bluuebunny/crossref_metadata_2025 huggingface dataset:
Design and development of keratin/chitosan/glucosamine sulfate composite loaded MWCNT intended for osteoarthritis drug delivery
Authors: Srinivasan Venkataramanan , Palanisamy Ponnusamy
Published: May 2023

Osteoarthritis (OA) is an inflammatory disease that affects the cartilage and tissues around the joints, which results in excessive pain and stiffness. One of the most critical challenges for improving the therapeutic effect in OA treatments is the current drug design utilizing functional polymers. Indeed, there is a need to design and develop novel therapeutic drugs for positive outcomes. In this view, glucosamine sulfate is a drug used to manage OA because of its potential therapeutic effects on cartilage and ability to inhibit disease progression. This research aims to develop a keratin/chitosan/glucosamine sulfate (KRT/CS/GLS) composite loaded functionalized multi-walled carbon nanotubes (MWCNTs) as a potential carrier for the treatment of OA. The nanocomposite was developed using various ratios of KRT/CS/GLS, and MWCNT. Molecular docking analysis has been performed with (D-glucosamine) and targeted proteins (Protein Data Bank ID: 1HJV, 1ALU) to determine the binding affinity and interactions. Field emission scanning electron microscopy study showed that the composite KRT/CS/GLS incorporated on the surface of functionalized MWCNTs effectively. Fourier transform infrared spectroscopy analysis confirmed the presence of KRT/CS/GLS in the nanocomposite and remained intact. X-ray diffraction analysis indicated that the nature of the composite in MWCNT transformed from a crystalline to an amorphous state. Thermo gravimetric analysis revealed that the nanocomposite has a high thermal decomposition temperature of 420 °C. The MTT assay results showed that 83% of cell viability has remained in RAW 264.7 cells at the maximum concentration (500 μg ml−1) of MWCNT-GLS/KRT/CS nanocomposite. Also, molecular docking results revealed the excellent binding affinity of D-glucosamine to each protein structure (PDB ID: 1HJV and 1ALU).
Canopy responses of Swedish primary and secondary forests to the 2018 drought
Authors: Wolf Julika , Asch Johanna , Tian Feng , Georgiou Katerina , Ahlström Anders
Published: May 2023

Boreal forest ecosystems are predicted to experience more frequent summer droughts due to climate change, posing a threat to future forest health and carbon sequestration. Forestry is a regionally dominant land use where the managed secondary forests are typically even-aged forests with low structural and tree species diversity. It is not well known if managed secondary forests and unmanaged primary forests respond to drought differently in part because the location of primary, unmanaged, forests has remained largely unknown. Here we employed a unique map detailing over 300 primary forests in Sweden. We studied impacts of the 2018 nationwide drought by extracting and analyzing a high-resolution remote sensing vegetation index over the primary forests and over buffer zones around the primary forests representing secondary forests. We controlled for topographical variations linked to soil moisture, which was a strong determinant of drought responses, and analyzed Landsat-derived EVI2 anomalies during the drought year from a multiyear non-drought baseline. We found that primary forests were less affected by the drought compared to secondary forests. Our results indicate that forestry may exacerbate the impact of drought in a future climate with more frequent and extreme hydroclimatic events.
Leveraging LiDAR for smart cities climate change resilient: A solar potential case study in a developing area
Authors: A Rahman S A F S , Maulud K N A , Hassan H
Published: May 2023

Smart cities and solar energy are crucial components in climate change adaptation and sustainability. The interrelation with United Nations Sustainable Development Goals (SDGs) based on the 7th SDG goal, Affordable and Clean Energy for solar energy, and the 11th SDG goal, Sustainable Cities and Communities for smart cities, catalyze the research in this field. Unfortunately, there are some gaps in integrating smart cities and solar energy, especially in the elevation model and solar potential accuracy factors. It is essential because the highly accurate integrated model is enormously beneficial, especially for stakeholders. Therefore, this study is leveraging the Light Detection and Ranging (LiDAR) technology to provide high-resolution datasets for elevation models and create a precise 3D urban environment model for resilient integrated smart cities climate change. Digital terrain, including Digital Terrain Model and Digital Surface Model, were developed based on precise LiDAR point clouds before two vital surfaces, building rooftops and land parcels, were treated as a fundamental surface for solar potential calculation. The solar potential Return of Investment rate was classified and integrated with the 3D urban environment model. This 3D urban environment model helps visualize and provides a more specific and coherent picture of reality. The potential application of LiDAR data in climate change adaptation and sustainability that can be linked using various technologies and scales is also demonstrated in this study.
Recovery of forest structure dynamics following selective logging in lowland dipterocarp Peninsular Malaysia
Authors: Ghazali N M , Said M N M , Kamarulzaman A M M , Saad S N M
Published: May 2023

