Artificial Grain Research Articles

Superconducting (Ba,K)Fe2As2 epitaxial films on single and bicrystal SrTiO3 substrates

The realization of single crystal and bicrystal films of superconducting materials is of great interest because they allow the investigation of the intragrain performance as well as the understanding of potential limitations in the grain boundary transparency. For many years, the realization of a high-quality (Ba,K)Fe2As2 film has been challenging. Here, the realization of (Ba,K)Fe2As2 epitaxial thin films on single crystal SrTiO3(001) and [001]-tilt-type SrTiO3 bicrystal substrates with high superconducting properties is demonstrated. The epitaxial growth of (Ba,K)Fe2As2 was enabled by implementing an undoped BaFe2As2 buffer layer between the SrTiO3 substrate and (Ba,K)Fe2As2 film. The film exhibits a high Tc of 38.0 K and an extremely high Jc of 14.3 MA/cm2 at 4.2 K. Artificial grain boundaries of (Ba,K)Fe2As2 were also successfully achieved on bicrystals with misorientation angles up to 36.8° by the same preparation methods. The artificial grain boundaries exhibited an identical Tc of 38.0 K and an excellent transfer of the grain orientation from the bicrystal substrates with high crystallinity comparable to that of the high-quality Ba(Fe,Co)2As2 films. This enables the investigation of the intrinsic (Ba,K)Fe2As2 grain boundary nature, which will clarify its potential for superconducting applications, like Josephson junctions, wires, and magnets.

Stress analysis and dislocation cluster generation in silicon crystal with artificial grain boundaries

We conducted a dislocation and stress analysis on various grain boundaries (GBs) using silicon ingots that contained artificial GBs to permit systematic comparison of experimental and analytical results. Through photoluminescence imaging, we found that the number of dislocation clusters generated around the 〈110〉-oriented GBs was significantly higher than those around the 〈100〉-oriented GBs. The stress analysis revealed that this difference is linked to the maximum shear stress around the GB. However, there were some GBs where dislocation cluster generation was not observed despite the presence of high shear stress. For most of these GBs, the direction of the maximum shear stress in the 12 slip system of silicon crystal was found to be oblique downward to the growth direction, which appears to inhibit dislocation propagation.

Grain and grain boundary segmentation using machine learning with real and generated datasets

We report a significantly improved accuracy in grain boundary segmentation using Convolutional Neural Networks (CNN) trained on a combination of real and generated data. Manual segmentation is accurate but time-consuming, and existing computational methods are faster but often inaccurate. To combat this dilemma, machine learning models can be used to achieve the accuracy of manual segmentation and have the efficiency of a computational method. An extensive dataset of from 316L stainless steel samples is additively manufactured, prepared, polished, etched, and then microstructure grain images were systematically collected. Grain segmentation via existing computational methods and manual (by-hand) were conducted, to create ”real” training data. A Voronoi tessellation pattern combined with random synthetic noise and simulated defects, is developed to create a novel artificial grain image fabrication method. This provided training data supplementation for data-intensive machine learning methods. The accuracy of the grain measurements from microstructure images segmented via computational methods and machine learning methods proposed in this work are calculated and compared, and also provide benchmarks in grain segmentation. Over 400 images of the microstructure of stainless steel samples were manually segmented for machine learning training applications. This data and the artificial data is available on Kaggle.

Potential of Mechanical Grain Dryers in Addressing Exposure of Rice Farmers to Weather Risks

Weather risks brought by prolonged rainfall and cloudy days hamper grain drying operations in the Philippines as the majority still employ the sun drying method, which limits the opportunity of rice farmers to earn a higher income. While mechanical dryers are considered an important adaptation mechanism to address weather risks, more research needs to be done on their benefits and their disadvantages. This study adapted the Inter-governmental Panel on Climate Change (IPCC) concept which equates hazard, exposure, and vulnerability to quantify risk. Hazard was assessed in terms of the probability of four straight rainy- or cloudy-day occurrences based on a 30-yr daily rainfall and cloudiness data. Exposure of famers and traders to this event was described in terms of a cropping calendar followed by the farmers, while vulnerability was quantified in terms of the effects of exposure to continuous rains, particularly as price discounts for quality-degraded grains. About 74% of the total rice harvest in Isabela, Philippines is being dried using the sun drying method. Based on the probability of exposure to extended rainy/cloudy days and the qualitative losses as indicated by price penalty for quality-degraded grains, total qualitative losses amounting to 117 mt valued at PhP 407.17 million (USD 8.14 million) is incurred in the province every year. With artificial or mechanical grain dryers, exposure of rice farmers to prolonged rainfall or cloudy days that constrain sun drying operations can be minimized or eliminated.

