N. Bianco-Stein, I. Polishchuk, Arad Lang, G. Atiya, J. Villanova, P. Zaslansky, A. Katsman, B. Pokroy
Jania sp. is an articulated coralline red alga that is abundant in the shallow waters of oceans worldwide. We have previously demonstrated that its structure is highly intricate and exhibits hierarchical organization across multiple length scales from the macro to the nano scale. Moreover, we have proven that the inner pores of its structure are helical, conveying the alga greater compliance as compared to a cylindrical configuration. Herein, we reveal new insights on the structure of Jania sp., particularly on its crystallographic variations and the internal elemental distribution of Mg and Ca. We show that the high-Mg calcite cell wall nanocrystals of Jania sp. are arranged in layers with alternating Mg contents. Moreover, we show that this non-homogenous elemental distribution assists the alga in preventing fracture caused by crack propagation. We further discover that each one of the cell wall nanocrystals in Jania sp. is not a single crystal as was previously thought, but rather comprises Mg-rich calcite nanoparticles demonstrating various crystallographic orientations, arranged periodically within the layered structure. We also show that these Mg-rich nanoparticles are present in yet another species of the coralline red algae, Corallina sp., pointing to the generality of this phenomenon. To the best of our knowledge this is a first report on the existence of Mg-rich nanoparticles in the coralline red algae mineralized tissue. We envisage that our findings on the bio-strategy found in the alga to enhance the fracture toughness will have an impact on the design of structures with superior mechanical properties. Statement of Significance: Understanding the structure-property relation in biomineralized tissues is of great importance in unveiling Nature's material design strategies, which form the basis for the development of novel structural materials. Crystallographic and elemental variations in the skeletal parts of the coralline red algae and their cumulative contribution to prevention of mechanical failure are yet poorly studied. Herein, we reveal that the high-Mg calcite cell wall nanocrystals of Jania sp. are arranged in layers with alternating Mg concentrations and reveal that this organization facilitates crack deflection, thereby preventing catastrophic fracture. We further discovered that the nanocrystals contain incoherent Mg-rich nanoparticles and suggest that they form via spinodal decomposition of the Mg-ACC precursor and self-arrange periodically throughout the alga's mineralized cell wall, a phenomenon most likely to be widespread in high-Mg calcite biomineralization.
{"title":"Structural and Chemical Variations in the Skeletal Segments of Coralline Red Algae Lead to Improved Crack Resistance","authors":"N. Bianco-Stein, I. Polishchuk, Arad Lang, G. Atiya, J. Villanova, P. Zaslansky, A. Katsman, B. Pokroy","doi":"10.2139/ssrn.3790077","DOIUrl":"https://doi.org/10.2139/ssrn.3790077","url":null,"abstract":"Jania sp. is an articulated coralline red alga that is abundant in the shallow waters of oceans worldwide. We have previously demonstrated that its structure is highly intricate and exhibits hierarchical organization across multiple length scales from the macro to the nano scale. Moreover, we have proven that the inner pores of its structure are helical, conveying the alga greater compliance as compared to a cylindrical configuration. Herein, we reveal new insights on the structure of Jania sp., particularly on its crystallographic variations and the internal elemental distribution of Mg and Ca. We show that the high-Mg calcite cell wall nanocrystals of Jania sp. are arranged in layers with alternating Mg contents. Moreover, we show that this non-homogenous elemental distribution assists the alga in preventing fracture caused by crack propagation. We further discover that each one of the cell wall nanocrystals in Jania sp. is not a single crystal as was previously thought, but rather comprises Mg-rich calcite nanoparticles demonstrating various crystallographic orientations, arranged periodically within the layered structure. We also show that these Mg-rich nanoparticles are present in yet another species of the coralline red algae, Corallina sp., pointing to the generality of this phenomenon. To the best of our knowledge this is a first report on the existence of Mg-rich nanoparticles in the coralline red algae mineralized tissue. We envisage that our findings on the bio-strategy found in the alga to enhance the fracture toughness will have an impact on the design of structures with superior mechanical properties. Statement of Significance: Understanding the structure-property relation in