The selective management system (SMS) practised in Malaysia has emerged to optimise the sustainability of permanently reserved forest management. SMS requires a management regime (felling) to ensure economical harvesting and appropriate residual stands for the logging cycle, including ecological balance and environmental quality. SMS includes a Post-Felling Forest Inventory (Post-F) sequence. Post-F is used to obtain information on the remaining stands and other plants to determine the silvicultural treatment of a logged area. However, data gathered from Post-F are insufficient to track and collect information on forest structure dynamics recovery after logging. Thus, this study is to further understand the applicability of remote sensing technologies for forest recovery structure assessment after selective logging in the lowland dipterocarp forest of Peninsular Malaysia. Understanding the structural and composition changes occurring in lowland dipterocarp forests is vital for forecasting these ecosystems in the future. This study uses temporal dynamics (5, 9, 16, 26 and 32 months) of canopy cover images obtained from Landsat 8 after selective logging. Using the Carnegie Landsat Analysis System (CLASlite), this study applies Automated Monte Carlo Unmixing Analysis (AutoMCU) algorithm to derive per-pixel fractional cover estimates of photosynthetic vegetation (PV), non-photosynthetic vegetation (NPV) and bare soil. The relationship between these three indicators has shown the dynamic growth pattern of the forest area after logging. Differences can be seen via changes in the PV, NPV and bare soil image over various time periods. The information derived from this study is vital for forest conservation strategies after logging, thus enhancing Sustainable Forest Management in Peninsular Malaysia.
Spatio-temporal analysis of land use and land cover changes in Nguru Wetland, Yobe State, Nigeria
Authors: Hassan G , Syakir M I
Published: May 2023

Rapid urbanization in Nguru has recently contributed to significant land use/land cover (LULC) changes, the purpose of this research is to study the spatio-temporal trends of LULC changes in Nguru LGA, Yobe State, Nigeria. The factors that contributed to LULC changes are: bio-physical impacts, desertification, sand-dunes encroachment, loss of vegetal cover, a decrease in bird population, climate change, the conversion of farmlands to built-up areas, accumulation of pollutants in flood risk disaster and decrease in annual rainfall. We used Multi-temporal Landsat data to analyze the LULC pattern in the study area based on 20 years data. Results showed a significant urban expansion, with built-up area increased from 446 hectares in 2001 to 768 hectares in 2011 and 2,483 hectares in 2021. The green area’s land area decreased from 7932 hectares in 2001 to 6,404 hectares in 2011 and 365 hectares in 2021. These findings may provide a snapshot of the LULC trends from spatial-temporal perspective of which useful to the conservationists, urban planners, environmental managers and decision makers in implementing sustainable land-use management and strategies for the study area. The Nigerian government’s environmental regulations for wetlands and lakeshore aimed to protect wetlands as habitats for various animal and plant species, ensure the conservation and responsible use of wetlands and their resources in Nigeria, and ensure water catchments are protected and floods are monitored.
Conversion of Imperata cylindrica, plastic face mask and mango peels to solid fuel briquette
Authors: Jalil N A A , Mokhtaruddin N A , Chia C H , Ahmad I K , Saad M J , Sarif M
Published: May 2023

The demand for briquette is rising with the increasing of urbanization. Briquettes is mainly used as fuel and heating component. In addition, briquette is used in various industries for over the years. In this study, Imperata cylindrica and mango peels along with face mask were anticipated to boost the properties of the solid fuel briquette. Proximate analysis (moisture content, ash content, volatile matter and fixed carbon) and ultimate analysis (CHNS and calorific value) conducted for the briquette samples before and after the carbonisation process. The characteristics and properties of face mask, mango peels, and Imperata cylindrica are significant for the contribution of the optimal ratio of solid fuel briquettes made from these combination materials. Based on the findings, it can be concluded that briquettes made from Imperata cylindrica: mango peel produce the best results. The findings indicate that the briquette has low moisture content, 3.0%, high volatile matter, 37%, low ash content, 5.7%, and high fixed carbon, 54.8%. The analysis of carbon, hydrogen, nitrogen, and sulphur (CHNS) found that carbon content is 68.8%. The contents of hydrogen, sulphur, and nitrogen were 4.5%, 0.3%, and 0.96%, respectively. The calorific value obtained was 24.2 MJ kg-1.
An overview of economic valuation of ecosystem services in protected areas and its roles in achieving Sustainable Development Goals (SDGs)
Authors: Al-Saedi T K , Syakir M I
Published: May 2023