K-doped Ba122 epitaxial thin film on MgO substrate by buffer engineering

Molecular beam epitaxy of K-doped Ba122 (Ba1−x K x Fe2As2) superconductor was realized on an MgO substrate. Microstructural observation revealed that the undoped Ba122 served as a perfect buffer layer for epitaxial growth of the K-doped Ba122. The film exhibited a high critical temperature of 39.8 K and a high critical current density of 3.9 MA cm−2 at 4 K. The successful growth of epitaxial thin film will enable artificial single grain boundary on oxide bicrystal substrates and reveal the grain boundary transport nature of K-doped Ba122.

Improving Superconductivity, Microstructure, and Mechanical Properties by Substituting Different Ionic Pb Elements to Bi and Ca Elements in Bi-2223 Superconductors

In this detailed study, the changes of microstructural, mechanical, and superconducting features of bulk Bi1.8Pb0.2Sr2.0Ca1.8Pb0.2Cu3Oy materials prepared at different milling time intervals (0.5 h ≤ x ≤ 8 h) were investigated in the most precise manner. The measurements of X-ray powder diffraction (XRD) and Vickers microhardness (Hv) were designed to scrutinize the bulk BSCCO samples. All the results of the measurements and calculations show that the characteristics responsible for the applications of the technology, industry, and engineering are significantly improved up to the 3 h milling time beyond that they tend to deteriorate. The enhancement of the characters is generally related to the transition from underdoped level of the (Bi, Pb)-2223 to the optimum level with the milling duration and this event approves that sufficient Pb nanoparticles penetrate the crystal structure. On the other hand, some of the reasons for the suppression in the superconducting properties are the presence of the porosity, disorder, defects, and the localization problem in the Cu-O2 consecutively stacked layers. In addition to those mentioned above, the other reasons are degradation in the crystallinity, reduction in the average crystallite size, and decrease in mobile hole concentration in the Cu-O2 layers. Similarly, the Pb inclusion rises the artificial random dislocations and grain boundary weak-links in the (Bi, Pb)-2223 superconducting system. Vickers microhardness measurements show that (Bi, Pb)-2223 bulk superconducting specimens exhibit typical indentation size behavior depending on the presence of both elastic and plastic deformations in the system. The results obtained from the hardness measurements have been analyzed by using Meyer law, PRS model, MPRS model, elastic–plastic deformation model, and Hays-Kendall approach. As a result, the Hays-Kendall approach was identified as the most successful model in describing the mechanical properties of the samples.

Improving the antioxidant status, fat-soluble vitamins, fatty acid composition, and lipid stability in the meat of Grass carp (Ctenopharyngodon idella Val) fed fresh ryegrass (Lolium multiflorum Lam)

Ctenopharyngodon idella (Grass carp) is one of the most widely produced species in aquaculture. This species is capable of feeding on forage crops and algae. However, few studies have investigated forage feeding in the production of this species. The aim of this work was to evaluate the impact of fresh Lolium multiflorum feeding on the fatty acid and antioxidant fat-soluble vitamin composition, antioxidant status, and lipid stability of C. idella meat. For this purpose, a 120-day feeding trial was conducted. Approximately 300 juvenile C. idella (7.97 ± 0.6 g and 8.82 ± 0.73 cm) were used. Two experimental diets were used: L. multiflorum Lam (annual ryegrass) forage, or pasture diet (PD), and artificial grain diet (GD). Juveniles of C. idella fed PD accumulated a greater concentration of EPA, DPA, and DHA fatty acids after 60 and 120 days (P < 0.05). Conversely, fish fed a grain-based diet accumulated higher omega 6 fatty acid content in their meat. The PD group meat had a higher content of α-tocopherol, lutein, β-carotene, and retinol than the GD group (P < 0.05). The action of these fat-soluble vitamins and micronutrients increased the FRAP and decreased TBARS in the meat of the PD group. These results suggest that L. multiflorum (ryegrass) feeding improves the quality of C. idella meat by increasing the fatty acids beneficial to human health, such as EPA, DPA, and DHA contents. In addition, this diet increases the antioxidant fat-soluble vitamin contents, thus not only improving the nutritional value of the meat but also contributing to lipid stability.

