Diameter Of Grains Research Articles

Physical mechanism for nanocrystalline NiTi alloy with ultrasmall-sized grains exhibiting one-way shape memory effect without temperature-induced phase transformation

In the present work, a novel finding is that nanocrystalline NiTi alloy with ultrasmall-sized grains (where the diameter of grains is less than or equal to 10 nm) presents one-way shape memory effect (OWSME) without temperature-induced phase transformation, where the involved physical mechanism is revealed by combining experiments with molecular dynamics simulation (MD). The results show that fraction of grain boundaries (GBs) is so much that temperature-induced martensitic transformation is suppressed, but it leads to a certain unrecoverable strain. The following loading results in increase of strain and decrease of Gibbs free energy, which leads to stress-induced martensitic transition. After unloading, Gibbs free energy is increased by the release of elastic strain, which leads to partial reverse martensitic transition. Consequently, OWSME in nanocrystalline NiTi alloy with ultrasmall-sized grains is aroused by retained stress-induced martensitic transition followed by its reverse phase transition rather than temperature-induced one followed by its reverse phase transition.

A manufacturing method of rock samples with specific porosity and permeability for large-scale 3-D physical simulations

Making an artificial rock sample with specific porosity and permeability at a low cost to restore heterogeneous characteristics of target formation is significant to improving quality in large-scale 3-D physical simulations. To achieve this goal, the effects of effective stress of compaction (ESC), mass fraction of cements (MFC) and average diameter of grain (ADG) on porosity and permeability of rock samples are primarily analyzed by making 80 artificial core plugs using pressing synthesis technique. The results show that both ESC and MFC are negatively correlated with porosity and permeability. Meanwhile, if rock grains are enough homogeneous in size, only permeability is affected by ADG dramatically and the impact of ADG on porosity is not obvious. Based on the above achievements, two empirical models on the relationships between manufacturing parameters and porosity, manufacturing parameters and permeability are developed respectively, and then they are used to design a sub-meter scale rock sample and calculate its manufacturing parameters. Lastly, this rock sample is used to demonstrate the reliability of method by testing actual porosity and permeability. The validation indicates that absolute error between designing and actual porosity is 2.50% and absolute error of permeability is 20.30%. Manufacturing errors are lower than that of previous works. Additionally, production cost of rock samples is also very low and the total cost of the above sample is about 6000 CN Yuan (900 US Dollars). Thus, this method is reliable and it has great developing potential in large-scale 3-D physical simulations on fluid flow in porous media.

Microstructure evolution of ATI718 plus alloy during high-speed machining: Experiments and a combined FE-CA approach

Excellent surface integrity is an eternal pursuit in high performance manufacturing, with microstructure being a crucial component of the surface integrity dataset and a key factor controlling surface properties such as fatigue and creep. The multi-physical fields generated by thermo-mechanical loads during high-speed machining act on the processed surface layer, influencing the evolution of microstructures. To investigate the microstructural evolution mechanisms of ATI718 plus during high-speed machining, cutting experiments and techniques such as Electron back scatter diffraction (EBSD), Transmission Kikuchi diffraction (TKD), and Precession electron diffraction (PED) is conducted to quantitatively analyze the microstructures in the chip shear zone and the machined surface. Subsequently, a combined finite element (FE) and cellular automata (CA) model is developed to simulate the microstructure evolution during the cutting process. The discontinuous dynamic recrystallization (DDRX) mechanism is employed to demonstrate the nucleation and growth of grains under the influence of multiple physical fields. The simulation and experimental results show similar dynamic recrystallization (DRX) grain sizes, indicating acceptable accuracy of the CA model in terms of DRX grain size. The comparison between experimental and simulation results confirms the occurrence of both continuous dynamic recrystallization (CDRX) and DDRX during the cutting process. The synergistic competition between CDRX induced grain lamellar refinement and DDRX induced grain growth emerge as the primary mechanism driving microstructural evolution. A layer of ultrafine grains, with a thickness within 20 μm, is formed on the machined surface. Results under different parameters demonstrate that the temperature has a more significant impact on the thickness of the ultrafine grain layer and the diameter of grains within the layer compared to the strain rate.