Protected areas (PAs) provide a variety of benefits and services related to human welfare, poverty alleviation, and sustainable development. However, economic valuations of PAs are poorly measured to date. The majority of PAs management policy frameworks are based on biodiversity conservation. The purpose of this overview is to highlight the importance of PAs in achieving Sustainable Development Goals (SDGs) by reviewing current and past studies related to the economic value of ecosystem services and the valuation methodologies of PAs at local, regional, and national levels. In addition, the role of PAs in enhancing the sustainability of ecosystem services has been discussed. Furthermore, two case studies related to the ecosystem-economic perspective of PAs; Australia’s Great Barrier Reef and India’s Nagarhole Park, were highlighted. In general, the economic value of PAs is based on the components of ecosystem services, such as provisioning, regulating, supporting, and culture. The management of PAs is critical for valuation of species conservation as one of the standards derived from the ecosystem services. Additionally, it improved the level of financial income of the communities, their educational and health levels, revitalizing local businesses and providing job opportunities through the success of PA’s management strategies as local, national, and international tourist destinations. This review provides a snapshot of the roles of PAs in achieving Sustainable Development Goals (SDGs), useful for future researchers, planners, park managers, and policymakers to develop policies for sustainable investment and improvement of PAs.
The effect of physical properties of sandstone on the compression strength of rock
Authors: Shulhin K , Aprillah B , Alpiana  , Rahmawati D , Salsabila A A , Iqbal M
Published: May 2023

Sandstone are commonly found on Lombok Island. The research aims to determine the sandstone’s physical and mechanical properties against the uniaxial compressive strength test. Analysis of physical properties for this research was carried out to determine the dimensions of size, moisture content, specific gravity, and bulk density, while the analysis of mechanical properties was to obtain compressive strength values. The original dry and wet bulk weights were obtained by testing the physical properties and compressive strength of sand and trass. The results from the samples in the Gunung Jae show that the average water content was 8.275%, the specific gravity was 2.37 grams, the bulk density was 0.485 gr/cc, and the compressive strength test was the highest value of 14 mm with the stress of 0.18 MPa.
Research on The Impact of Ciliwung River Water on The Surrounding Environment in The DKI Jakarta Area
Authors: Rajagukguk J R , Pranoto D A
Published: May 2023

Ciliwung River flows through central Jakarta, passing through many residential and densely populated areas that cause heavy pollution in the Ciliwung River resulting from wastewater and solid waste. This research aims to know the water quality and pollution level in the Ciliwung river and determine the locations to install water quality online monitoring stations. The research method used in this study is to analyze the quality of water samples taken from several points of the Ciliwung River. The analysis results show that the Ciliwung river is highly polluted, especially in the areas going downstream of the river. In addition, the analysis results have determined 8 (eight) points/locations where the online water quality monitoring devices will be installed. Due to limited funds, however, only 3 (three) online monitoring devices are currently installed on site, representing upstream, middle, and downstream areas of the Ciliwung river.
The inherent strain method for additive manufacturing: critical analysis and new inherent strain rate method
Authors: Bellet M , Keumo Tematio J , Zhang Y
Published: May 2023

To reduce computation time, the inherent strain (IS) method is popular. It consists in adding layers, at room temperature, with an “inherent strain” representing the plastic deformation undergone during deposition. An IS method is developed, including a direct determination of the IS tensor based on the transient thermo-elastic-viscoplastic (TEVP) simulation. Validation is achieved: taking full-field inherent strains, the IS method allows retrieving TEVP predictions. However, application to a full part, for which a set of inherent strains must be conserved all along the construction, leads to poor results, far from TEVP. As an alternative, a new “inherent strain rate” (ISR) method is proposed, consisting in linearizing TEVP resolutions. Combined with an on-line learning technique, this strategy leads to results identical to TEVP reference, with still a significant speed-up. This makes the proposed ISR method very promising.
A 3D Multiscale Model for Prediction of the Microstructure Evolution in Ti6Al4V Components Produced by Laser Powder Bed Fusion
Authors: Nastac Laurentiu
Published: May 2023

A transient 3D multiscale model has been created to simulate the evolution of solidification microstructures rapidly and effectively in Ti6Al4V parts produced through Laser Powder Bed Fusion (LPBF). The microstructure simulation tool has been enhanced to account for rapid solidification conditions in Ti6Al4V alloys during processing of multi-layer multi-track LPBF parts. The simulation tool can evaluate the impact of part geometry, lase power input, laser speed, and laser beam shape on the formation of the microstructure in LPBF-processed Ti6Al4V alloy. The multiscale model considers several factors, including preferential crystallographic growth direction, isomorphism, epitaxy, melt pool motion, and temperature gradients to generate the observed texture and morphology of the microstructure in Ti6Al4V components. The model can evaluate various microstructure characteristics, such as grain size and texture. Consequently, it could aid in controlling the formation of solidification microstructures in Additive Manufacturing (AM) processed parts. The simulation tool has been previously validated by using IN625 laser remelting experiments made by National Institute of Standards and Technology. The 3D simulation tool can also be utilized to predict the microstructure formation in Ti6Al4V components produced by the Electron Beam AM processes.
Simulation of the solute transport and microstructure evolution during the selective laser melting process
Authors: Ren Neng , Li Jun , Panwisawas Chinnapat , Xia Mingxu , Dong Hongbiao , Li Jianguo
Published: May 2023