biomineralized tissues is of great importance in unveiling Nature's material design strategies, which form the basis for the development of novel structural materials. Crystallographic and elemental variations in the skeletal parts of the coralline red algae and their cumulative contribution to prevention of mechanical failure are yet poorly studied. Herein, we reveal that the high-Mg calcite cell wall nanocrystals of Jania sp. are arranged in layers with alternating Mg concentrations and reveal that this organization facilitates crack deflection, thereby preventing catastrophic fracture. We further discovered that the nanocrystals contain incoherent Mg-rich nanoparticles and suggest that they form via spinodal decomposition of the Mg-ACC precursor and self-arrange periodically throughout the alga's mineralized cell wall, a phenomenon most likely to be widespread in high-Mg calcite biomineralization.","PeriodicalId":9858,"journal":{"name":"Chemical Engineering (Engineering) eJournal","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83648537","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract The demagnetization field distribution of a magnetized Nd-Fe-B magnet was calculated and analyzed quantitatively. Multilayered composite Nd-Fe-B magnets with specific coercivity gradient distributions lower than the demagnetization field gradient were designed and fabricated via diffusion bonding under pressure. The magnetic property dependence on the interlayer magnet thickness was studied. The low coercivity interlayer magnet with the thickness lower than the critical value does not decrease the overall magnetic properties obviously. Effective self-bonding was observed in the interface between adjacent Nd-Fe-B magnets. The crystal orientations of matrix grains and the interface phase compositions were further studied. Multilayered composite Nd-Fe-B magnets make full use of the demagnetization field distribution to save the heavy rare earth Dy/Tb sources. This work paves a new way to design and fabricate Nd-Fe-B magnets with high magnetic properties.
{"title":"A Novel Strategy to Design and Fabricate Nd-Fe-B Magnets","authors":"Fugang Chen, Tieqiao Zhang, Yong Zhao, Xiaoli Wang, Caiping Jiang, Jinlu Chen, Wenqiang Zhao","doi":"10.2139/ssrn.3708677","DOIUrl":"https://doi.org/10.2139/ssrn.3708677","url":null,"abstract":"Abstract The demagnetization field distribution of a magnetized Nd-Fe-B magnet was calculated and analyzed quantitatively. Multilayered composite Nd-Fe-B magnets with specific coercivity gradient distributions lower than the demagnetization field gradient were designed and fabricated via diffusion bonding under pressure. The magnetic property dependence on the interlayer magnet thickness was studied. The low coercivity interlayer magnet with the thickness lower than the critical value does not decrease the overall magnetic properties obviously. Effective self-bonding was observed in the interface between adjacent Nd-Fe-B magnets. The crystal orientations of matrix grains and the interface phase compositions were further studied. Multilayered composite Nd-Fe-B magnets make full use of the demagnetization field distribution to save the heavy rare earth Dy/Tb sources. This work paves a new way to design and fabricate Nd-Fe-B magnets with high magnetic properties.","PeriodicalId":9858,"journal":{"name":"Chemical Engineering (Engineering) eJournal","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82310579","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Harishchandra Singh, T. Alatarvas, A. Kistanov, Assa SasikalaDevi, Shubo Wang, B. Sarpi, Y. Niu, A. Zakharov, Frank M. F. de Groot, M. Huttula, W. Cao, T. Fabritius
Abstract Determining non-metallic inclusions (NMIs) are essential to engineer ultra-high-strength steel as they play decisive role on performance and critical to probe via conventional techniques. Herein, advanced Synchrotron X-ray absorption coupled with photoemission electron microscopy and first-principles calculations are employed to provide the structure, local bonding structure and electronic properties of several NMI model systems and their interaction mechanism within and the steel matrix. B K-, N K-, Ca L2,3- and Ti L2,3-edge spectra show that the additional B prefers to result in h-BN exhibiting strong interaction with Ca2+. Such Ca2+-based phases also stabilize through TiN, revealing the irregular coordination of Ca2+. Observed intriguing no interaction between TiN and BN is further supported with the first-principles calculations, wherein unfavorable combination of TiN and h-BN and stabilization of bigger sized Ca2+-based inclusions have been found. These observations can help to optimize the interaction mechanism among various inclusions as well as steel matrix.