Effects of grain boundary structure and shape of the solid–liquid interface on the growth direction of the grain boundaries in multicrystalline silicon

The unique samples fabricated using seed crystals with artificial grain boundaries (GBs) allowed a systematic investigation of the effect of the macroscopic GB structure (orientation, asymmetric angle, Σ values) on the GB growth direction.

Modelling of the pulsed field magnetisation of a REBaCuO bulk with a superconducting weld

The Pulsed Field Magnetization (PFM) is a compact and fast method to magnetize superconducting bulks compared to quasi-static magnetization methods like field- or zero-field-cooling. However, the heat generation induced by the strong applied variable magnetic field during the PFM makes high trapped magnetic field harder to achieve. In order to make the REBaCuO bulks easier to magnetize by PFM, superconducting bulks including a superconducting weld are studied by considering the electromagnetic properties of the weld different from those of the bulk body. This artificial grain boundary obtained by superconducting welding method might increase the trapped magnetic flux without increasing the applied magnetic field. In this paper, we are modelling the superconducting weld behavior during PFM using a 3D finite element model with the software COMSOL Multiphysics. The simulations are based on an H-formulation from Maxwell’s equations and the heat diffusion equation. We analyse the impact of the critical current Jc of the weld on the trapped magnetic field.

An innovation in finite element simulation via crystal plasticity assessment of grain morphology effect on sheet metal formability

Experimental and numerical study regarding the uniaxial tensile test and the forming limit diagram are addressed in this paper for AL2024 with the face-centered cube structure. First, representation of a grain structure can be obtained directly by mapping metallographic observations via scanning electron microscopy approach. Artificial grain microstructures produced by Voronoi Tessellation method are employed in the model using VGRAIN software. By resorting to the finite element software (ABAQUS) capabilities, the constitutive equations of the crystal plasticity were utilized and implemented as a user subroutine material UMAT code. The hardening parameters were calibrated by a trial and error approach in order to fit experimental tensile results with the simulation. Then the effect of the changing grain size, the heterogeneity factor, and the grain aspect ratio were studied for a uniaxial tensile test to emphasize the importance of the microstudy behavior of grains in material behavior. Furthermore, the polycrystal plasticity grain distribution was employed in the Nakazima test in order to obtain the forming limit diagram. The crystal plasticity-driven forming limit diagram reveals more accurate strains, taking into account the involving the micromechanical features of the grains. An innovative approach is pursued in this study to discover the necking angle, both in tensile test or Nakazima samples, showing a good agreement with the experiment results.

Impact of intragrain spin wave reflections on nanocontact spin torque oscillators

We investigate the origin of the experimentally observed varying current-frequency nonlinearity of the propagating spin wave mode in nano-contact spin torque oscillators. Nominally identical devices with 100 nm diameter are characterized by electrical microwave measurements and show large variation in the generated frequency as a function of drive current. This quantitative and qualitative device-to-device variation is described in terms of continuous and discontinuous nonlinear transitions between linear current intervals. The thin film grain microstructure in our samples is determined using atomic force and scanning electron microscopy to be on the scale of 30 nm. Micromagnetic simulations show that the reflection of spin waves against the grain boundaries results in standing wave resonance configurations. For a simulated device with a single artificial grain, the frequency increases linearly with the drive current until the decreased wavelength eventually forces another spin wave anti-node to be formed. This transition results in a discontinuous step in the frequency versus current relation. Simulations of complete, randomly generated grain microstructures additionally shows continuous nonlinearity and a resulting device-to-device variation in frequency that is similar to the experimental levels. The impact of temperature from 4 K to 300 K on the resonance mode-transition nonlinearity and frequency noise is investigated using simulations and it is found that the peak levels of the spectral linewidth as a function of drive current agrees quantitatively with typical levels found in experiments at room temperature.