Selective laser melting is of great expectation to be used in additive manufacturing of aerospace components with complex geometry. However, there are still defects in the built parts, such as solutal segregation and unexpected microstructure, which contribute to cracks and lead to failure. At present, most of the simulations focus on the macroscopic grain structure, and the solute transport process has not been well demonstrated yet. In the present work, we develop a two-way fully coupled model based on cellular automaton and finite volume method to simulate the solute transport and dendritic structure evolution during the melting and solidification of the SLM process. The results reveal the microstructural evolution and solute transport during the melting, spreading, and smearing of the powder. The proposed model framework shows good potential to be applied to further numerical investigation on the solidification behaviours of the SLM process.
Thermo-mechanical modelling of additive manufacturing: activation of non-constructed domain and effect of kinematic hardening
Authors: Keumo Tematio J , Ravix L , Zhang Y , Bellet M
Published: May 2023

A thermo-mechanical finite element model is developed for additive manufacturing by directed energy deposition (DED). The simulation is conducted at the part scale by modelling the progressive deposition in the way of the fraction of the layer. To incrementally resolve the displacement, strain, and stress fields, a theoretical formulation for the kinematic positioning is proposed to minimize the distortion of the non-constructed fraction by considering current displacement and strain in the constructed part, which can resolve the discontinuous problem at the interface for a patch of material depositions. Moreover, it is found that the kinematic hardening couldn’t be ignored for the back-and-forth deposition mode of the DED process. The application for a turbine blade with a strong curvature is adopted, and the distributions of distortion and stress during mid-construction and final construction are studied.
A 3D simulation of grain structure evolution during laser rescanning process of powder bed fusion additive manufacturing
Authors: Kang K , Yuan L , Phillion A B
Published: May 2023

Laser powder bed fusion (LPBF) is an extensively used additive manufacturing process that can build metal parts with complicated geometric designs. However, because of the rapid solidification conditions and the layer-by-layer building, its application is challenged by products having poor surface quality and reduced mechanical properties. The laser rescanning process is often used as a refinement method during LPBF to improve the quality of products. In this study, grain structure formation during the LPBF laser rescanning process is modelled by a 3D cellular automaton based microstructure model coupled with finite element analysis. The coupled model considers different nucleation mechanisms, including epitaxial growth, which are applicable to rapid solidification in melt pool. The model is adapted to reproduce the grain structure and evolution of an Al-Si alloy manufactured by LPBF utilizing a laser rescanning strategy. The effects of laser remelting on the characteristics of the grain structure (i.e., the grain size, aspect ratio and orientation) are evaluated. The mechanisms that enable unique grain structure (i.e., grain refinement) are discussed.
Phase-field study of polycrystalline growth and texture selection during melt pool solidification
Authors: Tavakoli Rouhollah , Tourret Damien
Published: May 2023

Grain growth competition during solidification determines microstructural features, such as dendritic arm spacings, segregation pattern, and grain texture, which have a key impact on the final mechanical properties. During metal additive manufacturing (AM), these features are highly sensitive to manufacturing conditions, such as laser power and scanning speed. The melt pool (MP) geometry is also expected to have a strong influence on microstructure selection. Here, taking advantage of a computationally efficient multi-GPU implementation of a quantitative phase-field model, we use two-dimensional cross-section simulations of a shrinking MP during metal AM, at the scale of the full MP, in order to explore the resulting mechanisms of grain growth competition and texture selection. We explore MPs of different aspect ratios, different initial (substrate) grain densities, and repeat each simulation several times with different random grain distributions and orientations along the fusion line in order to obtain a statistically relevant picture of grain texture selection mechanisms. Our results show a transition from a weak to a strong ⟨10⟩ texture when the aspect ratio of the melt pool deviates from unity. This is attributed to the shape and directions of thermal gradients during solidification, and seems more pronounced in the case of wide melt pools than in the case of a deeper one. The texture transition was not found to notably depend upon the initial grain density along the fusion line from which the melt pool solidifies epitaxially.
Modeling residual stresses of functionally graded deposits using the PTAAM
Authors: Bonias Geoffrey , Henein Hani , Wolfe Tonya B.
Published: May 2023

High maintenance costs due to significant abrasive wear of components is experienced in the energy and mining sectors despite the current use of tough and hard coatings. During the coating process significant tensile residual stresses may build up and result in premature failure of a component. These tensile stresses can be reduced by adopting functionally graded structures of the composite. The main goal of the present study is to design an ideal material gradient in the additively manufactured composite using the plasma transferred arc (PTA) with a WC-Ni alloy graded in WC. To develop a comprehensive analysis of the functionally graded deposit, the thermal history of the WC and Ni alloy powders are first simulated as they travel through the plasma and deposit on the substrate. The initial temperature of each deposited bead depending on the WC content is deduced. These results are used as an input to predict the temperature and stress history of the solidifying deposit. Thermal stresses are computed and trends of residual stresses are obtained as a function of the WC gradient selected. The trends obtained are compared quantitatively before concluding on the most favorable gradient for this wear resistance application.
Effect of powder properties on mesoscale thermal FEM simulations of powder bed additive manufacturing
Authors: Upadhyay Meet , Sinclair Chad , Maijer Daan
Published: May 2023

