Bulk Texture Research Articles

Microscale and Mesoscale Crystallographic Textures of Nanocrystalline Ni-Based Electrodeposits

The microscale and mesoscale crystallographic textures observed in nanocrystalline Ni, Ni-20 pct Fe, and Ni-50 pct Fe electrodeposits are described. The nanosized grains are arranged in coarse mesoscale colonies. In the as-deposited state, the bulk texture of the Ni-20 pct Fe alloy displays a dominant 〈001〉 fiber parallel to the macroscopic deposition direction (DD). The grains are elongated along the 〈001〉 crystal lattice direction, which is mostly parallel to the local DD, producing a well-defined 〈001〉//DD fiber microtexture on a local scale. The grain misorientation histograms show some content of low-angle boundaries, frequently associated with the presence of grain clusters, and are dominated by high-angle boundaries with a possible enhanced frequency of ∑5 and ∑7 coincident site lattice boundaries and a significant content of ∑3 twin boundaries. For all three alloys, the coarsened grains, obtained by annealing, within the mesoscale colonies show a fiber mesotexture characterized by a 〈111〉 axis approximately perpendicular to the colony hemispherical growth surface (parallel to the local DD). It is surmised that a similar “cobblestone” mesotexture with a 〈001〉 fiber axis already exists in the as-received state, as previously proposed by a number of the present authors and as supported by the results on the Ni-20 pct Fe alloy presented here.

Utilizing the meso-scale grain boundary stress to estimate the onset of delamination in 2099-T861 aluminium–lithium

Aluminium–lithium alloys provide a lower density and higher stiffness alternative to other high strength aluminium alloys. However, many Al–Li alloys exhibit a non-traditional failure mechanism called delamination, which refers to the failure of the elongated grain boundary interface. In this investigation, delaminations were observed after cyclic deformation of both uniaxial and torsion experiments. A cyclically stable rate-independent crystal plasticity framework with kinematic hardening was developed to address many experimental trends of stabilized cyclic plasticity. Utilizing this framework, meso-scale grain boundary interface stresses were estimated with uniform deformation and bi-crystal models. These models are computationally amenable to investigate both orientation dependence and the statistical nature of the grain boundary stresses for a given bulk texture and nominal loading. A coupled shear-normal Findley-based damage parameter was formulated to quantitatively characterize the nucleation of delamination consistently with experimental trends.

Changes in soil chloride following shrub removal and subsequent regrowth

Rates of groundwater recharge are especially unpredictable in semiarid regions, partly because of the role that vegetation plays in soil–plant–water dynamics. Understanding how abiotic and biotic variables affect water movement and associated soil-chloride distribution is essential to estimating groundwater recharge. Converting shrubland to grassland reduces rooting depth and plant cover, at least temporarily. In turn, reduced rooting depth increases leaching of soil chloride from the root zone when evaporative water losses are less in the grassland than in the original shrubland. This study contrasts soil and vegetation effects on soil chloride in semiarid rangelands. We established experimental plots that represent a successional chronosequence. Three native, undisturbed stands of rangeland brush (control) dominated by mature honey mesquite ( Prosopis glandulosa) were compared with adjacent land plowed of vegetation at different times (in 1991, 2001, and 2005) and were subsequently allowed to regrow (3 locations × 4 plot types). Soil samples were collected at incremental depths up to 4.2 m and analyzed for physical properties (bulk density, texture, and others), chloride concentration, and root biomass. Aboveground vegetation surveys were also conducted. We expected shallower rooting depth for at least 5 years after conversion of shrubland to grassland and attributed deeper peak soil-chloride concentration to increased deep drainage potentially leading to groundwater recharge. Differences among soil abiotic properties were too minor to change chloride distribution. Rather, differences in chloride distribution were related to changes in vegetation. Shrub cover increased over time after clearing. Grass cover peaked in the 5-year treatment plots and decreased as shrub species regained dominance. Contrary to expectations, root biomass increased for approximately 5 years following the clearing of shrubs, but then it decreased with time. Roots were shallowly distributed in earlier successional plots. Vegetation removal greatly reduced root-zone total chloride in 5- and 15-year treatment plots compared with control plots, suggesting chloride had been flushed from the profile following brush removal, after as short a time as 5 years. In addition, deepest peak soil-chloride concentration occurred in 5-year plots. We created a stepwise multiple regression model based on related soil and vegetation attributes. According to the model, time since treatment accounted for 24% of the variation in the depth to maximum chloride concentration, and root depth accounted for an additional 20% of the variation. Hydrologic changes following brush removal were evident in our study area within the first 5 years, and they are likely to positively influence groundwater recharge.