非金属夹杂物(nmi)的测定对超高强度钢的性能起着决定性的作用，对常规技术的探测至关重要，因此对超高强度钢的设计至关重要。本文采用先进的同步加速器x射线吸收技术，结合光电显微镜和第一性原理计算，提供了几种NMI模型体系的结构、局部键结结构和电子性质，以及它们在钢基体内部的相互作用机制。B - K-， N - K-， Ca - L2,3-和Ti - L2,3边光谱表明，额外的B倾向于导致h-BN与Ca2+表现出强相互作用。这种Ca2+基相也通过TiN稳定，揭示了Ca2+的不规则配位。观察到TiN和BN之间没有相互作用，这进一步得到第一性原理计算的支持，其中TiN和h-BN的不利组合和更大尺寸的Ca2+基包体的稳定被发现。这些观察结果有助于优化各种夹杂物和钢基体之间的相互作用机制。
{"title":"Unveiling Interactions of Non-Metallic Inclusions within Advanced Ultra-High Strength Steel: A Spectro-Microscopic Determination and First-Principles Elucidation","authors":"Harishchandra Singh, T. Alatarvas, A. Kistanov, Assa SasikalaDevi, Shubo Wang, B. Sarpi, Y. Niu, A. Zakharov, Frank M. F. de Groot, M. Huttula, W. Cao, T. Fabritius","doi":"10.2139/ssrn.3757898","DOIUrl":"https://doi.org/10.2139/ssrn.3757898","url":null,"abstract":"Abstract Determining non-metallic inclusions (NMIs) are essential to engineer ultra-high-strength steel as they play decisive role on performance and critical to probe via conventional techniques. Herein, advanced Synchrotron X-ray absorption coupled with photoemission electron microscopy and first-principles calculations are employed to provide the structure, local bonding structure and electronic properties of several NMI model systems and their interaction mechanism within and the steel matrix. B K-, N K-, Ca L2,3- and Ti L2,3-edge spectra show that the additional B prefers to result in h-BN exhibiting strong interaction with Ca2+. Such Ca2+-based phases also stabilize through TiN, revealing the irregular coordination of Ca2+. Observed intriguing no interaction between TiN and BN is further supported with the first-principles calculations, wherein unfavorable combination of TiN and h-BN and stabilization of bigger sized Ca2+-based inclusions have been found. These observations can help to optimize the interaction mechanism among various inclusions as well as steel matrix.","PeriodicalId":9858,"journal":{"name":"Chemical Engineering (Engineering) eJournal","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78242337","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
V. Wang, Jun-ping Du, H. Somekawa, S. Ogata, W. Geng
Segregation of rare earth alloying elements are known to segregate to grain boundaries in Mg and suppress grain boundary sliding via strong chemical bonds. Segregation of Mn, however, has recently been found to enhance grain boundary sliding in Mg and thereby boosting its ductility. Taking the Mg (-2114) twin boundary as an example, we have performed a first-principles comparative study on the segregation and chemical bonding of Y, Zn, and Mn at this boundary. We find that both Y-4d and Mn-3d states hybridize with the Mg-3sp states, while Zn-Mg bonding is characterized by charge transfer only. Strong spin-polarization of Mn pushes the up-spin 3d states down, leading to less anisotropic Mn-Mg bonds with more delocalized charge distribution at the twin boundary, and thus promotes grain boundary plasticity, e.g., grain boundary sliding.
