Typical Texture Research Articles

Evolution of microstructure and residual stress for a lead-frame Cu-2.13Fe-0.026 P (wt%) alloy

The evolution of the dislocation density, precipitates, texture, and residual stress in lead-frame Cu-2.13Fe-0.026 P (wt%) alloys were studied. All samples showed residual compressive stress. Moreover, the dislocation density and residual stress of the rolled sample are higher than those of the annealed sample. After annealing, the sample is mainly composed of restored grains, and the dislocation density not generated an order of magnitude decrease. This trend may be the reason why the residual stress still exists in the sample after annealing. In addition, the presence of pits around Fe3P particles may contribute to the generation of the residual stress. More importantly, the texture type of each sample is mainly Brass (011)< 211 > , S (123)< 634 > or Copper (112)< 111 > , and the recrystallized Cube (001)< 100 > texture is rarely found. Finally, the structural energy density (Ev) of different textures is calculated. It was found that the Ev of the Copper (112)< 111 > texture affects the variation of its volume fraction, thereby controlling the evolution of the residual stress.

Impacts of vertical variation of coal seam structure on hydraulic fracturing and resultant gas and water production: A case study on the Shizhuangnan Block, Southern Qinshui Basin, China

Hydraulic fracturing plays a vital role in the development of coalbed methane (CBM). Coal seam structures can, however, affect the fracturing operations, further affecting gas and water production from the coal seam. Within the research area—the Shizhuangnan Block, Southern Qinshui Basin, China—three types of coal body textures are relevant, including original, cataclastic, and granulated structure. This research describes the impacts of different coal seam types on fracturing operations and gas and water production. The results show that different types of coal seams have different impacts on hydraulic fracturing and the resultant production of gas and water. The coal seams are classified according to the vertical variation characteristics of the coal seam structures. The first type of coal seam (Type I) only develops the original and cataclastic coal structure. The effects of fracturing reconstruction for Type I are good. A high degree of coal breakage and fracture formation is observed. Gas production from CBM wells in Type I coalbeds is usually high because the water in the coal reservoir can be discharged smoothly at an early stage. The second type of coal seam (Type II) develops an additional layer of granulated coal compared with Type I. During the fracturing process, breakage of the coal seam is obvious, and the granulated coal can easily produce fine-grained coal that can block the pores and fractures, which causes an increase and fluctuation of oil pressure and can affect the effectiveness of fracturing. The gas production curve from CBM wells in Type II coal seams is mostly bimodal and water production depends on whether the pulverized coal blocks the pores and fractures. The third type of coal seam (Type III) develops two additional layers of granulated coal compared with Type I, with a greater proportion of granulated coal present. A low degree of coal breakage and fracture formation is observed, and fractures are easily blocked by pulverized coal. The effects of fracturing reconstruction for Type III are bad. Forming an effective seepage channel in this type of coal seam and extending the fracture to the far end is difficult. The gas production from CBM wells in Type III coal seams is usually low, and water production is generally low during the whole drainage period.

Effect of Textured Glasses on Conversion Efficiency in Dye-Sensitized Solar Cells

In this paper, three types of optical textured glass substrates were prepared at the glass/transparent conductive oxide interface using polydimethylsiloxane nanoimprint lithography to increase the conversion efficiency of dye-sensitized solar cells (DSSCs). There were three types of textures: nanotexture, microtexture, and micro/nano double texture. In terms of optical characteristics, it was confirmed that the reflectance of all of the textured glass substrates was lower than that of flat glass in the mean value of the 400–800 nm wavelength band. Further, the diffuse transmittance was higher than that of flat glass for all of the textured glass substrates, and the D-Tx was particularly high. DSSCs were fabricated using N749 and N719 dyes; their size was 6 mm2. The conversion efficiencies of the N749 DSSCs were improved by 11% for the N-Tx (η of 2.41%) and 10% for the D-Tx (η of 2.38%) compared with flat glass (η of 2.17%) DSSCs. On the other hand, the M-Tx did not improve it. The conversion efficiencies of the N719 DSSCs with textured glass substrates were improved by 7.5% for the M-Tx (η of 2.74%), 18% for the N-Tx (η of 3.01%), and 26% for the D-Tx (η of 3.22%) compared with flat glass (η of 2.55%) DSSCs.