Numerous studies have used FEM simulations to assess the effects of the heat source parameters on the melt pool volume during metal powder bed additive manufacturing. However, considerable debate still exists on how to incorporate the evolution of the thermophysical properties used to describe the powder as it undergoes heating, melting, consolidation and finally solidification. For single layer studies, since powder volume is much smaller compared to the substrate volume, highly detailed, computationally expensive powder property descriptions may not provide a commensurate increase in accuracy of simulation results. This study aims to quantify the effect of powder properties on the melt pool volume created during electron beam melting of Ti6Al4V powder using predictions from a FEM-based heat conduction model. The dependence of thermal conductivity, specific heat, and density of the powder on temperature and beam power density will be studied. Additionally, the relevance of the powder properties with changing layer height and beam power and speed will also be quantified.
Toward semantic standard and process ontology for Additive manufacturing
Authors: Gouttebroze S , Friis J , Hovig E W , Boivie K
Published: May 2023

Advanced modelling of additive manufacturing often requires the combination of models at multiple scales and multi-physics. Therefore, building the modelling workflow describing the process is complicated. The modelling is also only a part of the innovation process and must be connected to practices, experimental work, and characterisation. Efficient communication and data exchange between the different actors could quickly become a challenge. Recent developments in the frame of the EMMC (European Material Modelling Council) and in the EU project OntoTrans points toward the early integration of semantic description and the creation of dedicated domain ontologies. This require an unambiguous and consistent use of terms and definitions for various concepts within each field of technology, and international standards is an available source for structured technical terms and definitions. For additive manufacturing (AM) the international standard ISO/ASTM 52900 “Additive manufacturing - General principles - Fundamentals and vocabulary” is the internationally recognised source for terms and definitions. Basing the ontology on the AM terminology standard will greatly facilitate integration of AM processes as a part of an industrial manufacturing system. Therefore, the present work attempts to harmonise the standard terminology and the ontology concepts. Then, to improve the impact and connection to material science, the concepts will be connected to a microstructure domain ontology and to the top- and middle-level ontology EMMO. The conceptualisation and application of the ontologies will be illustrated through simple examples of process and material modelling.
Calculation of thermal features in welding and additive manufacturing
Authors: Mendez Patricio F.
Published: May 2023

This paper summarizes multiple engineering expressions that enable the prediction of thermal magnitudes of interest associated with moving heat sources. The expressions use only fundamental parameters available before performing any experiments, and their calculation is algebraic, without the need for numerical methods. All expressions are based on the fundamental governing equations of heat transfer in the solid. The magnitudes predicted include maximum width and its location, maximum penetration, thickness of HAZ, maximum temperature and its location, leading and trailing edge of an isotherm, heating and cooling rate, aspect ratio of an isotherm, melting efficiency, cooling time from 800°C to 500°C, solidification time, and maximum distribution of a heat source to reach a target temperature. Parameters involved include heat source power and speed, thermal conductivity and diffusivity of the substrate material, temperature of interest and preheat or interpass temperature. Temperature-dependent properties are accounted for by the use of effective properties. The expressions proposed can be extended into sophisticated geometries for welding and specific additive manufacturing cases.
Transient simulation of melt flow, clogging, and clog fragmentation inside SEN during steel continuous casting
Authors: Barati H , Wu M , Kharicha A , Ludiwg A
Published: May 2023

Clogging of submerged entry nozzle (SEN) during continuous casting of steel is an undesirable phenomenon leading to different problems like flow blockage, slag entrainment, nonuniform solidification, etc. A transient numerical model for nozzle clogging based on an Eulerian-Lagrangian approach was developed and it covers the main steps of clogging: (a) formation of the first oxide layer by chemical reactions on the steel-refractory interface; (b) motion of non-metallic inclusions (NMIs) due to the turbulent melt flow towards the SEN wall; (c) interactions between the melt, the NMI, and the wall; (d) formation and growth of the clog by the deposition of NMIs on the clog front and the flow-clog interactions; and (e) detachment/fragmentation of a part of clog due to the flow drag force. Clogging in an industrial scale SEN was simulated. The simulated clog front was compared with real as-clogged SENs. The modeling results have successfully explained the SEN clogging induced transient flow phenomenon in the mold region, i.e. the transition from the stable to an unstable and non-symmetrical flow.
Influence of the adjustable EMBr on the asymmetric flow in a thin slab caster with a misaligned SEN
Authors: Vakhrushev A , Karimi-Sibaki E , Wu M , Ludwig A , Nitzl G , Tang Y , Hackl G , Watzinger J , Kharicha A
Published: May 2023