Intergranular Strain Evolution in a Zircaloy-4 Alloy with Basketweave Morphology

A Zircaloy-4 alloy with Widmanstatten-Basketweave microstructure has been used to study the deformation behavior at the grain level. The evolution of internal strain and bulk texture is investigated using neutron diffraction and conventional microscopic techniques. The macroscopic behavior and intergranular strain development, parallel and perpendicular to the loading direction, were measured in situ during uniaxial tensile loading. It was observed that twinning plays a major role in both microstructural changes and polycrystalline plasticity.

Nucleation and Growth of Surface Texture during α-γ-α Transformation in Ultra Low Carbon Steel Alloyed with Mn, Al and Si

. It is well known that surface energy anisotropy is one of the driving forces for the orientation selection at the metal-vapour interface. This affects the microstructure and texture evolution at the surface during phase transformation, which is an inherent feature of low-alloyed low-carbon steels. This paper investigates the nucleation and growth of the surface texture by orientation contrast microscopy. It has been found that the surface texture is dominated by {001} oriented grains, which exhibit a remarkable orientation gradient from the centre of the grain towards the edge. The {001} oriented grain centre gradually rotates around a <110> axis in small incre¬mental steps when nearing the edge of the grain. Towards the edge the accumulated rotation angle has commonly reached a value of 30°. Underneath the surface grains (~30 µm) the bulk texture consists of a strong -fibre.

Influence of Cutting Speed, Feed Rate and Bulk Texture on the Surface Finish of Nitrogen Alloyed Duplex Stainless Steels during Dry Turning

This paper presents the results of experimental work carried out in dry turning of cast duplex stainless steels (ASTM A 995 Grade4A and ASTM A 995 Grade5A) using TiC and TiCN coated cemented carbide cutting tools. The turning tests were conducted at five different cutting speeds (80, 100, 120, 140 and 160 m/min) and three different feed rates (0.04, 0.08 and 0.12 mm/rev) with a constant depth of cut (0.5 mm). The influence of cutting speed and feed rate on the machined surface roughness was investigated. Texture analysis (Bulk) was also carried out to study the impact of preferred orientation on the resulting surface roughness. The result reveals that the increasing cutting speed decreases the surface roughness till a particular point and then increases whereas; the surface roughness value decreases with the decreasing feed rate. Presence of alpha fiber (Bulk texture analysis) in the austenite phase of 4A work piece material leads to better surface finish. Among both the grades, surface finish of grade 4A is better than grade 5A work piece material.

Novel Nanostructures from Self‐Assembly of Chiral Block Copolymers

A diblock copolymer system constituting both achiral and chiral blocks, polystyrene-block-poly(L-lactide) (PS-PLLA), was designed for the examination of chiral effects on the self-assembly of block copolymers (BCPs). A unique phase with three-dimensional hexagonally packed PLLA helices in PS matrix, a helical phase (H*), can be obtained from the self-assembly of PS-rich PS-PLLA with volume fraction of PLLA f PLLAv = 0.34, whereas no such phase was found in racemic polystyrene-block-poly(D.L-lactide) (PS-PLA) BCPs. Moreover, various interesting crystalline PS-PLLA nanostructures can be obtained by controlling the crystallization temperature of PLLA (T(c,PLLA) ), leading to the formation of crystalline helices (PLLA crystallization directed by helical confined microdomain) and crystalline cylinders (phase transformation of helical nanostructure dictated by crystallization) when T(c,PLLA) < T(g,PS) (the glass transition temperature of PS) and T(c,PLLA) ≧ T(g,PS) , respectively. As a result, a spring-like behavior of the helical nanostructure can be driven by crystallization so as to dictate the transformation (i.e., stretching) of helices and to result in crystalline cylinders. For PS-PLLA with PLLA-rich fraction (f PLLAv = 0.65), another unique phase, a hexagonally packed core-shell cylinder phase with helical sense (CS*), in which the PS microdomains appear as shells and PLLA microdomains appear as matrix and cores, can be found in the self-assembly of PLLA-rich PS-PLLA BCPs. The formation of those novel phases: helix and core-shell cylinder is attributed to the chiral effect on the self-assembly of BCPs, so we named this PS-PLLA BCP as chiral BCP (BCP*). For potential applications of those materials, the spring-like behavior with thermal reversibility might provide a method for the design of switchable nanodevices, such as nanoscale actuators. In addition, the PLLA blocks can be hydrolyzed. After hydrolysis, helical nanoporous PS bulk and PS tubular texture can be obtained and used as templates for the formation of nanocomposites.