Polar Solomon rings in ferroelectric nanocrystals

Solomon rings, upholding the symbol of wisdom with profound historical roots, were widely used as decorations in ancient architecture and clothing. However, it was only recently discovered that such topological structures can be formed by self-organization in biological/chemical molecules, liquid crystals, etc. Here, we report the observation of polar Solomon rings in a ferroelectric nanocrystal, which consist of two intertwined vortices and are mathematically equivalent to a {4}_{1}^{2} link in topology. By combining piezoresponse force microscopy observations and phase-field simulations, we demonstrate the reversible switching between polar Solomon rings and vertex textures by an electric field. The two types of topological polar textures exhibit distinct absorption of terahertz infrared waves, which can be exploited in infrared displays with a nanoscale resolution. Our study establishes, both experimentally and computationally, the existence and electrical manipulation of polar Solomon rings, a new form of topological polar structures that may provide a simple way for fast, robust, and high-resolution optoelectronic devices.

Mutagenic effectiveness and efficiency of ethyl methane sulphonate (EMS) mutagen in linseed (Linum usitatissimum L.)

Induced mutation study was carried out to study the mutagenic effectiveness and efficiency ofthe mutagen ethyl methane sulphonate (EMS) in two genotypes of linseed, Him Alsi-2 and Kangra Local. On the basis of survivalpercentage in M1 generation under lab conditionsthe LD50 dose for both genotypes was estimated. Only three doses (one higher and one lower dose to LD50) were selected for raising M2 generation. Effects of these concentrations were studied on various morphological characteristics. Mutagen EMS was effective and efficient in producing chlorophyll and viable macromutations in M2 generation. Three types of chlorophyll mutants i.e. albina, xantha and radina were observed. Different types of alterations in seed color, seed texture, flower shape and plant type were observed. The macromutations although are not very useful for plant breeding but help in determining the effective mutagen doses and have also known to play an important role in evolution. EMS concentrations showing maximum effectiveness and efficiency in both varieties were different indicating varietal sensitivity towards EMS.

Water flow within and towards plant roots—a new concurrent solution

Abstract Various analytical models that calculate the water flow either around or inside plant roots are available, but a combined analytical solution has not yet been derived. The classical solution of Landsberg and Fowkes for water flow within a root relates the second derivative of xylem water potential to the radial water influx term. This term can be linked to well-known steady state or steady rate-based solutions for computing soil water fluxes around roots. While neglecting lateral fluxes between local depletion zones around roots, we use this link to construct a system of continuous equations that combine root internal and external water flow that can be solved numerically for two boundary conditions (specified root collar water potential and zero distal influx) and one constraint (mean bulk matric flux potential). Furthermore, an iterative matrix solution for the stepwise analytical solution of homogeneous root segments is developed. Besides accounting for soil water flow iteratively, the intrinsic effect of variable axial conductance is accounted simultaneously. The reference and the iterative matrix solution are compared for different types of corn roots, soil textures and soil dryness states, which showed good correspondence. This also revealed the importance of accounting for variable axial conductance in more detail. The proposed reference solution can be used for the evaluation of different morphological and hydraulic designs of single or multiple parallel-connected roots operating in targeted soil environments. Some details of the iterative matrix solution may be adopted in analytical–numerical solutions of water flow in complex root systems.