UKRAINEON THE WORLD MARKET OF LEATHER MATERIALS

Background. The problem of stable activity of domestic producers, in particular in the production of leather and footwear, is exacerbated by increasing global competition along with the loss of significant share of domestic and foreign markets. The regulating of the development of industrial production, domestic and foreign markets for light industry products is one of the most important tasks of the state today. Therefore, the assessment of the state of Ukraine’s foreign trade in the leather and leathermaterials market is important component for forecasting andshaping the development of domestic leather manufacturing. The aim of the work is to analyze the dynamics of Ukraine’s foreign trade on the leather materials market and to establish key directions for thedevelopment of Ukraine’s leather industry to increase the competitiveness of domestic products in an international environment. Materials and methods. Methods of analysis and synthesis, comparison and gene­ra­lization are used for work. Statistical data of the State Statistics Service of Ukraine, customs statistics of the State Fiscal Service of Ukraine, as well as data from the Inter­national Trade Center are used to study the leather market of various finishing methods in the world. Results. The analysis of foreign trade activities of the leather materials market showed that leather, additionally processed after tanning, significantly exceeds exports in imports, while tanned leather without processing in exports is ten times higher than im­ports. The analysis of world trade indicators determined that leather with a natural full grain surface is characterized by the greatest competitiveness against polished leather withan artificial grain surface. According to the indicators of foreign trade activity, Ukraine ranks third among the countries – leaders in world imports of leather with a natural full grain surface configuration in the form of halves. According to this commodity position, Ukraine ranks 13th in world exports. Conclusion. The analysis of Ukraine’s foreign trade on the leather materials mar­ket revealed the need of forming commodity and technological specializations of the domestic leather industry in accordance with the production of leather with a natural full grain surface from cowhides as the most competitive product in the international environment.

Structural and Electrical Properties of La&lt;sub&gt;0.7&lt;/sub&gt;Ca&lt;sub&gt;0.3&lt;/sub&gt;MnO&lt;sub&gt;3&lt;/sub&gt; /α-Fe&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;3&lt;/sub&gt; Composites

Colossal magnetoresistive (CMR) materials have huge potential in modern application and it has been widely used in magnetic sensing industry. From the literature, an incorporation of secondary insulating phase into mixed-valence manganites could improve its extrinsic effect especially low-field magnetoresistance (LFMR). However, nanoparticle addition could lead to substitution and diffusion with its parent compound. In this work, the structural and electrical properties of La0.7Ca0.3MnO3 (LCMO) were investigated by adding the α-Fe2O3 nanoparticle with ratio of 0.00, 0.05, 0.10, 0.15 and 0.20 as the artificial grain boundaries. The LCMO compound has been synthesised using sol-gel route. The samples were chosen to sinter at 800°C to obtain the pure LCMO phase by referring to the thermogravimetric analysis (TGA). The structural properties were investigated by an X-ray diffractometer (XRD) while electrical properties were measured by a four-point probe (4PP) system. XRD patterns showed the coexistence of two phases (LCMO &amp; α-Fe2O3). LCMO crystallised in orthorhombic structure with space group Pnma while α-Fe2O3 exhibited in hexagonal form with space group R-3c. As the content of α-Fe2O3 increases, the resistivity of the samples increases drastically. Nevertheless, the addition of iron oxide has no significant effect on the metal-insulator transition temperature (T­MI). From the XRD and 4PP analysis, it can be deduced that the α-Fe2O3 nanoparticles do not react with LCMO compound and successfully formed the La0.7Ca0.3MnO3 /α-Fe2O3 composites. The resistivity increases when the nano-sized α-Fe2O3 is added into LCMO nanocomposites due to the insulator nature of α-Fe2O3.