{"title":"Spin Polarization of Mn Enhances Grain Boundary Sliding in Mg","authors":"V. Wang, Jun-ping Du, H. Somekawa, S. Ogata, W. Geng","doi":"10.2139/ssrn.3820201","DOIUrl":"https://doi.org/10.2139/ssrn.3820201","url":null,"abstract":"Segregation of rare earth alloying elements are known to segregate to grain boundaries in Mg and suppress grain boundary sliding via strong chemical bonds. Segregation of Mn, however, has recently been found to enhance grain boundary sliding in Mg and thereby boosting its ductility. Taking the Mg (-2114) twin boundary as an example, we have performed a first-principles comparative study on the segregation and chemical bonding of Y, Zn, and Mn at this boundary. We find that both Y-4d and Mn-3d states hybridize with the Mg-3sp states, while Zn-Mg bonding is characterized by charge transfer only. Strong spin-polarization of Mn pushes the up-spin 3d states down, leading to less anisotropic Mn-Mg bonds with more delocalized charge distribution at the twin boundary, and thus promotes grain boundary plasticity, e.g., grain boundary sliding.","PeriodicalId":9858,"journal":{"name":"Chemical Engineering (Engineering) eJournal","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-04-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75292860","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
We report on the formation of a critical ferroelectric state induced by the He+ ion implantation in potassium tantalate niobate crystal. An obvious phase change has been observed in the ion irradiated region, which is mostly related to the stable polarized nanometric regions formed during the ion implantation process. Under the irradiation of 2 MeV He+ ions, two distinguishable layers corresponding to different energy transfer modes (elastic nuclear collision and inelastic electronic collision, respectively) between the incident He + ions and the intrinsic lattices have been formed beneath the irradiated surface. Lattice dynamics before and after the ion implantation process are investigated by a confocal μ-Raman system. And the variations of typical Raman-active vibrational modes demonstrate the presence of lattice distortion in the irradiated region. X-ray diffraction experiments further suggest the uniform lattice elongation in this region. Piezo-response force characteristic measurements reveal the existence of stable polarized nanometric regions with more intense polarization and verify that the crystal with such a phase status possesses extraordinary microscopic disorders, which is different from the traditional ferroelectric or paraelectric phase. The ion implantation method provides a new approach to form a temperature-stable critical ferroelectric state in relaxor ferroelectric materials. Also, analyses of the modification on the lattice dynamics of the irradiated region can help us build a clear awareness of the physical essence of this critical state and the relaxor ferroelectricity.
{"title":"Obvious Phase Transition Status Induced by He +-Ions Implantation in KTN Crystal","authors":"Quanxin Yang, Xiaojin Li, Hongliang Liu, Dahuai Zheng, S. Akhmadaliev, Shengqiang Zhou, Pengfei Wu","doi":"10.2139/ssrn.3817904","DOIUrl":"https://doi.org/10.2139/ssrn.3817904","url":null,"abstract":"We report on the formation of a critical ferroelectric state induced by the He+ ion implantation in potassium tantalate niobate crystal. An obvious phase change has been observed in the ion irradiated region, which is mostly related to the stable polarized nanometric regions formed during the ion implantation process. Under the irradiation of 2 MeV He+ ions, two distinguishable layers corresponding to different energy transfer modes (elastic nuclear collision and inelastic electronic collision, respectively) between the incident He + ions and the intrinsic lattices have been formed beneath the irradiated surface. Lattice dynamics before and after the ion implantation process are investigated by a confocal μ-Raman system. And the variations of typical Raman-active vibrational modes demonstrate the presence of lattice distortion in the irradiated region. X-ray diffraction experiments further suggest the uniform lattice elongation in this region. Piezo-response force characteristic measurements reveal the existence of stable polarized nanometric regions with more intense polarization and verify that the crystal with such a phase status possesses extraordinary microscopic disorders, which is different from the traditional ferroelectric or paraelectric phase. The ion implantation method provides a new approach to form a temperature-stable critical ferroelectric state in relaxor ferroelectric materials. Also, analyses of the modification on the lattice dynamics of the irradiated region can help us build a clear awareness of the physical essence of this critical state and the relaxor ferroelectricity.","PeriodicalId":9858,"journal":{"name":"Chemical Engineering (Engineering) eJournal","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83609567","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
S. Bisso, C. Weber, V. Berger, N. Paunović, Y. Bao, Zhi Luo, J. Leroux
Photopolymerization-based 3D printing is now a well-established manufacturing technique for a wide range of applications, as it allows the customized fabrication of objects with high resolution, tunable mechanical properties, and various functionalities. However, after printing, the crosslinked polymeric networks cannot be easily degraded and recycled, raising economic and environmental concerns. To date, only a few reprocessable or partially recyclable 3D printing resins have been reported. These resins are based on complex formulations or specific chemical structures. In addition to their high production costs and their limited scope of applicability, none of these materials can be completely depolymerized after photopolymerization 3D printing. Here, a general strategy is proposed to design degradable and recyclable photopolymers for 3D printing by taking advantage of the reversible aza-Michael addition reaction. With this approach, complete degradation of printed objects can be achieved under ambient conditions with tunable kinetics. The depolymerized products can be recycled and directly used for re-printing without the need of adding extra resins. Furthermore, using dopamine as a representative monomer, the possibility of incorporating additional chemical functions into the printed materials, such as adhesive properties, is demonstrated.