ACOUSTIC CHARACTERISTICS OF SIDESCAN SONAR ALONG PROPOSED POWER CABLE ROUTE, DUMAI – RUPAT ISLAND

Cable power installation along the route with bedforms-sediment structures sometimes potentially to have problems in the future or near future. In order to mitigate the cable from exposure because of currents, it is important to know a detailed understanding of the seabed and its mobility. Seabed characteristics, either textures or sediment structures, could be interpreted from acoustic characters, one of which is based on sidescan sonar images. An automatic interpretation to classify seabed characteristics can be done by using an image processing software. Image processing has been done on sidescan sonar images along power cable route between Dumai and Rupat Island. The image processing was using simple textures and Grey-Level Co-occurrence Matrix (GCLM) textures. Manual interpretation of sidescan sonar images classifies the acoustic characters into six; (1) fine sand waves with ripple marks, wave length 2.5-4 meters, (2) fine sands, (3) fine sand waves with ripple marks, wave length 5-9 meters, (4) fine sand with ripple-mega ripples, (5) coarse sands with ripple-trawl marks, and (6) very fine sands. The results of automatic classification show that image processing with simple textures is unable to identify the textures and structures of sediments properly, but by combining simple texture classification and GCLM types of sediment textures and sediment structures are better identified. This classification results are in agreement with the results of manual interpretation of sidescan sonar images.

Selection of Drought-Tolerant Pasture Species under Varying Soil and Moisture Conditions in Bauchi State, Nigeria

Livestock production is an agricultural system that serves as humanity’s protein and calorie source. Its production is the main economic stay for some people and a complementary source for others. However, land misappropriation and draught constrain the sustainable production of pasture for feeding livestock. Further aggravated by farmer/herder clashes and wetlands extinction. The need for an experiment for the selection of the best pasture species in the Sudan Savannah region that can thrive well under diverse soil textures and moisture status becomes imperative. This trial was conducted in the screen house of Babcock University, objectively to test the performances of Sorghum almum, Andropogon gayanus, Brachiaria mulato and Centrosema pascuorum under Sand, Sandy Clay Loam, and Sandy Loam textures and four water regimes: 100%, 75%, 50%, and 25%. Standard agronomic recommendations were practised throughout the experiment. Data collected included plant height, fresh and dry shoot and root weights, number of leaves, and leaf length. Data generated were analyzed using ANOVA. According to the results, Sandy Loam soil (Soil type from Gamawa) was the best for supporting all the pasture species, followed by Sandy Clay Loam (Soil type from Zaki). S. almum outperformed other pasture species significantly irrespective of soil textural type and water stress level treatments, followed by B. mulato. For water levels; 100% and 75% had the most promising biomass outcome. Based on the results, a 75% water regime which represents 25% deficit of the actual crop water requirement is recommended for the production of the tested pastures in the area.

Investigation of the optimum preheating treatment parameters for extruded Mg–Gd–Y–Zn–Zr alloy using high-throughput experiments

The effects of different preheating treatments on the microstructure and mechanical properties of extruded Mg–13Gd–4Y–2Zn–0.5Zr (wt.%) alloys were investigated by using high-throughput experiments in this paper. The results showed that the solid solution and aging prior to extrusion (SAE) samples with heterogeneous microstructure had the best strength-plasticity synergy with ultimate tensile strength (UTS), yield strength (TYS) and elongation (EL) reaching 446.35 ± 3.1 MPa, 382.5 ± 2.5 MPa and 6.5 ± 0.8%, respectively. The formation of heterogeneous microstructures was mainly attributed to the weakening of the particle stimulation nucleation (PSN) effect by the dissolution of the primary Mg5RE phase during the solid solution process and the strong Zener pinning effect of the dynamic Mg5RE phase precipitation during the extrusion process, which inhibited grain boundary migration and grain growth. Optimum strength-plasticity synergy was due to fine grain strengthening, second phase strengthening, texture strengthening and heterogeneous deformation induced (HDI) strengthening. Strain gradients between deformed grains and dynamic recrystallized (DRXed) grains were generated during deformation process, in order to coordinate the deformation and generate more geometrically necessary dislocations (GNDs) within the deformed grains, resulting in a strong HDI effect. The increase in plasticity was mainly attributed to the change in texture type due to the rotation of the lattice, which promoted the activation of non-basal slip systems. This study provided an efficient and rapid method for probing optimal heat treatment parameters, aiming to reduce the influence of uncontrollable factors on experimental results and increase the rigor of the experiment.