The thin slab casting (TSC) of steel is a type of the continuous casting (CC) with a narrow funnel-shaped mold, characterized by the rapid solidification and fast production rates. A highly turbulent flow impacts on a growing solid shell due to the constant feeding of the fresh hot melt. That strongly affects the solidification profiles and final quality of the TSC slabs. The presented work numerically investigates the solidification inside the TSC mold with the asymmetric flow pattern caused by the misalignment (tilting) of the submerged entry nozzle (SEN). These effects were considered with and without the applied electromagnetic brake (EMBr). The influence of the adjustable EMBr on the asymmetric flow and solidification profiles including turbulent and magnetohydrodynamic (MHD) effects were studied. During consistent series of simulations, the EMBr was varied between the magnetic poles and the time-averaged velocity and temperature fields were collected. The results showed that symmetric EMBr of a local type could partially improve the asymmetry. An optimal braking scenario was found for the casing speed of 5.5 m/min and maximum EMBr value of 180 mT. The solidification and MHD models including turbulence were developed using OpenFOAM®.
Model of multiphase flow, superheat transport, and particle capture in a steel continuous caster
Authors: Liang Mingyi , Cho Seong-Mook , Ruan Xiaoming , Thomas Brian G
Published: May 2023

A model of turbulent multiphase flow, heat transfer, and particle entrapment during continuous casting of steel is presented. The model includes the top 7m of the vertical and curved strand, and considers the effects of argon gas injection and thermal buoyancy. RANS model flow results are compared with LES. Lagrangian particle transport through the Eulerian-Eulerian multiphase flow field from the k-ɛ RANS model is based on random walk and features advanced particle capture criteria, improved from previous work by including anisotropic turbulent velocity fluctuations near the walls. Particle capture via 3 mechanisms is included: capture by solidified hooks at the meniscus, entrapment between dendrites, and engulfment by surrounding large particles. The fluid flow and bubble/inclusion capture results are validated with plant measurements, including nail board dipping tests and ultrasonic tests of particle locations, and good agreement is seen. The superheat has negligible effect on flow in the mold region but causes complex flow in the lower strand by creating multiple recirculation zones due to the thermal buoyancy. With high (30 K) superheat, this leads to less penetration, and slightly fewer and shallower capture of particles. Lower (10 K) superheat may enable significant top surface freezing, leading to very large internal defect clusters. Lower superheat also leads to deeper meniscus hooks, and more surface capture. Capture bands occur near the transition from vertical to curved, where downward liquid flow velocity balances the particle terminal velocity.
Quantifying X-ray diffractometer precision for measurement of dislocation density and the evolution of defect structures during solidification of additive manufacturing powders
Authors: Azersky C , Jeon S , Settens C , Fakhrul M , Matson D
Published: May 2023

In this work, the Phillips PW 3020 X’Pert Diffractometer and PANalytical X’Pert Pro MPD X-ray Diffractometer were used to perform in-situ monitoring of quenched microstructures to define the defect evolution of Inconel 718 additive manufacturing powder. Dislocation density analysis based on X-ray Diffraction (XRD) measurement is sensitive to XRD peak broadening. The X-ray line profile is affected by the instrumental effects of the diffractometer, so quantifying and analyzing XRD instrument performance is important for accurate dislocation density analysis. The average measurement bias of the Phillips diffractometer was found to be -1.5490·10−3 Å while the precision was found to be 6.1000·10−5 Å. The average measurement bias of the PANalytical diffractometer was found to be -1.7633·10−4 Å while the precision was found to be 7.6917·10−5 Å. The average dislocation density calculated from the data was 3.93·1014 m−2 for the smaller particle size range and 2.58·1014 m−2 for the larger particle size range. The number of diffraction peaks utilized in dislocation density analysis was found to be a more significant factor than the instrumental differences. This work confirmed that differences in defect structure density can be observed across differently sized particles sourced from additive manufacturing powder.
Effects of instabilities on the properties of ingots made by the ESR and VAR processes
Authors: Hans S , Mitchell A
Published: May 2023

The ESR and VAR processes are very often carried out under less-than-ideal conditions where the procedure involves inadvertent instabilities such as interruptions in metal flow or abrupt changes in the process heat balance. In this work we demonstrate the effects of typical examples of such instability as related to the remelting processes. It is suggested that a major direction in modelling development should be towards an understanding of the extent to which instability can be tolerated relative to the product requirements. Such an understanding would assist in the establishment of suitable quality standards governing the production of high-quality alloys.
Modeling of oxide inclusions in steel casting
Authors: Donahue R , Hardin R , Beckermann C
Published: May 2023

A model is presented that predicts the amount and location of oxide inclusions in steel castings. A number and size distribution of inclusions, defined about a mean diameter, enters the casting system at its inlet during the filling process and are transported to their final locations in the casting. Model parameters for inclusion density, drag and wall friction are used to calculate the motion and locations of the oxide particles. Model results are presented to study the effects of casting shape and surface orientation on the final inclusion locations and distributions within castings. These results are compared with inclusion tracking experiments where the geometry of the gating system and orientation of casting cope surfaces affect the final distribution of inclusions in the castings. Measured and simulated inclusion area percent coverage, inclusion count and mean diameter are compared for a range of modelling parameters and inclusion size distributions. The size and number distribution at the casting system inlet, and other model parameters, are determined which provide the best agreement between measured and simulated inclusion area, count, and size.
Simulation of dendritic deformation induced by convection in alloy solidification
Authors: Yang Luwei , Ren Neng , Li Jun , Xia Mingxu , Dong Hongbiao , Li Jianguo
Published: May 2023

