Inhomogeneous Texture Research Articles

Microstructural inhomogeneity and biaxial stretching limits in aluminium alloy AA6016

The ductility of sheet metals in the regime where both principal in-plane strains are positive is strongly dependent on macroscopic inhomogeneity of the sheet. This can be clearly seen when the grain size becomes large compared with the sheet thickness. However, even with quite small grain sizes there is a tendency in aluminium alloys for grains of similar orientation to occur in colonies, and this complicates any simple correlation between grain size and limit strains in stretching. Sheets of the alloy AA6016 Al–Mg–Si were heat treated to give a wide difference in grain size, and the microstructure characterised using electron back scattered diffraction (EBSD) electron microscopy, which can reveal the presence of orientation colonies. Marciniak driving blank tests were used to reveal the development of dimensional inhomogeneity and the limit strains in balanced biaxial tension. An approach using the Marciniak–Kuczynski model with yield functions derived from texture data and the ‘defect’ associated with the measured inhomogeneity of crystallographic texture gives first-order predictions of the limit strains in this material, although issues of texture evolution and adequate quantification of inhomogeneity need further consideration.

압연재에서 불균일 집합조직의 형성

압연재에서 불균일 집합조직의 형성

Earing Behavior and Crystallographic Texture of Aluminum Alloys during Cold Rolling

Earing behavior and crystallographic texture during cold rolling have been investigated for two commercial can body aluminum alloys. It is found that earing behavior can be inferred from texture information. The recrystallization texture causes 90° earing, while the deformation texture results in 45° earing. A strong recrystallization texture (or a high 90° earing) of a hot band causes a later appearance of lower 45° earing in the final gauge sheet and thus is desirable for industry. The earing behavior is better indicated by the delta function, which is characterized as the intensity difference between the deformation texture and the softening texture. The results indicate that the earing behavior during cold rolling can be quantitatively monitored by the crystallographic texture. In addition, effects of the texture inhomogeneity through-thickness have also been investigated and discussed.

Automaticity and attention: investigating automatic processing in texture segmentation with event-related brain potentials

The present article deals with the question of automaticity and/or plasticity of processes in early vision. The detection of irregularities in an otherwise homogeneous surrounding, as studied in texture segmentation tasks, is considered an example of an automatic process in the processing of visual information. Participants in texture segmentation experiments are usually instructed to respond to the texture stimuli, i.e. attention is completely allocated towards them. Automaticity, however, would imply that processing takes also place when no attention is allocated to the texture stimuli and participants, e.g. perform another primary task. We investigated the automaticity of texture segmentation by recording Event-related potentials which allow to investigate processing also when no overt response is given. Three experiments investigated the role of attention in texture segmentation by varying task relevance of the texture stimuli. Participants had to either discriminate homogeneous or inhomogeneous textures or had to perform a different primary task of varying complexity. Two components were found to be sensitive to texture segmentation, a posterior N2 and a positivity within the P3 time interval. Both components were also observed when texture segmentation was task-irrelevant. However, while the posterior N2 was not affected by the complexity of the primary task and thus showed some degree of automaticity, the P3 was found to be dependent on the attentional resources left over by the primary task.

Origin of Inhomogeneity in Pulsed Excimer-Laser Crystallized Silicon Films Studied by Computer Simulation

AbstractIn order to understand the occurrence and development of inhomogeneous poly-Si texture in the polycrystallization process of poly-SiTFT fabrication, we have simulated 1) the influence of pulse energy (PE) and optical axis (OA) fluctuations on the texture of poly-Si films and 2) the interference between both fluctuations, under the single-pulsed XeCl laser irradiation at the overlapping ratio 98%. The frequency of fatal irregular pulses in the PE fluctuation is much more than that in the OA fluctuation (pointing stability). Once the poly-Si texture suffers a fatal irregular pulse over the complete melting (CM) point, the inhomogeneous texture caused is never recovered by the following overlapping irradiation and no columnar structure is formed. However, when no irregular pulses exceed the CM point, the partial inhomogeneous texture caused in the poly-Si films is recovered by the thinning out of small Si grains in the texture and a columnar structure is formed. The key to the issue of fatal irregular pulses should be not only the reduction of PE and OA fluctuations but also the optimum selection of pulse energy not over the CM point.