Fabrication of HTS Low-Noise Nanobridge Josephson Junction by Gallium FIB

High-temperature superconductor (HTS) Josephson junctions (JJs) are primarily based on artificial grain boundaries. Bi-crystal JJs are typically utilized in HTS superconducting quantum interference devices (SQUIDs). However, the performances of bi-crystal JJs depend significantly on the quality of the interface at the junction. In this study, we investigate a method for forming nanobridge JJs via gallium focused ion beam (FIB) irradiation. A 100-nm-thick YBa <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> Cu <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">7-</sub> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">δ</sub> was deposited on an MgO (100) substrate via pulsed laser deposition. An additional 20-nm-thick Au layer, which serves as a protection layer preventing ion damage during alignment, was deposited in situ. HTS microchannels with a width of 4 μm were defined via photolithography and argon ion milling. The HTS microchannel widths are decreased via FIB line scans to create nanobridges. The JJs are fabricated using two types of HTS thin films, in which one has a higher critical current density (J <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">C</sub> ) that the other. The fabrication process using the gallium FIB was optimized and nanobridges with a junction width of 80 nm were prepared. As a result, a better with higher J <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">C</sub> (5 MA/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> ) HTS films allowed for making junctions exhibiting up to five Shapiro steps at 77 K.

Effect of bimodal WC particle size and binder composition on the morphology of WC grains in WC–Co–Ni3Al cemented carbides

In addition to dispersed nanoparticles in the binder phase, the effect of Ni3Al on the growth mechanism of tungsten carbide (WC) grains is also essential for the fabrication of high-quality of cemented carbides. In this work, WC–Co–Ni3Al cemented carbides with different combinations of Co and Ni3Al binders was studied by using the original artificial bimodal WC grain size distribution. The WC particle sizes of medium 4 μm, fine 1 μm and ultrafine 0.2 μm were adopted. A series of WC–Co–Ni3Al alloys were firstly designed based on thermodynamic calculations and then liquid-sintered at 1450 °C for 1 h. Subsequently, the morphology and grain size distribution of WC grains were studied. By increasing the proportion of Ni3Al in the Co–Ni3Al composite binder phase, the solid–liquid interfacial energy increases significantly, which may provide a higher driving force for abnormal grain growth (AGG) through 2-dimension (2D) nucleation. However, the increase of Ni3Al proportion conversely greatly raises the energy barrier for the migration of W and C atoms into liquid binder phase, which finally retards the AGG of WC. Consequently, the AGG of WC decreases and the number of crystallites with blunt faces increases on WC particles with the increase of Ni3Al proportion, which can be well accounted for by the presently detected WC morphology evolution.

Atomic-Scale Mechanism of Grain Boundary Effects on the Magnetic and Transport Properties of Fe3O4 Bicrystal Films.

In strongly correlated materials, change of the local lattice configuration is expected to tune or even generate new properties otherwise in the ideal bulk materials. For highly spin-polarized materials, the spin-dependent transport is sensitive to the local magnetic structure. Here, the artificial grain boundaries (GBs) with different tilt angles are produced in Fe3O4 films using SrTiO3 bicrystal substrates. The saturation magnetization of Fe3O4 bicrystal films is enhanced. The detailed atomic structural results combining with density functional theory calculations reveal that the elongated FeA-O bond length at GBs resulting in the reduction of charge transfer reduces the FeA magnetic moments, which enhances the total magnetic moments of Fe3O4. The in-plane rotation of the Fe3O4 lattice on bicrystal substrates alters the magnetization processes. Especially, the Fe3O4 bicrystal film with a tilt angle of 22.6° shows strong in-plane magnetic anisotropy due to the zigzag GBs. The altered magnetic anisotropy of Fe3O4 bicrystal films enhances the anisotropic magnetoresistance. The findings reveal the mechanism of GBs on the magnetic and transport properties and manifest that the strategy of utilizing GBs can tune the physical properties in highly spin-polarized materials.

PLASMA-CHEMICAL METHOD OF GRAIN FUNGAL CONTAMINATION CONTROL

The experimental results on the effect of grain treatment with ozone-air mixture on the level of artificial grain contamination with micromycetes are presented. The contamination dynamics for 1000 kg of wheat grain contaminated with Penicillium nordicum and Aspergillus flavus and stored in the prototype grain storage unit in ozone environment for 6 months is shown. The study on the effect of ozone on the growth inhibition of Aspergillus flavus for maize grain and Penicillium verrucosum for wheat grain in a 100 dm3 silo is presented. The effect of ozone on the content of aflatoxins in maize grain additionally contaminated with Aspergillus flavus is studied. The efficiency of ozone technologies for large-scale grain storage, as well as for reducing fungal contamination and controlling mycotoxin content in food grains, is shown.