Dendritic deformation induced by convection of thermal fluid is one of the factors leading to dendrite fragmentation and plays a crucial role in grain structure of alloy, which lacks in-depth understanding. In this paper, we simulate the flow-induced mechanical deformation of dendrites during the solidification of Al-4.5wt.%Cu alloy by combining the cellular automaton-finite volume method (CA-FVM) for the dendrite growth and the finite element method (FEM) for handling the dendritic deformation with the complex boundary conditions given by CA-FVM results. It shows that the dendritic deformation strongly depends on the flow velocities of melt and dendritic morphology. The dendrites can undergo visible bending above the critical flow velocities for dendrite yield (ranging from 0.023 m/s to 0.126 m/s as the inlet velocity increases) and the von Mises stress increases as the flow is enhanced during the growth process.
On the occurrence of buoyancy-induced oscillatory growth instability in directional solidification of alloys
Authors: Barbera Josep Maria , Isensee Thomas , Tourret Damien
Published: May 2023

Recent solidification experiments identified an oscillatory growth instability during directional solidification of Ni-based superalloy CMSX4 under a given range of cooling rates. From a modeling perspective, the quantitative simulation of dendritic growth under convective conditions remains challenging, due to the multiple length scales involved. Using the dendritic needle network (DNN) model, coupled with an efficient Navier-Stokes solver, we reproduced the buoyancy-induced growth oscillations observed in CMSX4 directional solidification. These previous results have shown that, for a given alloy and temperature gradient, oscillations occur in a narrow range of cooling rates (or pulling velocity, V
p
) and that the selected primary dendrite arm spacing (Λ) plays a crucial role in the activation of the flow leading to oscillations. Here, we show that the oscillatory behavior may be generalized to other binary alloys within an appropriate range of (V
p
,Λ) by reproducing it for an Al-4at.%Cu alloy. We perform a mapping of oscillatory states as a function of V
p
and Λ, and identify the regions of occurrence of different behaviors (e.g., sustained or damped oscillations) and their effect on the oscillation characteristics. Our results suggest a minimum of V
p
for the occurrence of oscillations and confirm the correlation between the oscillation type (namely: damped, sustained, or noisy) with the ratio of average fluid velocity

V
¯

over V
p
. We describe the different observed growth regimes and highlight similarities and contrasts with our previous results for a CMSX4 alloy.
Diffuse modelling of pearlite growth in Calphad-coupled multicomponent multi-phase-field simulations
Authors: Eiken J , Böttger B , Apel M
Published: May 2023

During cooling of steels and cast irons, austenite can decompose by a eutectoid transformation into pearlite, a two-phased mixture of ferrite and cementite. Since the internal lamellar structure is commonly too fine to be distinguished on the scale of the austenite grain structure, pearlite is often modelled as an effective, pseudo-single phase. Such a pragmatic treatment would also be desirable to reduce the computational effort of large-scale multi-phase-field simulations, but a fundamental hindrance is that no consistent thermodynamic description exists for effective pearlite in multicomponent databases. Alternatively, we here propose to model pearlite as diffuse mixture of two phases with individual local fractions and concentrations, such that solute partitioning and thermodynamic driving forces can be consistently derived from standard Calphad databases. The essential computational advantage is that only the outer interfaces of the pearlite nodules have to be numerically resolved, which allows for increased grid spacing and time-steps. The impact of the unresolved lamellar structure on the curvature undercooling is modelled analytically based on a characteristic spacing, which may be calibrated either experimentally or by small-scale simulations. The potential and the limitations of the new approach, implemented in the frame of the Micress® software, shall be discussed.
Phase-field lattice Boltzmann simulation of three-dimensional settling dendrite with natural convection during nonisothermal solidification of binary alloy
Authors: Sakane S , Aoki T , Takaki T
Published: May 2023

Understanding the motion and growth behaviors of equiaxed dendrites during solidification is important for predicting macrosegregation. In this study, we develop a phase-field lattice Boltzmann (PF-LB) simulation method for the settling and growth of an equiaxed dendrite during the nonisothermal solidification of a binary alloy. The PF-LB computations are accelerated by employing parallel computation using multiple graphic processing units (GPUs) and the octree block-structured adaptive mesh refinement method, which incorporates multiple mesh and time increment methods. By using the developed method, we can simulate the three-dimensional long-distance settling dendrite while considering the effects of latent heat release and natural convection. From the simulation results, we confirm that the natural convection due to the high solute concentration around a dendrite reduces the settling velocity. In addition, we observe that the temperature increase owing to latent heat release slows dendrite growth, which in turn slightly slows the settling velocity. From these results, we confirm that the effects of latent heat release and natural convection are not negligible in the quantitative evaluation of settling dendrites.
Investigation of diffusive grain interactions during equiaxed dendritic solidification
Authors: Chirouf Abdelhalim , Appolaire Benoît , Finel Alphonse , Bouar Yann Le , Založnik Miha
Published: May 2023