Ultrasound features of blunt testicular injury

This is a retrospective study of ultrasound examination for patients with blunt scrotal trauma. Fifteen patients were examined over an 18-month period. The purpose of the study was to discover the ultrasonic features of blunt testicular trauma and to distinguish less severe from more severe injury with testicular rupture requiring surgery. Three had ultrasonic findings of acute testicular rupture and this was confirmed by surgery. The ultrasound features of testicular trauma with rupture are irregularity of testicular outline and inhomogeneity of testicular texture. The value of ultrasound in diagnosing patients with testicular rupture and, therefore, requiring urgent surgery is discussed. In our limited study, irregularity of testicular outline was the distinguishing feature of rupture.

Alteration of sonographic texture of the endometrium in post‐menopausal bleeding

Background. The purpose of this study was to assess the utility of transvaginal ultrasonography in the evaluation of endometrial morphology in addition to the standard criterion of endometrial thickness for selecting patients for endometrial sampling.Methods. Two hundred and seven consecutive cases of postmenopausal bleeding were evaluated by transvaginal ultrasound. Endometrial thickness was measured as the maximum anteroposterior thickness of the endometrium including both the anterior and posterior layers, in the sagittal long axis view. The morphology of the endometrium was studied and categorized as homogeneous, focally increased echogenecity, diffusely increased echogenecity or diffusely inhomogeneous. Patients were followed up for clinical course and endometrial histopathology.Results. Textural inhomogeneity was observed in all the three cases of endometrial cancers with endometrial thickness of less than 6 mm, and, in ten out of 11 cases of a more than 6 mm thick endometrium. On the other hand the endometrial texture was homogeneous in all cases of endometrial atrophy/tissue inadequate for diagnosis, with thickness of less than 6 mm.Conclusion. This study adds the dimension of abnormal echogenecity of the endometrium to the currently followed criterion of endometrial thickness with a view to enhance accuracy, both for a better prediction of atrophy and a higher prediction for endometrial cancer. Expectant management can be offered to patients with a homogeneous endometrium which is 6 mm thick or less. Aggressive evaluation for a malignancy must be made if there is a focal increased echogenecity or a diffuse increased echogenecity even in a thin endometrium.

X-ray characterisation of size, strain and texture inhomogeneities in ultra fine grained copper processed by equal channel angular extrusion

This study gives a characterisation using X-rays of variations in texture and microstructure of copper billets obtained by the ECAE (Equal Channel Angular Extrusion) process. Billets were produced using the so-called route C with an extrusion angle of 120° It is shown that a significant texture gradient is observed through the width of the ECAE processed billet. In addition, we demonstrate that the amount of micro-strain and the size of the coherently diffracting domains depend on which peak of a given family of planes is investigated as well as on the exact location in the sample.

Adenomyosis: sonographic findings and diagnostic accuracy.

The purposes of this study were to evaluate the accuracy of pelvic sonography in identification of adenomyosis and to characterize the most commonly seen sonographic features. We identified all patients over a 10 year period in whom a prospective diagnosis of adenomyosis was suspected on the basis of sonographic findings and who had undergone hysterectomy at a single hospital. Patients were referred for sonography based on standard indications. Sonographic features used in the diagnosis of adenomyosis consisted of two or more of the following: a mottled inhomogeneous myometrial texture, globular appearing uterus, small cystic spaces within the myometrium, and a "shaggy" indistinct endometrial stripe. Correlation was made with the pathology report on the hysterectomy specimen. Fifty-one women met the study criteria. Forty-three of 51 (84.3%) patients sonographically suspected of having adenomyosis were confirmed as having adenomyosis by pathologic examination. All patients with adenomyosis had a mottled heterogeneous appearing uterus, 95% had a globular uterus, 82% had small myometrial lucent areas, and 82% had an indistinct endometrial stripe. Eight patients (15.6%) who had been suspected of having adenomyosis by pelvic sonography did not have adenomyosis reported in the pathology specimen. Six of these eight (75%) patients had multiple small fibroids, one had stage IV endometriosis, and one had a normal uterine specimen with no evidence of pathology. Pelvic sonography provides an accurate diagnosis of adenomyosis in the majority of cases.