{"title":"3D Printing of Recyclable Elastomers with Controllable Degradation and Adhesive Properties","authors":"S. Bisso, C. Weber, V. Berger, N. Paunović, Y. Bao, Zhi Luo, J. Leroux","doi":"10.2139/ssrn.3816000","DOIUrl":"https://doi.org/10.2139/ssrn.3816000","url":null,"abstract":"Photopolymerization-based 3D printing is now a well-established manufacturing technique for a wide range of applications, as it allows the customized fabrication of objects with high resolution, tunable mechanical properties, and various functionalities. However, after printing, the crosslinked polymeric networks cannot be easily degraded and recycled, raising economic and environmental concerns. To date, only a few reprocessable or partially recyclable 3D printing resins have been reported. These resins are based on complex formulations or specific chemical structures. In addition to their high production costs and their limited scope of applicability, none of these materials can be completely depolymerized after photopolymerization 3D printing. Here, a general strategy is proposed to design degradable and recyclable photopolymers for 3D printing by taking advantage of the reversible aza-Michael addition reaction. With this approach, complete degradation of printed objects can be achieved under ambient conditions with tunable kinetics. The depolymerized products can be recycled and directly used for re-printing without the need of adding extra resins. Furthermore, using dopamine as a representative monomer, the possibility of incorporating additional chemical functions into the printed materials, such as adhesive properties, is demonstrated.","PeriodicalId":9858,"journal":{"name":"Chemical Engineering (Engineering) eJournal","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-03-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80972667","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-03-29DOI: 10.21303/2461-4262.2021.001694
L. Frolova, Roman Shevchenko, Alona Shpyh, Vadim Khoroshailo, Yana Antonenko
In this work, the optimal combinations of Al – Si in cast iron for cast parts for machine-building purposes were determined with the aim of subsequent selection of rational modes of modification and alloying, and the possibility of their implementation under industrial smelting conditions was checked. The graphical dependence Si=f (Al) is obtained, which is a set of optimal combinations of the content of Al and Si in cast iron, providing the maximum ultimate tensile strength UTS≈245 ... 334 MPa. The technological audit of the results of serial industrial smelting included the analysis of actual indicators, the calculation of sample distribution functions (mathematical expectation and dispersion) of the Al and Si content in the alloy, as well as the UTS value. The correspondence of the indicators of the content of Al and Si and the value of σ to the optimal values was assessed by testing the statistical hypotheses: H: M(Al)=Alopt, M(Si)=Siopt, M(σв)=σвopt.On the basis of the obtained results of the assessment of statistical characteristics and verification of hypotheses, it was established that at the chosen significance level α=0.05, the technological process of smelting satisfies the requirements of optimality in terms of the Si content, but in terms of the Al content, the technological process does not meet the requirements of optimality. The proposed procedure for choosing the optimal combinations of Al and Si makes it possible to choose the amount of correcting additives depending on the actual indicators of the chemical composition during the smelting process. To do this, it is necessary to assess the closeness of the actual composition to the optimal curve Si=f(Al) and choose the one that most satisfies the criteria of rationality. The latter can be the cost of ferroalloys, through which Al and Si are introduced.