Recrystallization texture development in single-phase Zircaloy 2

Cast and hot forged Zircaloy 2, with Widmanstätten structure was cold rolled to 40 and 60% reductions. The bulk texture development for both reduction percentages, during subsequent recrystallization were similar and can be summarized as an increase in texturing at the initial stages (till 10–15% recrystallization) and a drop beyond 20–24% recrystallization. Microtexture measurements revealed three types of recrystallized/recovered grains: (I) Grains originating from strain localizations: These were textured and their orientations fell within an approximate band of negative textural softening; (II) Grains originating from ‘deformed bands’: These were of randomized orientations, originating from well recovered stretches—generalized as ‘deformed bands’; (III) Extended recovery: This was observed for selective grains/orientations—orientations broadly linked with positive textural softening. The first type of grains dominated the early recrystallization stages and their preferred presence (or frequency advantage) was responsible for the increased texturing. The observed randomization at the subsequent stages of recrystallization was caused by the size advantage of the recrystallized grains originating from the ‘deformed bands’.

Microstructure and mechanical property of the ECAPed Mg2Si/Mg composite

Abstract Equal channel angular pressing (ECAP) of the in situ Mg2Si reinforced Mg composite was performed with route Bc up to 8 passes using a 90° die. Refinement and re-distribution of the reinforced phase Mg2Si was investigated. Bulk texture development during ECAP was characterized by neutron radiation. Results showed that only the eutectic Mg2Si (Type-II) was proposed to be effective for preparing the in situ Mg2Si/Mg composite. Neutrons texture analysis briefly illustrated that a 〈00.2〉 basal fiber with the obtainment of less shear effect was formed. But the asymmetry of basal fiber around the ECAP direction was also observed. Both uniform texture and homogeneity distribution of Mg2Si particles played an important role in the tensile behavior of ECAPed composite.

Theory and computation of directional nematic phase ordering

A computational study of morphological instabilities of a two-dimensional nematic front under directional growth was performed using a Landau-de Gennes-type quadrupolar tensor order parameter model for the first-order isotropic-nematic transition of 5CB (pentyl-cyanobiphenyl). A previously derived energy balance, taking anisotropy into account, was utilized to account for latent heat and an imposed morphological gradient in the time-dependent model. Simulations were performed using an initially homeotropic isotropic-nematic interface. Thermal instabilities in both the linear and nonlinear regimes were observed and compared to past experimental and theoretical observations. A sharp-interface model for the study of linear morphological instabilities, taking into account additional complexity resulting from liquid-crystalline order, was derived. Results from the sharp-interface model were compared to those from full two-dimensional simulation identifying the specific limitations of simplified sharp-interface models for this liquid-crystal system. In the nonlinear regime, secondary instabilities were observed to result in the formation of defects, interfacial heterogeneities, and bulk texture dynamics.

Sources of recrystallized grains and their contributions in recrystallization of an AA3104 aluminium alloy

The hot rolled AA3104 ingot was cold rolled to 40%, 66%, 80% and 90% reductions. The cold rolled sheet was subsequently recrystallized at two different annealing temperatures of 573 K and 773 K. The bulk texture developments, both deformation and subsequently after recrystallization, were measured by X-ray ODFs (orientation distribution function), while recrystallized (and in few cases the partially recrystallized or recovered) samples were studied by SEM-EBSD (scanning electron microscope based electron backscattered diffraction).