A Study of the HTS Josephson Junction Formed by a Ga Focused Ion Beam

High Temperature Superconductor Josephson Junctions (HTS-JJs) are based on artificial grain boundaries. However, the layout of HTS Superconducting QUantum Interference Devices (SQUIDs) on a bi-crystal substrate was restricted. Therefore, we considered to form low noise nano-bridge JJs by Ga Focused Ion Beam (Ga-FIB) irradiation. An 100 nm thick and 4 μm wide YBa2Cu3O7-δ (YBCO) micro-channels protected by a 20 nm thick Au protection layer were irradiated by line scans of Ga-FIB (Acceleration voltage: 40 kV, Beam diameter: ∼30 nm) and they were became normal conductivity except for the restricted region. In those nano-bridges, W N = 500 nm and fluence Φ = 2.0×1015 ions/cm2 of the nano-bridge was I C = 170 μA and we confirmed Shapiro steps by microwave irradiation of f RF = 2 GHz.

Modification of the content of n-3 highly unsaturated fatty acid, chemical composition, and lipid nutritional indices in the meat of grass carp (Ctenopharyngodon idella) fed alfalfa (Medicago sativa) pellets.

A 120-d feeding trial was conducted to determine the effect of alfalfa (Medicago sativa) feeding on growth and chemical composition, fatty acid content, and nutritional and lipid indices of the meat of grass carp (Ctenopharyngodon idella). Two experimental diets were used: alfalfa pellet (AP) diet and artificial grain diet (GD). Final weight, feed conversion rate, and protein efficiency ratio were significantly greater in the GD group (P < 0.05). However, no differences in the length and condition factor were observed. The composition of the meat differed between treatments. The protein content was significantly greater in the AP group (P < 0.05), while the lipid and cholesterol contents were significantly greater in the GD group (P < 0.05). A greater proportion of saturated, n-6 polyunsaturated, and n-6 highly unsaturated fatty acids was obtained in the GD group. The AP group accumulated a greater concentration of eicosapentaenoic (EPA), docosapentaenoic (DPA), and docosahexaenoic (DHA) acids (P < 0.05). The fatty acid composition of the meat determined a significant decrease in the thrombogenicity index and saturation index (S/P) in the AP group (P < 0.05). The Elongase index was greater in the GD group (P < 0.05). In contrast, the AP group had a greater index of Δ9 Desaturase and Δ5 + Δ6 Desaturase for n-3 and n-6 fatty acids (P < 0.05). These results suggest that alfalfa feeding decreases the growth of C. idella but improves the quality of meat by increasing the protein, EPA, and DHA contents. It also reduces cholesterol content and improves nutritional indices.

Influence of Finite Mobilities of Triple Junctions on the Grain Morphology and Kinetics of Grain Growth

Grain boundary networks composed of equal microstructural elements were investigated in a recent paper. In this work a more complicated artificial grain topology consisting of one four-sided, two six-sided and one eight-sided grain is designed to further investigate the influence of grain boundary and triple junction mobilities on the kinetics of the system in more detail. Depending on the value of the equal mobility of all triple junctions, the initially square-shaped four-sided grain changes its shape to become more or less rectangular. This indicates that the grain morphology is influenced by the value of the mobility of the triple junctions. It is also demonstrated that a grain arrangement with low mobility triple junctions controlling the kinetics of grain growth enhances growth of the large eight-sided grains. In addition, grain growth is investigated for different values of mobilities of triple junctions and grain boundaries. A strong elongation of several grains is predicted by the modeling results for reduced mobilities of the microstructural grain boundary elements. The two-dimensional modeling results are compared to micrographs of a heat-treated titanium niobium microalloyed steel. This feature, namely the evolution of elongated grains, is observed in the micrograph due to the pinning effect of (Ti, Nb)C precipitates at elevated soaking temperatures of around 1100 °C. Furthermore, the experiments show that a broader distribution of the grain sizes occur at 1100 °C compared to soaking temperatures, where pinning due to precipitates plays a less prominent role. A widening of the distribution of the grain sizes for small triple junction mobilities is also predicted by the unit cell model.