Alteration of sonographic texture of the endometrium in post-menopausal bleeding a guide to further management

The purpose of this study was to assess the utility of transvaginal ultrasonography in the evaluation of endometrial morphology in addition to the standard criterion of endometrial thickness for selecting patients for endometrial sampling. Two hundred and seven consecutive cases of postmenopausal bleeding were evaluated by transvaginal ultrasound. Endometrial thickness was measured as the maximum anteroposterior thickness of the endometrium including both the anterior and posterior layers, in the sagittal long axis view. The morphology of the endometrium was studied and categorized as homogeneous, focally increased echogenecity, diffusely increased echogenecity or diffusely inhomogeneous. Patients were followed up for clinical course and endometrial histopathology. Textural inhomogeneity was observed in all the three cases of endometrial cancers with endometrial thickness of less than 6 mm, and, in ten out of 11 cases of a more than 6 mm thick endometrium. On the other hand the endometrial texture was homogeneous in all cases of endometrial atrophy/tissue inadequate for diagnosis, with thickness of less than 6 mm. This study adds the dimension of abnormal echogenecity of the endometrium to the currently followed criterion of endometrial thickness with a view to enhance accuracy, both for a better prediction of atrophy and a higher prediction for endometrial cancer. Expectant management can be offered to patients with a homogeneous endometrium which is 6 mm thick or less. Aggressive evaluation for a malignancy must be made if there is a focal increased echogenecity or a diffuse increased echogenecity even in a thin endometrium.

The Influence of Tension on the Development of Rolling Textures

The texture inhomogeneity during rolling is one of the greatest problems. Especially, shear textures develops more easily during ferritic rolling of steel sheets at high temperatures owing to friction between rolls and the material. In this study, the influence of front and back tensions on the texture development during ferritic rolling has been studied. The rolling textures were simulated using the full constraints Taylor-Bishop-Hill model with the strain history obtained from finite element analysis. The calculated textures showed that the back tension rolling could reduce the shear component more effectively than front tension or rolling without tension. However, the experimental results showed that the tension effect was very small compared to the prediction. The results were discussed based on the effects of friction, initial sheet texture, back tension, and flow stress.

Simulation of the anisotropic growth of goss grains in Fe3%Si sheets (grade HiB)

In classical simulation of abnormal grain growth, the microstructure is generally assumed to be homogeneous in size and the texture randomly distributed on such a theoretical microstructure which characterizes the primary recrystallized state. Experimentally, this last assumption could not be verified in Fe3%Si sheets (grade HiB). Consequently, a new simulation procedure has been implemented using a real microstructure measured by Orientation Imaging Microscopy (OIM) as an input data set. In this first work, the influence of the texture inhomogeneity has been analyzed from a theoretical point of view using Orientation Distribution Function (ODF) calculations and Monte-Carlo simulations without correlation with experimental measurements. The present paper deals with firstly the evolution of both microstructural and textural inhomogeneities and secondly the comparison, grain by grain, at several time steps of the experimental and simulated results obtained during secondary recrystallization.

Influence of the Texture on Mechanical Properties of the Al-Li Alloy 1441

Results of texture investigations in sheet and plate of the Al–Li alloy 1441 are presented. The peculiarities of fracture surface morphology formation during fatigue crack propagation tests in dependence on texture inhomogeneity are considered. The deviation of the fatigue crack from the principal direction in center-notched specimens could be related to occurrence of a {110} 〈112〉 texture. The formation of crystallographic faceted fracture surfaces results from cracks extending by slip along equally shear stressed {111} 〈110〉 slip systems ahead of the crack tip.

Calculating Radial Textures in Bushes* Made of the Alloy Mn-Al-C Upon Upsetting Into a Container

The alloy Mn–Al–C (magnetic τ-phase) has a face-centered tetragonal crystal lattice with the superstructure L10 (Shangurov et al., 1990). The tetragonal crystal axes c (the directions 〈001〉 of easy magnetization) of the grain lattices of a polycrystal permanent magnet having a form of a bush must be preferably oriented along the corresponding bush radius. Such bushes with a pronounced radial texture are used, for example, as stators of micromotors. In the present paper the forming of this radial texture (001) in bushes made of the alloy Mn–Al–C is investigated theoretically. Texture inhomogeneity is taken into account by solving the boundary value problem of plasticity.

