S. Yu, T.T. Li, Y. Hu, W.S. Wang, C.X. Wang, T. Wang, L.J. Bai, G. Zhang
Most nanoscale metallic multilayers (NMMs) exhibit ultra-high hardness but limited toughness. To toughen Ti/Mo NMMs, a gradient multilayered (GM) structure was architected via manipulating individual layer thickness (h) gradient distribution along the film growth direction. The resulting GM structure significantly raises the toughness of Ti/Mo NMMs without reducing their peak hardness. High back stress developed from the plastic incompatibilities stemmed from aggravated microstructural heterogeneity is primarily responsible for the unprecedented synergy of hardness and toughness. Our findings provide a promising approach to concurrently strengthen and toughen NMMs.
{"title":"Architecting a Gradient Multilayered Structure to Concurrently Strengthen and Toughen Ti/Mo Nanoscale Multilayers","authors":"S. Yu, T.T. Li, Y. Hu, W.S. Wang, C.X. Wang, T. Wang, L.J. Bai, G. Zhang","doi":"10.2139/ssrn.3566587","DOIUrl":"https://doi.org/10.2139/ssrn.3566587","url":null,"abstract":"Most nanoscale metallic multilayers (NMMs) exhibit ultra-high hardness but limited toughness. To toughen Ti/Mo NMMs, a gradient multilayered (GM) structure was architected via manipulating individual layer thickness (h) gradient distribution along the film growth direction. The resulting GM structure significantly raises the toughness of Ti/Mo NMMs without reducing their peak hardness. High back stress developed from the plastic incompatibilities stemmed from aggravated microstructural heterogeneity is primarily responsible for the unprecedented synergy of hardness and toughness. Our findings provide a promising approach to concurrently strengthen and toughen NMMs.","PeriodicalId":18341,"journal":{"name":"Materials Science eJournal","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-04-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77902724","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}
J. Raval, Kailas Patole, Sakina Kachwala, Aarjav Sanghvi, Umesh R. Shinde
Bismuth Nickel iron(III) oxide (Bi 1-x Ni x FeO 3 ) is a multiferroic substance that has unique characteristic property of high antiferromagnetism & ferroelectricity. Pure Bi 1-x Ni x FeO 3 is obtained by calcining the semi synthesized(porous) product at 700°C. The report explains preparation of pure Bi 1-x Ni x FeO 3 using a cost effective, continuous stirring (combustion) method along with calcination. Molar ratio of Bi/Ni is varied as for the values of x=0.1,0.2,0.3,0.4. The results indicates formation of pure Bi 1-x Ni x FeO 3 product in the porous sol-gel form firstly and then powdered form finally after calcination for all values of 'x' ratio of Bi/Ni.
铋镍铁(III)氧化物(Bi 1-x Ni x FeO 3)是一种具有高反铁磁性和铁电性的多铁性物质。在700℃下煅烧半合成(多孔)产物，得到了纯净的bi1 -x Ni x feo3。该报告解释了使用经济有效的连续搅拌(燃烧)方法以及煅烧制备纯bi1 -x Ni x feo3的方法。当x=0.1、0.2、0.3、0.4时，Bi/Ni的摩尔比发生变化。结果表明:在不同Bi/Ni比值下，煅烧后先以多孔溶胶-凝胶形式生成纯Bi 1-x Ni x feo3，最后以粉末形式生成。
{"title":"Study of Structural and Magnetic Properties of Bi 1-xNi x FeO 3","authors":"J. Raval, Kailas Patole, Sakina Kachwala, Aarjav Sanghvi, Umesh R. Shinde","doi":"10.2139/ssrn.3575685","DOIUrl":"https://doi.org/10.2139/ssrn.3575685","url":null,"abstract":"Bismuth Nickel iron(III) oxide (Bi 1-x Ni x FeO 3 ) is a multiferroic substance that has unique characteristic property of high antiferromagnetism & ferroelectricity. Pure Bi 1-x Ni x FeO 3 is obtained by calcining the semi synthesized(porous) product at 700°C. The report explains preparation of pure Bi 1-x Ni x FeO 3 using a cost effective, continuous stirring (combustion) method along with calcination. Molar ratio of Bi/Ni is varied as for the values of x=0.1,0.2,0.3,0.4. The results indicates formation of pure Bi 1-x Ni x FeO 3 product in the porous sol-gel form firstly and then powdered form finally after calcination for all values of 'x' ratio of Bi/Ni.","PeriodicalId":18341,"journal":{"name":"Materials Science eJournal","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-04-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87813485","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}
The substitutional solute atom induced local lattice distortion (LLD) in dilute metal solid solution was believed to be uniform that may even be modeled by using soap bubble raft. Contrary to this conventional picture, we report in this manuscript that the Mo induced LLD in dilute Ti-Mo solid solution is highly non-uniform as evidenced by our first principles calculations. The non-uniform LLD is ascribed to the Jahn-Teller splitting of the degenerated d states of Mo atom. We propose that the substitutional solid solutions with non-uniform LLD should satisfy two conditions. With which, the solid-solutions suffering from non-uniform LLD are predicted. The non-uniform LLD is expected to result in non-spherical stress field around the solute atom, and, therefore, challenges the application of classical solid solution hardening model to this kind of solid solutions.