Mining genomic regions associated with agronomic and biochemical traits in quinoa through GWAS

Quinoa (Chenopodium quinoa Willd.), an Andean crop, is a facultative halophyte food crop recognized globally for its high nutritional value and plasticity to adapt to harsh conditions. We conducted a genome-wide association study on a diverse set of quinoa germplasm accessions. These accessions were evaluated for the following agronomic and biochemical traits: days to 50% flowering (DTF), plant height (PH), panicle length (PL), stem diameter (SD), seed yield (SY), grain diameter (GD), and thousand-grain weight (TGW). These accessions underwent genotyping-by-sequencing using the DNBSeq-G400R platform. Among all evaluated traits, TGW represented maximum broad-sense heritability. Our study revealed average SNP density of ≈ 3.11 SNPs/10 kb for the whole genome, with the lowest and highest on chromosomes Cq1B and Cq9A, respectively. Principal component analysis clustered the quinoa population in three main clusters, one clearly representing lowland Chilean accessions, whereas the other two groups corresponded to germplasm from the highlands of Peru and Bolivia. In our germplasm set, we estimated linkage disequilibrium decay to be ≈ 118.5 kb. Marker-trait analyses revealed major and consistent effect associations for DTF on chromosomes 3A, 4B, 5B, 6A, 7A, 7B and 8B, with phenotypic variance explained (PVE) as high as 19.15%. Nine associations across eight chromosomes were also found for saponin content with 20% PVE by qSPN5A.1. More QTLs were identified for PL and TGW on multiple chromosomal locations. We identified putative candidate genes in the genomic regions associated with DTF and saponin content. The consistent and major-effect genomic associations can be used in fast-tracking quinoa breeding for wider adaptation across marginal environments.

Numerical and experimental research on axial injection end-burning hybrid rocket motors with polyethylene fuel

This study investigates the end-burning hybrid rocket motors with polyethylene fuel by the numerical simulation and experiment. Based on computational fluid dynamics, a numerical model is developed. The model is validated by two firing tests in this hybrid rocket motor, which uses oxygen and polyethylene as propellants. The results show that the numerical and experimental data are in good agreement, and the error of the chamber pressure is less than 2.63%. Based on the simulation mode, the blowoff limit of the end-burning hybrid rocket motors is investigated. When the nozzle throat diameter and the inner diameter of grain are large, it is more difficult for the hybrid rocket motor to achieve end-burning mode, i.e., the flame spreading is prevented in the narrow duct. The main reason is that when the nozzle throat and the grain port are large, chamber pressure and oxidizer flow velocity are low. Therefore, the friction velocity considering the pressure and flow velocity is proposed. The critical friction velocity is about 4.054–4.890 m/s in the hybrid rocket motors. When the friction velocity exceeds the critical friction velocity, the combustion mode in hybrid rocket motors changes from the flame spreading mode to the end-burning mode. Moreover, the regression rate formula is obtained by fitting, which shows that the regression rate has a good correlation with combustion chamber pressure. The critical friction velocity and regression rate formula can provide an important reference for end-burning hybrid rocket motors.

Grain quality indicators and their phenotypic variability of ancient varieties of Triticum aestivum in the mountains of Uzbekistan

Abstract. Ruziyev F, Djabbarov I, Olimjonova S, Niyozov U, Urokov S, Ishankulova D, Bakhadirov U. 2023. Grain quality indicators and their phenotypic variability of ancient varieties of Triticum aestivum in the mountains of Uzbekistan. Biodiversitas 24: 5995-6001. Today, creation of varieties of agricultural crops that are resistant to adverse environmental factors and produce stable crops under the influence of stress factors has become one of the most important issues in the world. In the following years, scientific and research work is being carried out on the wide use of the diversity of its genetic resources in the creation of new varieties of wheat (Triticum aestivum L.). In this regard, there are opportunities to use wild, semi-wild and ancient local forms of wheat with high protein and high gluten content to create varieties that meet modern production requirements. Therefore, it is important to evaluate the quality indicators of ancient varieties and the degree of phenotypic variation in the selection of wheat varieties that are resistant to adverse environmental factors, fertile and high-quality. This research work, aimed at researching ancient wheat varieties cultivated by the people living in the mountainous regions of Uzbekistan for many years. According to the research results, the grain quality indicators (grain hardness, diameter of grains, grain quality indicators, rheological properties, etc.) of the ancient wheat varieties distributed in the mountain regions are different. According to the results of the experiment, the grain hardness of the studied ancient wheat varieties is 73-82 µm, grain diameter 2.65-2.71 mm, hectolitre of weight 818.2-838.1±8.7 g/L, vitreousness 62.2-70.3%, gluten content in grain 31.5-34.6%, sedimentation index 64.4-77.2 mL. It was also observed that the phenotypic variability of the quality indicators was different in the wheat varieties that were the object of the study. Differences in the grain quality indicators of ancient wheat varieties are explained by the different effects of climatic parameters, abiotic and biotic factors in the regions where wheat grows. The information presented in the article provides an opportunity to select ancient wheat varieties distributed in the mountainous regions of Uzbekistan as starting sources for the creation of varieties with high nutritional value, resistant to adverse factors.