Surface energy controlled α-γ-α transformation texture and microstructure character study in ULC steels alloyed with Mn and Al.

In this article, an ultralow-carbon steel grade alloyed with Mn and Al has been investigated during α–γ–α transformation annealing in vacuum. Typical texture and microstructure has evolved as a monolayer of grains on the outer surface of transformation-annealed sheets. This monolayer consists of <100>//ND and <110>//ND fibre, which is very different from the bulk texture components. The selective driving force is believed to reside in the anisotropy of surface energy at the metal–vapour interface. The grain morphology is very different from the bulk grains. Moreover, 30–40% of the grain boundary interfaces observed in the RD–TD surface sections are tilt incoherent <110> 70.5° boundaries, which are known to exhibit reduced interface energy. Hence, the conclusion can be drawn that the orientation selection of surface grains is strongly controlled by minimization of the interface energy; both metal/vapour and metal/metal interfaces play a roll in this.

Effect of a High Magnetic Field on Eutectoid Point Shift and Texture Evolution in 0.81C-Fe Steel

A 12 T magnetic field has been applied to the annealing process of a 0.81%C-Fe (wt.%). It is found that the magnetic field shifts the eutectoid carbon content from 0.77 wt.% to 0.83 wt.%. The statistical thermodynamic calculations were performed to calculate the eutectoid temperature change by the magnetic field. Calculation shows that the increase of the eutectoid temperature by a 12 T field is 29∘C. Synchrotron radiation measurements were performed to measure the pole figures of the samples and were analyzed by MAUD to determine the bulk texture of the ferrite phase In the field-treated and non field-treated samples. Results show that although there is no specific preferred orientation appearing by applying the magnetic field, slight enhancement of (001) fiber component occurs in both the sample normal direction (ND) and the transverse direction (TD). This effect might be related to the magnetic dipolar interaction between Fe atoms in the transverse field direction.

Bulk Texture Measurement of Interstitial-Free Annealed Steel Using Gaussian Integrated Intensities of Neutron Diffraction Spectra

{110}, {200} and {211} neutron diffraction profiles of an interstitial-free annealed steel sheet were measured on 5 � 5 degrees stereographic angle grids, and several evaluation methods of diffraction intensity were employed to calculate the bulk texture, including the peak intensity at a constant 2theta angle, the simply summed intensity in a constant 2theta angle spread and the Gaussian integrated intensity obtained by single peak fitting of each profile. The comparison among differently evaluated bulk textures shows that a stronger f111ghuvwi fiber component and a weaker f001gh110i rotated cube component appear in the texture of investigated steel and the Gaussian integrated intensity method with proper coefficient constraints possesses a higher sensitivity to both weak texture components and strong ones. The crystallographic orientation maps obtained from electron backscattering diffraction and the bulk textures estimated from X-ray diffraction confirm the feasibility of the neutron bulk texture based on the Gaussian integrated intensity, suggesting that it can be suitably utilized to evaluate the global orientation distribution characteristics of heterogeneous materials. [doi:10.2320/matertrans.MRA2008086]

Effect of Processing Schedule on the Microstructure and Texture of 0.78 wt% Cr Extra-low-carbon Steel

An extra-low-carbon steel was alloyed with 0.78 wt% Cr and subjected to three different processing schedules involving: (i) warm rolling to 65% reduction at 640°C, (ii) warm rolling to 80% reduction at 580°C and (iii) warm rolling to 65% reduction at 640°C followed by cold rolling to 40% reduction. Increasing the severity of the deformation resulted in an increase in the number of grains containing in-grain shear bands. X-ray bulk texture analysis indicates that the γ-fibre intensity was slightly higher in the steel warm rolled at 580°C than at 640°C and after cold rolling. Transmission electron microscopy and atom probe tomography revealed that Cr carbides were formed after all processing schedules. Carbon segregation to dislocations was also observed. Although the addition of 0.78 wt% Cr produced a volume fraction of carbides that was three orders of magnitude higher than those previously observed in 0.48 wt% Cr steels, a significant amount of solute Cr remained confined in the matrix and did not lead to any further depletion of the solute carbon.