{"title":"Unconventional Non-Uniform Local Lattice Distortion in Dilute Ti-Mo Solid Solution","authors":"Q. Hu, Rui Yang","doi":"10.2139/ssrn.3604737","DOIUrl":"https://doi.org/10.2139/ssrn.3604737","url":null,"abstract":"The substitutional solute atom induced local lattice distortion (LLD) in dilute metal solid solution was believed to be uniform that may even be modeled by using soap bubble raft. Contrary to this conventional picture, we report in this manuscript that the Mo induced LLD in dilute Ti-Mo solid solution is highly non-uniform as evidenced by our first principles calculations. The non-uniform LLD is ascribed to the Jahn-Teller splitting of the degenerated d states of Mo atom. We propose that the substitutional solid solutions with non-uniform LLD should satisfy two conditions. With which, the solid-solutions suffering from non-uniform LLD are predicted. The non-uniform LLD is expected to result in non-spherical stress field around the solute atom, and, therefore, challenges the application of classical solid solution hardening model to this kind of solid solutions.","PeriodicalId":18341,"journal":{"name":"Materials Science eJournal","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-03-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89702941","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 : 2020-03-05DOI: 10.15587/2312-8372.2020.200628
V. Savenko, Sergii Illiash, T. Stasiuk
The object of research is the technology of hot asphalt concrete regeneration by the in-place method. Temperature regimes for heating asphalt concrete pavement are one of the key technological parameters that affect the quality of the output regenerated asphalt concrete. In order to establish the dependence of the temperature of the pavement heating at different depths on the heating time, field studies are carried out directly when performing work on the hot regeneration of asphalt concrete using the Reshape method. The work is carried out at an ambient temperature of 25–30 °C and calm weather. The regenerated hot asphalt mix, which is used when conducting studies on the grain composition and bitumen content, corresponded to a hot, fine-grained mixture, dense asphalt concrete, type A, continuous granulometry, grade II, in accordance with DSTU B V.2.7-119:2011. Content of residual bitumen loosened asphalt crumb is 6.0 %. During the research, measurements are carried out at different speeds (1.8 m/min and 2.1 m/min) of the thermal installation for heating the Wirtgen HM 4500 asphalt concrete pavement (country of origin is Germany). The obtained graphical dependencies and mathematical models make it possible to determine that the most optimal pavement heating mode is gradual heating. This mode will allow avoiding the burning of bitumen and provide pavement heating at the level of the base of the regenerated layer, which is very important when determining the temperature of mixing the mixture. Analysis of graphs and mathematical models suggests that a decrease in the temperature of the pavement heating by at least 10–20 °C will lead to an increase in the performance of the thermal device. In this case, the increase in productivity can be from 20 % to 25 %, which will reduce the gas consumption and, accordingly, the cost of work. Thus, the obtained dependencies can be used to optimize the process of hot asphalt concrete regeneration by the in-place method.