Effect of annealing twins, strain-recrystallization processing and δ-phase fraction on microtexture and evaluation of mechanical properties of nickel-based superalloy 718

The Nickel-based superalloy 718 is a precipitation-hardened material, especially by the ordered and coherent phases γ” (Ni3Nb) and γ″ (Ni3 (Al, Ti)). In addition to these phases, precipitation of carbides and δ-phase is possible. This material has high strength, creep, and corrosion resistance at temperatures up to 650 °C. However, despite the alloy’s outstanding performance under harsh environments, research effort has been put into optimizing its properties and increasing the operation temperature. Manipulation of microstructural parameters such as grain boundary character distribution (GBCD), microtexture, second phase fraction, etc. is frequently betaken in order ot achieve better properties. In this context, this work aimed to assess the influence of Thermomechanical Processing on the recrystallization texture of the material and its influence on the alloy’s mechanical behavior. The material was submitted to four iterative processing routes, composed of deformation-heat treatment cycles. The alloy’s microtexture data were obtained through the Electron Backscattered Diffraction technique. Data processing was performed using the MTEX toolbox, where Orientation Density Functions were obtained for microtexture analysis. It was observed that the deformation imposed during thermomechanical processing significantly affects the recrystallization texture of the material so that smaller deformations induce the formation of typical recrystallization texture components; on the other hand, high degrees of deformation lead to a retained deformation texture after annealing. Mechanical properties were evaluated by depicting the influence of different strengthening mechanisms and δ-phase fraction on yield strength and ductility, respectively. It was observed that the main strengthening parameters for the alloy were grain boundaries and intrinsic resistance (Pierls-Nabarro and solid solution), meanwhile ductility was greatly influenced by δ-phase and ∑3n boundaries fractions.

Improving the Antifriction Behaviors of Steel by Hybrid Treatments of MoS2 and Surface Texture

Abstract: In the present paper, the composite coatings with MoS2 and graphite in the epoxy resin were deposited on the textured surface of steel by laser and wire-electrode cutting technology to improve the anti-friction behaviors of the steel. The influences of the content of MoS2 and graphite and the types of surface texture on the anti-friction behavior were studied systematically. The experimental results show that the textured specimens with 1 mm space line and pentagon shape pore exhibit low friction behaviors under dry friction. CoF (coefficient of friction) of the pore and line textured with high content of MoS2 and graphite is reduced by 27.7% and 42.3% under dry friction and by 30.0% and 33.3% under starved lubrication, respectively. CoF of the texture and coating duplex-treated steel is much lower than that of the untreated steel due to the solid lubrication of MoS2 and graphite under dry friction. The possible antifriction and antiwear mechanism is discussed. It is concluded that the duplex-treated steel with the texture and coating exhibits good anti-friction behaviors and the composite coatings with solid lubricant are beneficial to improve the tribological properties of steel under starved and dry friction testing conditions. It is shown that hybrid surface treatment with the texture and solid lubricant coating is an effective way to improve the tribological properties of steel. Solid lubricant coatings deposited on the textured surface can be applied to improve the antifriction behaviors of steel under starved lubrication and dry friction.

Microstructure Evolution and Deformation Behavior of Extruded Mg-5Al-0.6Sc Alloy during Room and Elevated Temperature Tension Revealed by Ex-Situ EBSD and VPSC.

In this study, the microstructure evolution and deformation behavior of the extruded Mg-5Al-0.6Sc (AS51) alloy during tensile testing at room temperature (RT) and 250 °C were investigated by electron backscattered diffraction (EBSD) characterization and Visco Plastic Self Consistent (VPSC) simulation. The results showed that a continuous hardening behavior of the alloy occurred during the deformation at RT, and a certain softening was caused by the occurrence of dynamic recovery (DRV) and dynamic recrystallization (DRX) in the late stage of deformation at 250 °C. The primary deformation mechanism at both RT and 250 °C was dislocation slip, with prismatic <a> slip being the dominant deformation mode, and no significant changes in grain size or texture type occurred. By identifying the activated twin variants, the results indicated that the selection of twin variants was closely related to the local stress concentration. The relatively low activation frequency of extension twinning at 250 °C is partly attributed to the fact that the consumption of dislocations by DRV and DRX can effectively relax the local stress concentration. Meanwhile, the DRX mechanism during the deformation of the alloy at 250 °C was mainly discontinuous dynamic recrystallization (DDRX), with a low recrystallization fraction.