Structure design of porous TC4 alloy with excellent mechanical properties prepared by laser-powder bed fusion

Porous Ti6Al4V (TC4) alloy with a hexagonal structure (optimized side lengths of 700 μm and wall thickness ranging from 100 to 300 μm) was designed by finite element method (FEM) and prepared by laser-powder bed fusion (L-PBF) to improve mechanical compatibility. The porous TC4 alloys were composed of α′-Ti and a little β-Ti phases. The increasing wall thickness of the porous TC4 alloy induced the decrease in effective average diameter of grain from 1.97 to about 1.28 μm and the increase of average density of geometrically necessary dislocation (GND) from 4.46 × 1014 to 6.07 × 1014 m2. When the wall thickness was equal to or greater than 200 μm, the porous TC4 alloy exhibited high yield strength (about 550 MPa) and a proper elastic modulus of (14.4–15.4 GPa). This study could provide a reference for the material design of a new porous TC4 alloy with excellent mechanical properties.

Self-consistent homogenization approach for polycrystals within second gradient elasticity

In this paper, we propose a generalized variant of Kröner’s self-consistent scheme for evaluation of the effective standard and gradient elastic moduli of polycrystalline materials within Mindlin-Toupin second-gradient elasticity theory. Assuming random orientation of crystallites (grains) we use an extended Eshelby’s equivalent inclusion method and mapping conditions between the prescribed linear distribution of macro-strain and corresponding micro-scale field variables averaged over the volume and all possible orientations of single grain. It is found that the developed self-consistent scheme predicts an absence of gradient effects at the macro-scale level for the model of ellipsoidal grains made of the first gradient (Cauchy-type) material. However, for the case of the second gradient crystallites, established approach allows to obtain a set of non-linear relations for determination of all effective standard and gradient elastic moduli of polycrystals. Example of calculations under simplified constitutive assumptions is presented for the model of anisotropic cubic Fe crystallites with spherical shape. It is shown that the presented approach predicts an increase of the effective length scale parameter of polycrystalline aggregates due to misorientation of grains axes and takes into account the size effects related to the mean diameter of grains.

Critical Diameters of Grains or Individual Particles for the Start of a Martensitic Reaction from the Positions of Dynamic Theory

Critical Diameters of Grains or Individual Particles for the Start of a Martensitic Reaction from the Positions of Dynamic Theory

Effects of annealing temperature on a ZnO thin film-based ultraviolet photodetector

In this paper, the effects of annealing temperature on the performance of a ZnO thin film-based Metal-Semiconductor-Metal (MSM) type ultraviolet (UV) photodetector is reported. ZnO thin films were grown on a glass substrate using the Pulsed Filtered Cathodic Vacuum Arc Deposition (PFCVAD) technique at room temperature and after the deposition process the samples were annealed at 400, 450 and 550 °C in air condition to investigate the annealing effect on the structural, electrical, and optical properties of the photodetector. ZnO thin films which have grains in nanometer range has an increasing in the diameter of grains from 10.5 to 18.3 nm as a function of annealing temperature results in a red shift in the cut-off wavelength of the photodetector from 3.25 eV (381 nm) to 3.23 eV (383 nm). It is demonstrated that the sensitivity and the speed (rise/fall times) of the ZnO thin film based MSM photodetectors enhances with increasing post growth annealing temperature of ZnO thin film due to the increase in the absorption coefficient and the decrease of the total area of the grain boundaries due to the larger grain sizes formation in ZnO thin films with increasing thermal annealing temperature.