本文的研究对象是热沥青混凝土就地再生技术。沥青混凝土路面加热温度制度是影响产出再生沥青混凝土质量的关键技术参数之一。为了建立不同深度路面加热温度对加热时间的依赖关系，在对沥青混凝土进行重塑法热再生工作时，直接进行了现场研究。工作环境温度为25-30°C，天气平静。再生热沥青混合料在进行颗粒组成和沥青含量研究时使用，对应于热的细粒混合料，致密沥青混凝土，a型，连续粒度，II级，符合DSTU B V.2.7-119:2011。松散沥青屑残余沥青含量为6.0%。在研究过程中，以不同的速度(1.8 m/min和2.1 m/min)对加热Wirtgen HM 4500沥青混凝土路面的热装置进行了测量(原产国为德国)。得到的图形依赖关系和数学模型可以确定最优的路面加热方式是渐进加热。这种模式可以避免燃烧沥青，并在再生层的基层提供路面加热，这在确定混合料的温度时非常重要。图形和数学模型分析表明，路面加热温度降低至少10-20°C将导致热装置性能的提高。在这种情况下，生产率可以提高20%到25%，这将减少天然气消耗，从而降低工作成本。由此得出的相关关系可用于就地法优化热沥青混凝土再生工艺。
{"title":"Research of Temperature Change of Pavement Heating in the Process of Hot In-Place Recycling of Asphalt Concrete","authors":"V. Savenko, Sergii Illiash, T. Stasiuk","doi":"10.15587/2312-8372.2020.200628","DOIUrl":"https://doi.org/10.15587/2312-8372.2020.200628","url":null,"abstract":"The object of research is the technology of hot asphalt concrete regeneration by the in-place method. Temperature regimes for heating asphalt concrete pavement are one of the key technological parameters that affect the quality of the output regenerated asphalt concrete. In order to establish the dependence of the temperature of the pavement heating at different depths on the heating time, field studies are carried out directly when performing work on the hot regeneration of asphalt concrete using the Reshape method. The work is carried out at an ambient temperature of 25–30 °C and calm weather. The regenerated hot asphalt mix, which is used when conducting studies on the grain composition and bitumen content, corresponded to a hot, fine-grained mixture, dense asphalt concrete, type A, continuous granulometry, grade II, in accordance with DSTU B V.2.7-119:2011. Content of residual bitumen loosened asphalt crumb is 6.0 %. During the research, measurements are carried out at different speeds (1.8 m/min and 2.1 m/min) of the thermal installation for heating the Wirtgen HM 4500 asphalt concrete pavement (country of origin is Germany). The obtained graphical dependencies and mathematical models make it possible to determine that the most optimal pavement heating mode is gradual heating. This mode will allow avoiding the burning of bitumen and provide pavement heating at the level of the base of the regenerated layer, which is very important when determining the temperature of mixing the mixture. Analysis of graphs and mathematical models suggests that a decrease in the temperature of the pavement heating by at least 10–20 °C will lead to an increase in the performance of the thermal device. In this case, the increase in productivity can be from 20 % to 25 %, which will reduce the gas consumption and, accordingly, the cost of work. Thus, the obtained dependencies can be used to optimize the process of hot asphalt concrete regeneration by the in-place method.","PeriodicalId":18341,"journal":{"name":"Materials Science eJournal","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-03-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89877341","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}
The polyextremotolerant black yeast Exophiala dermatitidis is a tractable model system for investigation of adaptations under extreme conditions. Foremost amongst these adaptations is production of the defensive pigments melanins and carotenoids. A particularly important question is their metabolic production cost. However, this investigation has been hindered by a relatively poor systems-level understanding of E. dermatitidis metabolism. To address this challenge, a genome-scale model (iEde2091) was developed. Using iEde2091, carotenoids were found to be more expensive to produce than melanins. Given their overlapping protective functions, this suggests that carotenoids have an underexplored yet important role of photo-protection under high-energy visible light. Furthermore, multiple defensive pigments with overlapping functions might allow E. dermatitidis to minimize cost. Because iEde2091 revealed that E. dermatitidis synthesizes the same melanins as humans and the active sites of the key tyrosinase enzyme are highly conserved, this model may enable a broader understanding of melanin production across kingdoms.