Rapid Assessment of Rind Hardness in Sugarcane and Its Association with Biochemical Traits

Rind hardness in sugarcane plays a major role in lodging resistance, and internode borer resistance,screening of sugarcane for rind hardness is essential for reducing yield loss. In order to identify the suitability of soil penetrometer for rapid rind hardness measurement, the rind hardness testing was carried out in two sugarcane clones of different rind hardness variability viz., Co 13003 (hard rind type) and Co 14002 (soft rind type). The investigation was carried out by three methods viz., pendulum type impact test rig, texture analyzer,and soil penetrometer and theresults revealed that thehard rind type Co 13003 sugarcane clone was observed with significantly greater hardness. Significant correlation between the three methods for the rind hardness trait and among the three methods the soil penetrometer method of determination of rind hardness is easy and rapid. Two-way hierarchical cluster analysis of studied biochemical traits has revealed a better classification of hard-rinded and soft-rind sugarcane clones. The Co 13003 was recorded as least susceptible to borers with high rind hardness (&gt;200 psi), along with better fibre. The NG 77 a hard rind type clone was also observed with high lignin compared to soft rind Gungera.

Tension-compression asymmetric functional degeneration of super-elastic NiTi shape memory alloy: Experimental observation and multiscale constitutive model

The functional degeneration of super-elastic NiTi shape memory alloy (SMA) rods is investigated in the cyclic tension-unloading and compression-unloading experiments. The results show that the functional degeneration exhibits a strong tension–compression asymmetry, which originates from the initial 〈111〉 and 〈110〉 mixed textures along the axial direction of the rods, the polarity of martensite transformation, and the complex interaction between martensite transformation and dislocation slipping. Moreover, the dependence of functional degeneration on the applied stress level is discussed. To understand and predict the effect of initial texture on the cyclic deformation of polycrystalline NiTi SMA, a multiscale constitutive model is constructed at finite deformation. At the mesoscopic scale, two major inelastic deformation mechanisms, i.e., the transformation between austenite and martensite phases and the transformation-induced plasticity caused by the strain mismatch at the austenite–martensite interface, are considered. The total deformation gradient is multiplicatively decomposed into the martensite transformation, transformation-induced plasticity and elastic parts. The deformation gradient parts at the mesoscopic scale are obtained by upscaling these physical quantities at a smaller spatial scale (i.e., the microscopic scale). The proposed model is formulated within the framework of irreversible thermodynamics. The driving forces for martensite transformation and transformation-induced plasticity are derived according to the established Helmholtz free energy and Clausius-Duhem inequality. The complex interaction between martensite transformation and dislocation slipping, and the forward/reverse inheritance of dislocations caused by the moving austenite–martensite interfaces are considered. To calculate the overall cyclic responses of polycrystalline NiTi SMA at the macroscopic scale, the developed constitutive model is implemented into the finite element software ABAQUS/Explicit using a user-defined material subroutine. A polycrystalline representative volume element is constructed by introducing the initial 〈111〉 and 〈110〉 mixed textures observed in the experiment. By comparing the simulated results with the experimental data, the capability of the proposed model to predict the texture-induced tension–compression asymmetric functional degeneration is verified, and the influence of texture type on the cyclic deformation is discussed.

Determination of Maximum Accuracy of Concrete Textures as Natural Targets for Movement Tracking Through DIC

The use of natural targets is one of the obstacles to the extensive use of digital image cross-correlation for measuring movements in civil structures. Long distance measurement through image and without access to the structure itself, brings results in an improvement in accessibility, being the procedure cheaper and safer than common methods that require direct access to the measuring point. One of the most used materials in construction is concrete. Therefore, it is important to analyze its performance when using image cross-correlation. In this work, we have made a series of concrete probes with different production characteristics to have a representative variety of concrete surfaces. With them, we have studied their floor error in a cross-correlation procedure using different illumination and blur conditions, to evaluate the influence of those parameters on the results. All results are compared to those obtained using the conventional texture for image cross-correlation techniques, that is a pseudo-speckle target. All experiments are done in laboratory conditions to control all variables involved and to avoid the influence of other variables linked to open air conditions, such as atmospheric disturbances. As a result, we have determined the best conditions to use the natural concrete texture and we have quantified that using this texture leads to a decrease in the accuracy of the results from two to three times the one obtained with a typical pseudo-speckle texture.