{"title":"Selection of Optimal Al–Si Combinations in Cast Iron for Castings for Engineering Purposes","authors":"L. Frolova, Roman Shevchenko, Alona Shpyh, Vadim Khoroshailo, Yana Antonenko","doi":"10.21303/2461-4262.2021.001694","DOIUrl":"https://doi.org/10.21303/2461-4262.2021.001694","url":null,"abstract":"In this work, the optimal combinations of Al – Si in cast iron for cast parts for machine-building purposes were determined with the aim of subsequent selection of rational modes of modification and alloying, and the possibility of their implementation under industrial smelting conditions was checked. \u0000 \u0000The graphical dependence Si=f (Al) is obtained, which is a set of optimal combinations of the content of Al and Si in cast iron, providing the maximum ultimate tensile strength UTS≈245 ... 334 MPa. \u0000 \u0000The technological audit of the results of serial industrial smelting included the analysis of actual indicators, the calculation of sample distribution functions (mathematical expectation and dispersion) of the Al and Si content in the alloy, as well as the UTS value. The correspondence of the indicators of the content of Al and Si and the value of σ to the optimal values was assessed by testing the statistical hypotheses: H: M(Al)=Alopt, M(Si)=Siopt, M(σв)=σвopt.On the basis of the obtained results of the assessment of statistical characteristics and verification of hypotheses, it was established that at the chosen significance level α=0.05, the technological process of smelting satisfies the requirements of optimality in terms of the Si content, but in terms of the Al content, the technological process does not meet the requirements of optimality. \u0000 \u0000The proposed procedure for choosing the optimal combinations of Al and Si makes it possible to choose the amount of correcting additives depending on the actual indicators of the chemical composition during the smelting process. To do this, it is necessary to assess the closeness of the actual composition to the optimal curve Si=f(Al) and choose the one that most satisfies the criteria of rationality. The latter can be the cost of ferroalloys, through which Al and Si are introduced.","PeriodicalId":9858,"journal":{"name":"Chemical Engineering (Engineering) eJournal","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-03-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82082042","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract Active room temperature solute induced diffusion-less climb of the edge dislocations in model Mg-Al alloys was observed using molecular dynamics simulations. Dislocations on prismatic and pyramidal I planes climb through the basal plane to overcome solute obstacles. This out-of-plane dislocation motion softens the high resistance pyramidal I glide and significantly reduces the anisotropy of dislocation mobility, and could help improve the ductility of Mg. The flow stress scales linearly with solute concentration, cAl. Dislocations climb predominantly in the negative direction, with climb angle on the order of 0.01cAl, producing very high vacancy concentration on the order of 10−4. This climb behavior was rationalized using an energy analysis by comparing the in-plane and out-of-plane motions between different Mg slip planes. The ease of climb depends on the strength of the solute-dislocation interaction and the compactness of the dislocation core.
{"title":"Solute Softening and Vacancy Generation by Diffusion-Less Dislocation Climb in Magnesium Alloys","authors":"P. Yi","doi":"10.2139/ssrn.3694095","DOIUrl":"https://doi.org/10.2139/ssrn.3694095","url":null,"abstract":"Abstract Active room temperature solute induced diffusion-less climb of the edge dislocations in model Mg-Al alloys was observed using molecular dynamics simulations. Dislocations on prismatic and pyramidal I planes climb through the basal plane to overcome solute obstacles. This out-of-plane dislocation motion softens the high resistance pyramidal I glide and significantly reduces the anisotropy of dislocation mobility, and could help improve the ductility of Mg. The flow stress scales linearly with solute concentration, cAl. Dislocations climb predominantly in the negative direction, with climb angle on the order of 0.01cAl, producing very high vacancy concentration on the order of 10−4. This climb behavior was rationalized using an energy analysis by comparing the in-plane and out-of-plane motions between different Mg slip planes. The ease of climb depends on the strength of the solute-dislocation interaction and the compactness of the dislocation core.","PeriodicalId":9858,"journal":{"name":"Chemical Engineering (Engineering) eJournal","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84264778","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Evan J. Musterman, D. Savytskii, V. Dierolf, H. Jain
Abstract Laser heating can be used to produce single crystal architectures in glass with a lattice that rotates at a constant rate. Such metamaterials can offer properties that are disallowed by conventional crystal structures. To establish the mechanism of this lattice rotation, we used transmission electron microscopy (TEM) to directly observe and characterize dislocations in Sb2S3 crystal lines fabricated in Sb-S-I glass as a model system. The lattice rotation calculated from the density and Burgers vectors of edge dislocations agrees with lattice rotation values experimentally determined by electron backscatter diffraction (EBSD) and selected area diffraction patterns (SADP). These results provide the first direct proof of the dislocation mechanism of lattice rotation in rotating lattice single (RLS) crystals, and very likely other forms of growth actuated bending, twisting and noncrystallographic branching as seen in spherulites.