{"title":"Computation-Driven Mechanistic Understanding of the Cellular Cost and Role of Defensive Pigment Production in a Polyextremotolerant Fungus","authors":"Wheaton L. Schroeder, S. Harris, Rajib Saha","doi":"10.2139/ssrn.3528691","DOIUrl":"https://doi.org/10.2139/ssrn.3528691","url":null,"abstract":"The polyextremotolerant black yeast Exophiala dermatitidis is a tractable model system for investigation of adaptations under extreme conditions. Foremost amongst these adaptations is production of the defensive pigments melanins and carotenoids. A particularly important question is their metabolic production cost. However, this investigation has been hindered by a relatively poor systems-level understanding of E. dermatitidis metabolism. To address this challenge, a genome-scale model (iEde2091) was developed. Using iEde2091, carotenoids were found to be more expensive to produce than melanins. Given their overlapping protective functions, this suggests that carotenoids have an underexplored yet important role of photo-protection under high-energy visible light. Furthermore, multiple defensive pigments with overlapping functions might allow E. dermatitidis to minimize cost. Because iEde2091 revealed that E. dermatitidis synthesizes the same melanins as humans and the active sites of the key tyrosinase enzyme are highly conserved, this model may enable a broader understanding of melanin production across kingdoms.","PeriodicalId":18341,"journal":{"name":"Materials Science eJournal","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-03-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77374936","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}
Injectable alginate hydrogels have demonstrated utility in tissue engineering and drug delivery applications due in part to their mild gelation conditions, low host responses and chemical versatility. Recently, the potential of these gels has expanded with the introduction of refillable hydrogel depots - alginate gels chemically decorated with click chemistry groups to efficiently capture prodrug refills from the blood. Unfortunately, high degrees of click group substitution on alginate lead to poor viscoelastic properties and loss of ionic cross-linking. In this work, we introduce tetrabicyclononyne (tBCN) agents that covalently cross-link azide-modified alginate hydrogels for tissue engineering and drug delivery application in vivo. Adjusting cross-linker concentration allowed tuning the hydrogel mechanical properties for tissue-specific mechanical strength. The bioorthogonal and specific click reaction creates stable hydrogels with improved in vivo properties, including improved retention at injected sites. Azide-alginate hydrogels cross-linked with tBCN elicited minimal inflammation and maintained structural integrity over several months and efficiently captured therapeutics drug surrogates from the circulation. Taken together, azide-alginate hydrogels cross-linked with tBCN convey the benefits of alginate hydrogels for use in tissue engineering and drug delivery applications of refillable drug delivery depots. Statement of Significance Ionically cross-linked, injectable alginate biomaterials hold promise in many different clinical settings. However, adding new chemical functionality to alginate can disrupt their ionic cross-linking, limiting their utility. We have developed a "click" cross-linking strategy to improve the mechanical properties and tissue function of modified alginate biomaterials and enable them to capture small molecule drugs from the blood. We show that click cross-linked materials remain in place better than ionically cross-linked materials and efficiently capture payloads from the blood. Development of click cross-linking for refillable depots represents a crucial step toward clinical application of this promising drug delivery platform.
{"title":"Click Cross-Linking Improves Retention and Targeting of Refillable Alginate Depots","authors":"Christopher T. Moody, Sandeep Palvai, Y. Brudno","doi":"10.2139/ssrn.3542984","DOIUrl":"https://doi.org/10.2139/ssrn.3542984","url":null,"abstract":"Injectable alginate hydrogels have demonstrated utility in tissue engineering and drug delivery applications due in part to their mild gelation conditions, low host responses and chemical versatility. Recently, the potential of these gels has expanded with the introduction of refillable hydrogel depots - alginate gels chemically decorated with click chemistry groups to efficiently capture prodrug refills from the blood. Unfortunately, high degrees of click group substitution on alginate lead to poor viscoelastic properties and loss of ionic cross-linking. In this work, we introduce tetrabicyclononyne (tBCN) agents that covalently cross-link azide-modified alginate hydrogels for tissue engineering and drug delivery application in vivo. Adjusting cross-linker concentration allowed tuning the hydrogel mechanical properties for tissue-specific mechanical strength. The bioorthogonal and specific click reaction creates stable hydrogels with improved in vivo properties, including improved retention at injected sites. Azide-alginate hydrogels cross-linked with tBCN elicited minimal inflammation and maintained structural integrity over several months and efficiently captured therapeutics drug surrogates from the circulation. Taken together, azide-alginate hydrogels cross-linked with tBCN convey the benefits of alginate hydrogels for use in tissue engineering and drug delivery applications of refillable drug delivery depots. Statement of Significance Ionically cross-linked, injectable alginate biomaterials hold promise in many different clinical settings. However, adding new chemical functionality to alginate can disrupt their ionic cross-linking, limiting their utility. We have developed a \"click\" cross-linking strategy to improve the mechanical properties and tissue function of modified alginate biomaterials and enable them to capture small molecule drugs from the blood. We show that click cross-linked materials remain in place better than ionically cross-linked materials and efficiently capture payloads from the blood. Development of click cross-linking for refillable depots represents a crucial step toward clinical application of this promising drug delivery platform.","PeriodicalId":18341,"journal":{"name":"Materials Science eJournal","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-03-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85013827","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}