The Role of Vegetation on Urban Atmosphere of Three European Cities—Part 1: Evaluation of Vegetation Impact on Meteorological Conditions

This study quantifies the vegetation impact on urban meteorology by means of the numerical model WRF (Weather Research and Forecasting model). The assessment was made for two months: July and January. These were considered as representative for the summer and winter seasons, for the reference year 2015 in three European cities: Bologna, Milano, and Madrid. Two simulations at 1 km resolution were conducted over the cities with and without the actual urban vegetation, called VEG and NOVEG, respectively, in the model input. Then, the impact of vegetation was evaluated as the difference between the two simulations (VEG-NOVEG) for temperature, relative humidity, and wind speed fields. In general, we found that, as can be expected, urban vegetation tends to cool the atmosphere, enhance the humidity, and reduce the wind speed. However, in some cases, areas with the opposite behaviour exist, so that no a priori results can be attributed to the presence of urban vegetation. Moreover, even when major impact is confined around grid cells where urban vegetation is present, changes in meteorological quantities can be observed elsewhere in the city’s area. The magnitude of urban vegetation impact is higher in summer than in winter and it depends on the city’s morphological peculiarities, such as urban texture and vegetation types and distribution: average July temperature variations due to the presence of urban vegetation reach peaks of −0.8 °C in Milano, −0.6 °C Madrid, and −0.4 °C in Bologna, while in January, the values range between −0.3 and −0.1 °C. An average heating effect of ca. +0.2 °C is found in some parts of Madrid in January. For relative humidity, we found increments of 2%–3% in July and 0.5%–0.8% in January, while a decrease in wind speed was found between 0.1 and 0.5 m/s, with the highest occurring in Madrid during July.

Decomposition decreases molecular diversity and ecosystem similarity of soil organic matter

Soil organic matter (SOM) is comprised of a diverse array of reactive carbon molecules, including hydrophilic and hydrophobic compounds, that impact rates of SOM formation and persistence. Despite clear importance to ecosystem science, little is known about broad-scale controls on SOM diversity and variability in soil. Here, we show that microbial decomposition drives significant variability in the molecular richness and diversity of SOM between soil horizons and across a continental-scale gradient in climate and ecosystem type (arid shrubs, coniferous, deciduous, and mixed forests, grasslands, and tundra sedges). The molecular dissimilarity of SOM was strongly influenced by ecosystem type (hydrophilic compounds: 17%, P < 0.001; hydrophobic compounds: 10% P < 0.001) and soil horizon (hydrophilic compounds: 17%, P < 0.001; hydrophobic compounds: 21%, P < 0.001), as assessed using metabolomic analysis of hydrophilic and hydrophobic metabolites. While the proportion of shared molecular features was significantly higher in the litter layer than subsoil C horizons across ecosystems (12 times and 4 times higher for hydrophilic and hydrophobic compounds, respectively), the proportion of site-specific molecular features nearly doubled from the litter layer to the subsoil horizon, suggesting greater differentiation of compounds after microbial decomposition within each ecosystem. Together, these results suggest that microbial decomposition of plant litter leads to a decrease in SOM α-molecular diversity, yet an increase in β-molecular diversity across ecosystems. The degree of microbial degradation, determined by the position in the soil profile, exerts a greater control on SOM molecular diversity than environmental factors, such as soil texture, moisture, and ecosystem type.