Grain growth during the solidification of an alloy is accompanied by the enrichment of the surrounding liquid phase in chemical species. The resulting diffusion fields induce interactions between the grains that are strongly dependent on their spatial arrangement. The influence of these diffusive interactions is not limited to the shapes and sizes of grains but also controls the overall kinetics of the transformation. In this study we investigate the role of the spatial arrangement of equiaxed grains in the average growth kinetics of an ensemble of grains. We perform full-field simulations of different grain ensembles using the mesoscopic grain envelope model (GEM). We show that the growth kinetics of randomly arranged ensembles is fundamentally different from that of periodic arrangements. We provide an explanation of this difference through analyses of the behaviour of individual grains in their local neighbourhood, defined by a Voronoi tessellation. Finally, we compare the full-field GEM simulations to state-of-the-art mean-field models and we point out the limitations of the latter in the prediction of dendritic growth.
Phase field model of microstructure formation during cooling slope slurry generation of novel Al-15Mg2Si-4.5Si composite
Authors: Das Prosenjit
Published: May 2023

The present study discusses the development of a two-dimensional phase field model of semi solid microstructure evolution of the novel Al-15Mg2Si-4.5Si composite during cooling slope rheoprocessing. The superheated melt of the said composite undergoes partial solidification during its shear flow over the slope free surface, prior to get collected within the isothermal slurry holding furnace. Seed undercooling based nucleation model is adopted in the present PF model to simulate slurry microstructure of the composite. Experimentally determined cooling rate values are considered to simulate slurry microstructure for different process conditions. Micrographs of melt samples collected during experimentation establishes the developed PF model as an accurate microstructure prediction tool for the composite slurry. Apart from morphological features such as size and degree of sphericity values of the evolving primary Mg2Si and α-Al grains, the model predictions includes melt temperature as well as solid content at any given instant of slurry processing.
Reconstruction of dendritic growth by fast tomography and phase field filtering
Authors: Yasuda H , Nishiguchi A , Xue H , Nonomura M , Nakano K , Katsube R , Narumi T , Takaki T
Published: May 2023

Three dimensional models of dendritic structures during solidification are valuable for building physical models, validating simulated results, estimating some properties such as permeability in the mushy, simulating semisolid deformation and so on. Thus, it is of interest to observe microstructure evolution in situ. Time-resolved tomography combined with X-ray diffraction has allowed us to observe the evolution of dendritic structures and to measure crystallographic orientation in situ. Reconstruction still proves to be difficult for some alloy systems because of the tradeoff between time and spatial resolution. This paper demonstrates the reconstruction of dendritic structures for three different alloy systems (Al-10mass%Cu alloy with a diameter of 4 mm, CrMnFeCoNi alloy with 1 mm, and Zn-4mass%Al alloy with 0.7 mm). The observations were performed in a synchrotron radiation facility SPring-8. A filter using a phase field model was introduced to reconstruct the three-dimensional images. Parameters used in the filtering were consistently determined based on the raw reconstruction images. Evaluation of solid-liquid interface area and curvature was significantly improved by the filter. For the Al-Cu alloy, a three-dimensional model containing approximately 300 million voxels was obtained. For the CrMnFeCoNi alloys, the preferred growth direction <100> was confirmed by tomography and X-ray diffraction. For the Zn-Al alloy, the observed 14 growth directions were not simply defined by the crystallographic orientations, although the directions were consistent with the hexagonal symmetry. This study verifies that time resolved tomography, X-ray diffraction and the filter using a phase field model provide three dimensional models for light metal alloys with rather large diameters and 3d transition-metal alloys with rather large X-ray absorption coefficients. The models are expected to be used for further studies.
Impact of fin width on nano scale tri-gate FinFET including the quantum mechanical effect
Authors: Panchanan Suparna , Maity Reshmi , Baidya Achinta , Maity Niladri Pratap
Published: May 2023

An inversion charge-based threshold voltage model is proposed for 10 nm channel length Tri-gate (TG) FinFET. The variation threshold voltage has been studied with respect to fin width

W

f
i
n

for different fin height

H

f
i
n

and channel length

L

.

The effect of width quantization has been explained with the help of the quantum mechanical effect (QME). A precise comparison of threshold voltage in terms of classical mechanics and quantum mechanics depicts the presence of width quantization in short channel device. The improvement of the short channel effects (SCEs), like subthreshold swing (SS), drain-induced barrier lowering (DIBL) and threshold voltage roll off have been studied. The impact of channel length to fin width ratio on DIBL and

S
S

has been examined. The improvement of the SCEs at the same oxide thickness has been observed for high-k dielectric material. The potential and effect of hafnium oxide (HfO2) have been discussed and validated using technology computer-aided design (TCAD) simulation.