R. K. Nutor, Muhammad Azeemullah, Q. Cao, X. D. Wang, D.X. Zhang, J. Jiang
The microstructure, mechanical and corrosion properties of a cost-effective face-center cubic (fcc)-structured Co-free Fe50Mn27Ni10Cr13 high entropy alloy (HEA), which is developed here, have been studied using a comprehensive approach of ex-situ tensile tests, in-situ SEM/EBSD tensile measurements, ex-situ TEM studies, Tafel polarization, and immersion tests. After thermo-mechanical treatments, this alloy exhibits a tensile strength of 463 MPa and elongation of over 40% which are comparable to other expensive HEAs. A miniature-designed dog-bone specimen for in-situ SEM/EBSD measurements was successfully employed to study the underlying deformation mechanisms of the alloy, exhibiting the double-fiber 〈111〉 and 〈001〉 texture typical of TWIP steels. Nano-, meso- and macro-scale studies revealed that the excellent combination of strength and ductility of this newly-developed cost-effective fcc-structured HEA is originated from the formation of stacking faults and nano-twins during tensile deformation. This newly-developed alloy also exhibits good corrosion resistance in the following solutions: NaCl > NaOH > H2SO4 > HCl. The corrosion resistance was mostly found to be dependent on the amount of Mn-oxide in the passive film formed on the surface of the alloy. This work, following the non-equiatomic HEA design strategy, develops a cost-effective HEA with a good combination of mechanical with corrosion properties, which will trigger more investigations.
{"title":"Microstructure and Properties of a Co-Free Fe50mn27ni10cr13 High Entropy Alloy","authors":"R. K. Nutor, Muhammad Azeemullah, Q. Cao, X. D. Wang, D.X. Zhang, J. Jiang","doi":"10.2139/ssrn.3542973","DOIUrl":"https://doi.org/10.2139/ssrn.3542973","url":null,"abstract":"The microstructure, mechanical and corrosion properties of a cost-effective face-center cubic (fcc)-structured Co-free Fe50Mn27Ni10Cr13 high entropy alloy (HEA), which is developed here, have been studied using a comprehensive approach of ex-situ tensile tests, in-situ SEM/EBSD tensile measurements, ex-situ TEM studies, Tafel polarization, and immersion tests. After thermo-mechanical treatments, this alloy exhibits a tensile strength of 463 MPa and elongation of over 40% which are comparable to other expensive HEAs. A miniature-designed dog-bone specimen for in-situ SEM/EBSD measurements was successfully employed to study the underlying deformation mechanisms of the alloy, exhibiting the double-fiber 〈111〉 and 〈001〉 texture typical of TWIP steels. Nano-, meso- and macro-scale studies revealed that the excellent combination of strength and ductility of this newly-developed cost-effective fcc-structured HEA is originated from the formation of stacking faults and nano-twins during tensile deformation. This newly-developed alloy also exhibits good corrosion resistance in the following solutions: NaCl > NaOH > H2SO4 > HCl. The corrosion resistance was mostly found to be dependent on the amount of Mn-oxide in the passive film formed on the surface of the alloy. This work, following the non-equiatomic HEA design strategy, develops a cost-effective HEA with a good combination of mechanical with corrosion properties, which will trigger more investigations.","PeriodicalId":18341,"journal":{"name":"Materials Science eJournal","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-03-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81731955","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 Many experimental and first principles studies on precipitation hardening alloys show that segregation of elemental species to the matrix-precipitate interphase boundary (IB) reduces the boundary’s energy. This segregation mechanism can thermally stabilize the microstructure against precipitate coarsening processes and allow for higher operating temperatures in structural applications. In this paper, we develop a phase-field modeling framework to describe IB solute segregation in ternary alloys. The interfacial thermodynamics is effectively described by defining an IB phase with a characteristic free energy-concentration dependence. Equilibrium for the IB phase is established via the parallel tangent plane construction, analogous to classical treatments for segregation to free surfaces and grain boundaries. Analytic steady-steady solutions elucidating the dependence of IB properties on bulk phase composition, temperature and model parameters are derived for a one-dimensional system. Analytic relations for the classical thermodynamic quantities–IB energy and relative solute excess–are derived and the Gibbs adsorption equation is shown to hold; therefore, predictions of the model can be compared with experiments and atomistic simulations. An application of the model is demonstrated for Zn segregation to Mg/Mg2Sn using representative IB parameters. A two-particle coarsening simulation of IB segregation is performed: the result demonstrates enhanced coarsening resistance of the ternary alloy relative to the binary alloy.