Using fish gelatin and pectin to make a low-fat spread

This preliminary work involved the characterization of a low-fat spread made of fish gelatin and pectin with or without salt addition and pH adjustment. The samples prepared were characterized by temperature sweep, bulk density determination, texture analysis and morphology evaluation. It was found that a decrease in fish gelatin to pectin ratio resulted in an increase in bulk density, firmness, compressibility, adhesiveness, elasticity and melt ability. In addition, spreads prepared at high acidity gave rise to syneresis, which could be remedied with addition of sodium chloride.

Effect of cold rolling reduction and intercritical annealing temperature on the bulk texture of two TRIP-aided steel sheets

High strength TRIP-aided steel sheets with high formability and better ductility are of industrial interest. Texture control and retained austenite characterization are considered as the main factors with respect to the formability and ductility. Processing parameter such as initial conditions of hot rolling, cold rolling to final size of sheet, intercritical annealing after cold rolling and subsequent isothermal heat treatment to achieve TRIP specification in product, affect bulk texture of sheets. Moreover, chemical composition of steel should be noted especially because it can change the intensity of orientation and final macro texture of sheet. In this work, the effect of cold rolling and intercritical annealing on texture development has been investigated for two TRIP-aided steel sheets, which are different in C, Si and Al content. Results show that the cold rolling extends the γ-fiber on these grades of steel, whereas any intensive α-fiber components were not observed by change of cold rolling reduction. Also the effect of cold rolling on final texture of experimented materials is different and depends on chemical composition of steel. In contrary, intercritically annealing of cold rolled sheets decreases the intensity of γ-fiber so that the chemical composition of TRIP steel would influence effectively.

Reliable Titanium Aluminide Texture Measurement Using EBSD

γ-TiAl has a tetragonal structure that is almost cubic (c/a ≈ 1.02). As a result of this, the electron backscatter diffraction patterns (EBSPs) of orientations related by 90°&lt;100] rotations are almost identical. Reliable orientation measurement during automated EBSD mapping requires distinguishing very small differences in the positions of certain bands within the EBSPs. EBSD was used to measure the micro-texture and bulk texture of γ-TiAl hot-deformed under conditions approximating plane-strain compression. The reliability and accuracy of the indexing was assessed by inspecting the orientation maps for misindexing and by comparing the texture measured using EBSD with that measured using X-ray diffraction (XRD). Using Advanced Fit refinement and high-resolution EBSPs produced reliable and accurate results. Substantial misindexing was present when the EBSPs were indexed using the Hough transform method alone.

Crystallographic Texture Change of Pilgered Zirconium Alloy Tubes with Heat Treatment

Crystallographic texture of pilgered zirconium alloy tubes was analyzed by neutron diffraction, electron backscatter diffraction (EBSD) and X-ray techniques to study bulk and local texture change with pilgering and heat treatment above re-crystallization temperature. Pilgering resulted in slightly inclining (001) planes to sample normal direction, and aligning effectively (100) planes to the normal of radial direction, respectively. (001) planes of the zirconium tube uniformly exist in radial and tangential directions, however, the (001) planes moved from tangential to radial directions after pilgering followed by heat treatment for 20 hours at 540°C. Some of (001) and (100) planes of pilgered tube were paralleled to longitudinal direction by re-crystallization.

Studies on Production and Thermo-Mechanical Treatment of 0.32% Nitrogen Alloyed Duplex Stainless Steel

Duplex stainless steel with nitrogen content 0.32% was produced using a conventional induction furnace under normal ambient atmosphere. The samples were subsequently hot forged to various size reductions (23-57%). Both the as-cast and the hot-forged samples were examined for changes in the microstructure and mechanical properties. The results reveal that the optimal-mechanical properties were noticed for a forging deformation of 48%. Texture analysis was carried out in these samples using Inverse Pole Figures (IPF) and Orientation Distribution Function (ODF). However, IPF and ODF results revealed that bulk texture was weak after hot forging.