Enhanced strength of AlCoCrCu0.5FeNi high entropy alloy thin films reinforced by multi-phase hardening and nanotwins

High entropy alloy (HEA) thin films have become increasingly popular because they exhibit favorable properties but with lower material consumption. Here, this research demonstrates that annealing of AlCoCrCu0.5FeNi thin films results in multiphase hardening and the formation of nanotwins. HEA thin films were atmospherically annealed at different temperatures (300 – 700 °C) for 5 h. A thin dense oxide layer consisting of Al2O3 and Cr2O3 appeared at the top surface of the 700 °C annealed film. This oxide layer endows the HEA thin film with excellent antioxidant properties. As such, vacuum and inert gas might not be required for HEAs annealing process at up to 700 °C. A phase transformation was observed in the film annealed at 700 °C for 5 h from X-ray diffraction patterns. Results from transmission Kikuchi diffraction and energy dispersive X-ray spectroscopy mapping indicated the formation of three new phases, including the FeCo phase, Cr-rich phase and Cu nano-clusters. Variations also happened in HEA FCC matrix where two types of texture existed in the HEA FCC grains i.e., {012} <110> and {112} <110>. Of particular interest was that high-resolution transmission electron microscopy revealed a high density of annealing nanotwins among the HEA FCC grains, including lamellar and co-axial twins. The influence of these structural phenomena on mechanical properties was evaluated. The results showed that the hardness and modulus of 700 °C annealed HEA thin film increased by 25% and 24% to 8.4 ± 0.2 GPa and 149.4 ± 6.1 GPa when compared to the properties of as-deposited films.

Deformation behavior and dynamic recrystallization mechanism of a novel high Nb containing TiAl alloy in (α + γ) dual-phase field

Dynamic recrystallization (DRX), microstructure evolution and texture of high Nb containing TiAl alloys with a composition of Ti-43Al-6Nb-1Mo-1Cr (at.%) during the isothermal deformation are investigated in this paper. The recrystallized γ grains with L10 structure dominate the deformation in condition 1150°C/0.005 s-1. Meanwhile, the deformation-induced γ/α2→α phase transformation occurs in present TiAl alloy. Except the continuous dynamic recrystallization (CDRX) characterized by crystal orientation accumulation, lots of grains with specific 89±3° misorientation angles related to discontinuous dynamic recrystallization (DDRX) are observed in the γ phase. The specific misorientation angles might be caused by grains rotation, which is related to the activation of {111}<110> slipping system in γ phase. As regards as texture, the texture of α2 phase mainly maintains transverse texture during the deformation. And γ phase exhibits typical hot-rolled texture at low strain. With the strain increasing to 40%, the scattered texture appears, due to the nucleation of many dynamic recrystallized grains. The variety of texture is mainly caused by different DRX behaviors at various strains.

Phosphate Petrochronology of the Belcina REE Mineralization (Ditrău Alkaline Massif, Romania)

A notable REE mineralization in Europe is associated with the Ditrău Alkaline Massif (DAM) in the Eastern Carpathians (Romania). It is an expression of the latest hydrothermal phase in the DAM and is found in the form of mineralized carbonate veins cross-cutting the complex in the NW (Jolotca region) and the SE (Belcina region) parts of the DAM. In the Belcina veins monazite-(Ce), xenotime-(Y) and apatite, together with Fe-Mg-rich carbonate, thorite, thorogummite, gedrite and plagioclase are rock-forming. Three different textural and chemical types of the monazite-(Ce) and the xenotime-(Y) document a three-stage evolution. The relative phosphate age succession (from older to younger) thereby is xnt1 &gt; xnt2 (&gt;)+ mnz1 + Fe2O3 + Fe-gedrite &gt; mnz2 + Fe-dolomite (+ plagioclase) &gt; mnz3 + xnt3 + apatite. Phosphate chemistry shows that these crystallized from hydrothermal fluids, whereby each phosphate type follows a separate evolutionary path suggesting growth from (at least) three independent and successive hydrothermal fluids. Chemistry and pathways within the DAM suggest that these hydrothermal fluids could be derived from a subsurface carbonatitic intrusion. Mnz1,2 and xnt1,2 ages are tightly clustered at 215.8 ± 0.7 Ma (Norian, Upper Triassic). The third-generation phosphate ages are younger, but are associated with large analytical uncertainties and did not deliver geologically useful ages. The mean age of ca. 216 Ma is interpreted as the timing of the Belcina REE mineralization, which together with the fluid chemistry, supports a model of the presence of a late-stage, independent carbonatitic intrusion about 10 Ma after the main igneous activity (ca. 235–225 Ma) forming the DAM, synchronous with extension-related magmatism in the region.