-sided biaxially textured MgO thin films. This system enables Hastelloy tape to flip automatically and go through the deposition area twice in order to deposit MgO on its both sides. With this system, the output of double-sided IBAD-MgO is elevated to be 30 m·h−1. A 30-m tapes with 10-nm-thick double-sided biaxially textured MgO thin films was successfully made. X-ray diffraction (XRD) and atomic force microscope (AFM) show identical quality of MgO thin films on both sides. The yield full width at half maximum values of out-of-plane texture and in-plane texture on both sides are approximately 3.1° and 5.3°, respectively. Moreover, the influence of ion beam flux and deposition rate on the texture of thin film was investigated. A process window in which biaxial texture can be obtained is found for large-scale production.

Growth, interfacial microstructure and optical properties of NiO thin films with various types of texture

NiO thin films with random, fiber and in-plane textures have been successfully deposited at near room temperature by reactive magnetron sputtering on glass, silicon and Al2O3 (0001) substrates. Self-texture related with the deposition conditions and crystallographic characters competes with the driving force from the matched substrate. Such a competition can be used to control the texture of thin films on matched substrates, especially when the promoting orientations from self-texture and substrate are different. Enhancing this competition tends to suppress the self-texture of NiO thin films on Al2O3 (0001) substrates, whereas restricting the competition is beneficial to produce the in-plane textured NiO thin films. In addition, it is found that the optical transmittance of NiO thin films on Al2O3 (0001) substrates can also be tuned by such competition. Interfacial microstructure analyses of NiO thin films on amorphous substrates clearly evidence the existence a nanocomposite layer at the initial growth, which is composed of NiO nanocrystals surrounded by amorphous matrix. In contrast, in-plane textured NiO thin films on Al2O3 (0001) substrates exhibit sharp interface without nanocrystals or amorphous matrix. We believe these results provide a general framework of tuning the textures and properties of thin films on matched substrates.

Preparation of epitaxial CaMn7O12 film via sol-gel method and its ferromagnetic properties

CaMn7O12 precursor sol was prepared by using Ca(NO3)2·4H2O and Mn(CH3COO)4·4H2O as the raw materials, acetylacetone (AcAcH) as the chelating agent, and methyl alcohol (MeOH) as the solvent. The CaMn7O12 crystalline film was obtained via dip-coating and annealing treatment on the LaAlO3 (001) single-crystal substrate. XRD θ-2θ scan indicated that the as-prepared CaMn7O12 film had strong preferred orientation along the c-axis. In addition, the results of the ω and ϕ scans demonstrated that the film exhibited outstanding out-of-plane and in-plane texture characteristics. The SEM characterization showed that the CaMn7O12 film was dense and free of cracks. The grain size was uniform with an average size of ~180 nm. Vibrating sample magnetometer (VSM) test results indicated the CaMn7O12 film was antiferromagnetic and had a saturation magnetization of 114.2 emu/cm3 at 50 K.