Effect of the inclusion features on mechanical properties of steel

ABSTRACT Polar steel requires good strength and excellent toughness for breaking icy surfaces in low-temperature sea water environments. In this study, the effect of inclusions and metallurgical structure on the mechanical property of polar steel was examined. The composition and morphology of the inclusions in steel were formed using different deoxidation methods during steel refining, and steel plates were rolled by the same rolling process. The results show that there are lower inclusion densities and more globular inclusions in steel deoxidized using Zr–Ti than deoxidized using Al. The mean diameters of grains in Zr–Ti-killed steel from different thicknesses are smaller than that in Al-killed steel, the impact toughness and yield strength of Zr–Ti-killed steel are substantially higher than those of Al-killed steel. It is determined that the use of the Zr–Ti deoxidizer has a positive effect on the ductility of the steel.

The Effect of pH on Stability of an Isolation Barrier Made of Dolomite Post-Floatation Waste

Dolomite post-floatation waste has been proposed as an alternative material for the construction of separation barriers. The aim of this study was to determine the effect of the pH of leaching solutions on the stability of such barriers. The present research included the determination of selected physical and chemical properties of waste, i.e., density, grain composition, and filtration coefficient. Column tests of leaching by solutions of different pH values modeling varying environmental conditions were performed. Selected ions were determined in the eluates. Grain analyses were carried out for the column material after leaching to determine the changes in grain composition of dolomite due to washing with leaching solutions. The determined value of the filtration coefficient is 6.52 × 10−9 m∙s−1, which confirms the impermeability of the waste. The material is fine-grained, with a grain diameter of d ≤ 200 µm. During leaching, a decrease in the content of the analyzed ions and the diameter of grains and their movement down the barrier, resulting in its sealing, was observed. The central part of all columns showed more grains with a diameter of 7 μm, which is probably due to secondary precipitation of CaSO4. Irrespective of the initial pH of the leaching solution, the reaction of all eluates obtained was slightly alkaline (pH 7.52–8.20). Dolomite post-floatation waste has properties that ensure the tightness and durability of the separation barrier, which, combined with its ability to alkalize solutions and the sealing process, ensures its effectiveness.

Shear modulus and reversible particle trajectories of frictional granular materials under oscillatory shear.

In this study, we numerically investigated the mechanical responses and trajectories of frictional granular particles under oscillatory shear in the reversible phase where particle trajectories form closed loops below the yielding point. When the friction coefficient is small, the storage modulus exhibits softening, and the loss modulus remains finite in the quasi-static limit. As the friction coefficient increases, the softening and residual loss modulus are suppressed. The storage and loss moduli satisfy scaling laws if they are plotted as functions of the areas of the loop trajectories divided by the strain amplitude and diameter of grains, at least for small values of the areas.

Nonparametric Methods in the Analysis of the Quality of Kernel of Selected Winter Wheat Cultivars

Abstract The paper presents a statistical analysis of weight and diameter of kernel obtained for eight investigated winter wheat cultivars. Preliminary analyses of experimental results, such as compliance with a normal distribution, equality of variance for particular cultivars, and occurrence of outliers proved that there is no justification for the use of a traditional one-way analysis of variance for verification of hypotheses according to which weight and diameter of grains of the investigated winter wheat cultivars do not differ. A nonparametric Kruskal-Wallis test was used for verification of hypotheses which based on the experimental results enabled to reject both hypotheses. Further, simultaneous average weight and diameters of grain of the investigated cultivars were compared with the use of Nemenyi-Dunn test. The applied test enabled to conclude which cultivars had a significantly higher weight than the others. Analogous comparisons were carried out for the diameter of kernels of the investigated winter wheat cultivars.