{"title":"The Source of Lattice Rotation in Rotating Lattice Single (RLS) Crystals","authors":"Evan J. Musterman, D. Savytskii, V. Dierolf, H. Jain","doi":"10.2139/ssrn.3688747","DOIUrl":"https://doi.org/10.2139/ssrn.3688747","url":null,"abstract":"Abstract Laser heating can be used to produce single crystal architectures in glass with a lattice that rotates at a constant rate. Such metamaterials can offer properties that are disallowed by conventional crystal structures. To establish the mechanism of this lattice rotation, we used transmission electron microscopy (TEM) to directly observe and characterize dislocations in Sb2S3 crystal lines fabricated in Sb-S-I glass as a model system. The lattice rotation calculated from the density and Burgers vectors of edge dislocations agrees with lattice rotation values experimentally determined by electron backscatter diffraction (EBSD) and selected area diffraction patterns (SADP). These results provide the first direct proof of the dislocation mechanism of lattice rotation in rotating lattice single (RLS) crystals, and very likely other forms of growth actuated bending, twisting and noncrystallographic branching as seen in spherulites.","PeriodicalId":9858,"journal":{"name":"Chemical Engineering (Engineering) eJournal","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82810695","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract Selective Laser Sintering (SLS) is one of the advanced additive manufacturing technologies which can build the geometrically complex structure from a three-dimensional CAD model. Poly ether ether ketone (PEEK) is one of the available materials for SLS and has received numerous interesting due to its excellent properties. In this research, a novel approach, thermally induced phase separation (TIPS) was employed to produce neat PEEK and PEEK/CNT composite powders with near spherical shape, desired particle size and size distribution for SLS application. Powders produced by TIPS demonstrated good flowability and processability. SEM images proved that CNT was embedded in PEEK powder. PEEK/CNT composite powder had shown an increased crystallinity in comparison with neat PEEK powder. Sintering rate of produced powders were studied with hot stage microscopy. Single layer films were built successfully by high temperature selective laser sintering (HT-SLS) using the powder developed via TIPS. Thermodynamics characteristics of single layer films were studied by DMA. Results revealed that addition of 0.1% CNT improved both storage and loss modulus of PEEK.
{"title":"Poly Ether Ether Ketone and its Composite Powder Prepared by Thermally Induced Phase Separation for High Temperature Selective Laser Sintering","authors":"Yuan-Fan Wang, Jiawei Shen, Mengxue Yan, X. Tian","doi":"10.2139/ssrn.3805239","DOIUrl":"https://doi.org/10.2139/ssrn.3805239","url":null,"abstract":"Abstract Selective Laser Sintering (SLS) is one of the advanced additive manufacturing technologies which can build the geometrically complex structure from a three-dimensional CAD model. Poly ether ether ketone (PEEK) is one of the available materials for SLS and has received numerous interesting due to its excellent properties. In this research, a novel approach, thermally induced phase separation (TIPS) was employed to produce neat PEEK and PEEK/CNT composite powders with near spherical shape, desired particle size and size distribution for SLS application. Powders produced by TIPS demonstrated good flowability and processability. SEM images proved that CNT was embedded in PEEK powder. PEEK/CNT composite powder had shown an increased crystallinity in comparison with neat PEEK powder. Sintering rate of produced powders were studied with hot stage microscopy. Single layer films were built successfully by high temperature selective laser sintering (HT-SLS) using the powder developed via TIPS. Thermodynamics characteristics of single layer films were studied by DMA. Results revealed that addition of 0.1% CNT improved both storage and loss modulus of PEEK.","PeriodicalId":9858,"journal":{"name":"Chemical Engineering (Engineering) eJournal","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78990475","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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