The Neurophysiology of Reminiscence

The cognitive map is often assumed to be a Euclidean map that isometrically represents the real world (i.e., the Euclidean distance between any two locations in the physical world should be preserved on the cognitive map). However, accumulating evidence suggests that environmental boundaries can distort the mental representations of physical space. For example, the distance between two locations can be remembered as longer than the true physical distance if the locations are separated by a boundary. While this overestimation is observed under different experimental conditions, even when the boundary is formed by flat surface cues, its physiological basis is not well understood. We examined the neural representation of flat surface cue boundaries, and of the space segregated by these boundaries, by recording place cell activity from CA1 and CA3 while rats foraged on a circular track or square platforms with inhomogeneous surface textures. About 40% of the place field edges concentrated near the boundaries on the circular track (significantly above the chance level 33%). Similarly, place field edges were more prevalent near boundaries on the platforms than expected by chance. In both one- and two-dimensional environments, the population vectors of place cell activity changed more abruptly with distance between locations that crossed cue boundaries than between locations within a bounded region. These results show that the locations of surface boundaries were evident as enhanced decorrelations of the neural representations of locations to either side of the boundaries. This enhancement might underlie the cognitive phenomenon of overestimation of distances across boundaries.

Primary Antiphospholipid Syndrome Presenting as Budd-Chiari Syndrome

Primary Antiphospholipid Syndrome Presenting as Budd-Chiari Syndrome

Inhomogeneous Texture Distributions Imaged by ACOM and X-Ray Pole Figure Measurement

The development of inhomogeneous texture in a deep-drawn aluminum cup and a friction welded aluminum roller has been investigated by ACOM (Automated Crystal Orientation Mapping) and compared with results from x-ray pole figure measurement and ODF analysis with triclinic sample symmetry. After deep drawing the diffracted x-ray intensities are drastically reduced to only about 15% of the initial one. and the spread range of the orientation components are expanded. The sharp cube component of initial texture was retained after deep drawing, but the weak β fiber has disappeared and some other components are formed. As another example texture changes by frictional bonding, the seam between two parts of a roller has been studied. The rollers were made of Al6061 and are used in textile industry. The texture was investigated by means of ACOM because the deformed zone during the welding is much narrower.

Evolution of texture and microstructure in a thermomechanically processed Al-Li-Cu-Mg alloy

The development of texture and microstructure in a thermomechanically processed quaternary Al-Li-Cu-Mg alloy has been investigated. Textures on both the surface (1/8 thickness (T)) and midthickness levels of specimens were measured using the conventional pole figure as well as the orientation distribution function (ODF) method. Microstructural characterization was carried out with the help of optical microscopy and transmission electron microscopy (TEM). The processing schedule involved hot cross rolling, followed by several stages of cold rolling (CR) with intermediate solution treatments (STs). A marked through-thickness texture inhomogeneity developed in the processed sheets during the course of thermo mechanical treatment (TMT). In general, the texture produced at the midthickness level was 2 to 3 times sharper than the texture at the surface.

Analysis of deformation texture inhomogeneity and stability condition of shear components in f.c.c. metals

The texture of cold rolled aluminum sheet has been known to vary through the thickness due to inhomogeneous deformation during rolling. The copper texture is obtained in the center layer that is plane strain compressed while the shear texture in the surface layer, which is approximated by major {001}〈011〉 and minor {111}〈112〉 and {111}〈110〉 components. The stability condition of these components was calculated based on the full constraint Taylor-Bishop-Hill theory and could be described by a parameter dɛ 13/dɛ 11 with the suffixes 1 and 3 indicating the rolling and thickness directions, respectively.

Deformation-dominated texturing of superconducting filament in OPIT-fabricated Bi(Pb)SCCO-2223/Ag composite tapes

Texture formation in the ceramic filament of Ag/BiSCCO tapes was studied after cold rolling, uniaxial cold pressing and sintering by XRD /spl theta/-2/spl theta/ and /spl omega/-scan methods. More effective texturing of the outer layers as compared to that of the core interior was observed at the early rolling steps up to about 65% reduction in area. Texture inhomogeneity over the filament cross section is related to the inhomogeneous distribution of plastic deformation. Work hardening due to plastic deformation of non-sintered powder results in the broadening of X-ray peaks and an increase in microhardness. The recovery of these parameters occurs after annealing at the temperatures of 350-600/spl deg/C. The /spl omega/-scan studies revealed an improvement of c-axis texture by intermediate rolling compared to that in the as-sintered and pressed states. Deformation-induced texturing of the 2212-precursor is the main factor responsible for the texture of the final 2223-phase. The influence of Ag during the sintering stage is limited only to the outer layers of the filament; in the case of low preliminary deformation internal layers remained practically non-oriented.