Facile preparation and characterization of novel manganese doped nickel oxide based nanostructured electrode materials for application in electrochemical supercapacitors

ABSTRACT Mn doped NiO nanostructured materials with composition Ni1-xMnxO1-δ (where x = 0.01, 0.03, 0.05, 0.07, 0.09) (MNO) were prepared by simple facile chemical synthesis route. The structural, particulate and microstructural characteristics of the Mn-doped NiO nanostructures were studied by studied by XRD, FTIR, particle size analysis, EDAX, SEM and HRTEM techniques. The XRD peaks of all the materials were indexed to the face-centred cubic (FCC) crystalline structure. FTIR spectra revealed the presence of NiO bending vibration mode between 432.07 to 492.83 cm-1. Particle size patterns and SEM photographs confirmed the presence of nanosized grains apart from few bigger sized grains. The diameter of grains was mostly found to be in the range of 30.04 to 591.16 nm. Presence of appropriate composition of elements was confirmed by EDAX data. Polycrystalline behaviour of Ni0.95Mn0.05O1-δ was exhibited by HRTEM data. The electrochemical phenomena of Ni1-xMnxO1-δ were studied by cyclic voltammetry (CV), galvanostatic charge – discharge and electrochemical impedance measurements in 6 M KOH aqueous solution. Among the samples studied, Ni0.95Mn0.05O1-δ electrode exhibited maximum specific capacitance of 369.6 Fg-1 at a current density of 0.5 Ag-1. From the characterization data, Mn-doped NiO nanostructures appear to be the good electrode materials for electrochemical supercapacitor applications.

Investigation of the Bonding Formation of a Plasma-Sprayed Cast Iron Splat on a Preheated Aluminum Substrate Using an Experimentally Based Numerical Simulation Method

In this study, the bonding formation of the cast iron splat deposited on a preheated aluminum substrate by atmospheric plasma spraying was investigated using a finite element method based on a heat transfer model built in a cylindrical coordinate system. To enhance the accuracy of calculations, thermal contact resistance (Rth) of the contact interface was incorporated into the calculation. A precise Rth value was obtained using a well-established relationship. The diameter of grains in the splat was determined by atomic force microscopy analysis. Furthermore, the physical parameters of the cast iron and the aluminum at different temperatures used in the simulation were calculated according to the composition of the materials. The calculations indicated that the interface temperature was below the substrate melting point during the entire observation period, confirming that no melting of the aluminum substrate had occurred. Thus, the formation of splat–substrate metallurgical bonding was attributed to the enhanced interface temperature and plastic deformation rather than the melting of the substrate surface.

Mapping dynamic QTL dissects the genetic architecture of grain size and grain filling rate at different grain-filling stages in barley

Grain filling is an important growth process in formation of yield and quality for barley final yield determination. To explore the grain development behavior during grain filling period in barley, a high-density genetic map with 1962 markers deriving from a doubled haploid (DH) population of 122 lines was used to identify dynamic quantitative trait locus (QTL) for grain filling rate (GFR) and five grain size traits: grain area (GA), grain perimeter (GP), grain length (GL), grain width (GW) and grain diameter (GD). Unconditional QTL mapping is to detect the cumulative effect of genetic factors on a phenotype from development to a certain stage. Conditional QTL mapping is to detect a net effect of genetic factors on the phenotype at adjacent time intervals. Using unconditional, conditional and covariate QTL mapping methods, we successfully detected 34 major consensus QTLs. Moreover, certain candidate genes related to grain size, plant height, yield, and starch synthesis were identified in six QTL clusters, and individual gene was specifically expressed in different grain filling stages. These findings provide useful information for understanding the genetic basis of the grain filling dynamic process and will be useful for molecular marker-assisted selection in barley breeding.

Effect of Grain Moisture Content on Popping Yield of Sorghum Genotypes

This paper aimed at providing popping characteristics of different red and white sorghum genotypes according to different moisture content at traditional methods of popping using high temperature for a short time (HTST). To increasing grain moisture level, seven sorghum genotypes - mutant and hybrid lines (M1(6282), 16113, 16121, 1641, 1643, 1651, 1673) were soaked to 0, 60, 120 and 180 min in distilled water. The popping rate and expansion ratio were recorded. The results showed that conventional method of popping is a good main to produce pops sorghum after increasing moisture of grains. Moistening of grains from 13-16 % increased 5.3-10.2% popping rate of all sorghum genotypes. The mutant line M1(6282) with red coloration of pericarp had the highest popping rate and expansion ratio at 16% moisture i.e. 85% and 3.88 %, respectively. There was correlation between diameter of grains and parameters expansion ratio (from 0.604 to 0.724), popping rate (from 0.815 to 0.878) and moisture grains (from 0.815 to 0.878).