{"title":"Interphase Boundary Segregation and Precipitate Coarsening Resistance in Ternary Alloys: An Analytic Phase-Field Model Describing Chemical Effects","authors":"S. Kadambi, F. Abdeljawad, S. Patala","doi":"10.2139/ssrn.3539253","DOIUrl":"https://doi.org/10.2139/ssrn.3539253","url":null,"abstract":"Abstract Many experimental and first principles studies on precipitation hardening alloys show that segregation of elemental species to the matrix-precipitate interphase boundary (IB) reduces the boundary’s energy. This segregation mechanism can thermally stabilize the microstructure against precipitate coarsening processes and allow for higher operating temperatures in structural applications. In this paper, we develop a phase-field modeling framework to describe IB solute segregation in ternary alloys. The interfacial thermodynamics is effectively described by defining an IB phase with a characteristic free energy-concentration dependence. Equilibrium for the IB phase is established via the parallel tangent plane construction, analogous to classical treatments for segregation to free surfaces and grain boundaries. Analytic steady-steady solutions elucidating the dependence of IB properties on bulk phase composition, temperature and model parameters are derived for a one-dimensional system. Analytic relations for the classical thermodynamic quantities–IB energy and relative solute excess–are derived and the Gibbs adsorption equation is shown to hold; therefore, predictions of the model can be compared with experiments and atomistic simulations. An application of the model is demonstrated for Zn segregation to Mg/Mg2Sn using representative IB parameters. A two-particle coarsening simulation of IB segregation is performed: the result demonstrates enhanced coarsening resistance of the ternary alloy relative to the binary alloy.","PeriodicalId":18341,"journal":{"name":"Materials Science eJournal","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-02-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90528011","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}
Jin Chu, Li Chen, Zengshuo Mo, A. Aldalbahi, M. El-Newehy, Wu Wang, X. Mo
Aneurysmal subarachnoid hemorrhage caused by intracranial aneurysm is one of the common cerebrovascular diseases can lead to hemorrhagic stroke, brain damage and death. To prevent thrombosis, rapid endothelialization of the lumen of stent is the most critical approaches. In this study, we explored a controlled release covered stent with core-shell nanofibers via emulsion electrospinning for treating aneurysms. By encapsulating atorvastatin calcium (Atv) within the core of poly (L-lactide-co-caprolactone) (PLCL) nanofibers, the release period of Atv was effectively extended. The morphology and inner-structure of the core-shell nanofibers were respectively observed by scanning electron microscopy and transmission electron microscopy. The release of atorvastatin calcium from the nanofiber lasted for more than 10 weeks without serious initial burst release. The nanofiber films could keep complete morphology after degraded for 3 months. The study demonstrated that atorvastatin calcium promoted the synthesis of nitric oxide (NO) in HUVECs and further the proliferation of HUVECs in vitro. Animal studies showed that PLCL-Atv covered stent could separate the aneurysm dome from the blood circulation and obliterate aneurysm. Moreover, the release of Atv could promote the proliferation of HUVECs on nanofiber films and induction of rapid endothelialization.
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