Influence of chemical composition of fly-ash cenospheres on their grains size

Cenospheres, which are the by-product of hard coal combustion, are characterized by properties allowing for a broad use of this material. The article presents the results of the chemical composition analysis of the cenospheres obtained from various power plants. It has been exhibited that depending on the place of origin, their chemical composition is similar and comparable to fly ash produced in hard coal combustion. A great majority of analysed cenospheres may be classified similarly as the sialic ashes—slightly acidic. The analysis of dependence of refractoriness of the cenospheres on their chemical composition confirmed the correlation between this parameter and the content of SiO2 and Al2O3. At the same time, the content of each of the chemical components indicates a correlation with the size of the cenospheres. A trend of SiO2/Al2O3 ratio decreasing along with the increasing size of the cenospheres has been noted. Also the content of K2O and—to a lesser extent—Na2O decreases along with increasing diameter of grains. An inverse correlation was noted in case of Fe2O3. The higher the diameter of the grains, the higher the content of this component. In view of the obtained results, it should be assumed that the division of cenospheres into grain-size classes before further industrial use could extent the current range of use of this material.

Batch sorption experiments of cesium and strontium on crushed rock and biotite for the estimation of distribution coefficients on intact crystalline rock

The distribution coefficient (Kd) of radionuclides on bedrock is one of the key parameters used in the safety analysis of spent nuclear fuel repositories. Typically, distribution coefficients have been determined using crushed rock. However, recent studies have shown that crushing of the rock increases considerably the distribution coefficient compared with the values of intact rock. This study aimed to test if batch sorption experiments using different grain sizes (i.e. mean diameter of grains) can be used to evaluate the Kd of strontium (Sr) and cesium (Cs) on intact crystalline rock, which would decrease the needed experimental time compared with transport experiments. Here we report the results of the batch sorption experiments with crushed rocks and compare the results with those from a recent study performed using electromigration experiments with intact drill core samples (Puukko et al., 2018). The batch sorption experiments were done for rock samples from Olkiluoto, Finland, as a function of grain size and of Cs and Sr concentration. Furthermore, the specific surface areas of the same rock samples with different grain sizes were determined. It was shown that Cs distribution coefficients correlate with specific surface areas of the studied rocks and biotite, the correlation coefficient being 0.95. The Cs distribution coefficient was highest for biotite at about 0.1 m3/kg at 10−4 M cesium concentration and increased systematically to about 1 m3/kg at 10−8 M. Distribution coefficients for rocks were up to about two orders of magnitude lower, being lowest with the rock with the lowest biotite content (3.3%). The distribution coefficient of Sr varied from 0.04 m3/kg to 0.007 m3/kg and behaved in a different manner: it remained constant in two out of three studied rocks in the concentration range of 10−8-10−4 M and only in the case of one rock a decreasing trend was seen at the higher concentration range. It was also shown that batch sorption experiments overestimate the distribution coefficient in respect to intact rock. The decrease of the distribution coefficient as a function of grain size can be estimated using a power law function. It was also shown that estimation of distribution coefficients of Cs and Sr for intact rock by extrapolation of distribution coefficients determined for different grain sizes is not possible without increasing grain size, but in that case diffusion into the grains would also affect the results. A new method was developed for estimating the fraction of the inner surface area of the total surface area of crushed grains. For the mean grain sizes of 0.25 mm and 0.75 mm the fraction of the inner surface was found to be 35–70% and 60–90%, respectively. The inner specific surface area was highest with biotite at 1.2 m2/g and lowest with the rock with lowest biotite content (3.3%) at 0.07 m2/g. The surface area analysis revealed that crushing creates and/or allows access to additional inner surface area that is not measured in intact rock. Furthermore, it was demonstrated that sorption of Cs on crushed rock was dominated by mica minerals in multiple concentrations while the effect of mica minerals on the Kd of Sr was not as straightforward.