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Kaushik Chatterjee - One of the best experts on this subject based on the ideXlab platform.
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Surface nanostructuring of titanium imparts multifunctional properties for orthopedic and cardiovascular applications
Materials & Design, 2018Co-Authors: Sumit Bahl, Satyam Suwas, Bhavya Tulasi Aleti, Kaushik ChatterjeeAbstract:Abstract Commercially pure titanium (cp-Ti) is a metallic biomaterial used in orthopedic and cardiovascular applications. Here, surface nanocrystalline cp-Ti produced by surface mechanical attrition treatment (SMAT) is shown to exhibit multifunctional properties for orthopedic and cardiovascular applications. Nanocrystallization simultaneously enhanced the stem cell response and fatigue resistance in simulated body fluid of cp-Ti collectively required for load bearing orthopedic applications. Stem cell attachment and proliferation was enhanced by 20% and number of cycles to failure increased by 15% after Nanocrystallization. Nanocrystalline Ti was also found to be suitable for cardiovascular applications due to its improved hemocompatibility. A 40% reduction in attachment of platelets and their activation was noted on the surface of nanocrystalline Ti. While high surface hardness and compressive residual stress improved the corrosion-fatigue resistance, the biological response of stem cells and platelets was governed by the physico-electro-chemical properties of the surface oxide on cp-Ti. Modulation in properties of the oxide layer altered the protein adsorption, evaluated by means of electrochemical impedance spectroscopy and direct protein quantification thereby, augmenting the biological response. Taken together, it is demonstrated that surface Nanocrystallization by SMAT is a promising step towards producing high performance Ti implants for orthopedic and cardiovascular applications.
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Elucidating microstructural evolution and strengthening mechanisms in nanocrystalline surface induced by surface mechanical attrition treatment of stainless steel
Acta Materialia, 2016Co-Authors: Sumit Bahl, Tamás Ungár, Satyam Suwas, Kaushik ChatterjeeAbstract:Surface mechanical attrition treatment (SMAT) is a high strain and strain rate severe plastic deformation (SPD) technique for surface Nanocrystallization of metals. The aim of this study was to investigate the mechanism of Nanocrystallization and strengthening in a medium stacking fault energy 316 L austenitic stainless steel during SMAT. The paramount role of microband and shear band formation in nano crystallization is outlined, as opposed to deformation twinning previously reported in low SFE austenitic stainless steels. Shear bands undergo dynamic recrystallization and recrystallization twinning to produce ultra-fine grains in contrast to twin-twin intersections in low SFE stainless steel. The ultra-fine grains further sub-divide into smaller cells with initially low misorientation. Nanocrystallization occurs when misorientation between these cells increases with further strain. The additivity of strengthening by dislocation density and grain size is studied. Dislocation density was neglected in previous studies while studying strengthening mechanisms in SMAT processed materials. This study illustrates that dislocation density cannot be ignored as the strengthening mechanism in SMAT process. The grain size and dislocation density both significantly contribute to overall strengthening in SMAT processed microstructure. (C) 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
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enhancing the mechanical and biological performance of a metallic biomaterial for orthopedic applications through changes in the surface oxide layer by nanocrystalline surface modification
Nanoscale, 2015Co-Authors: Sumit Bahl, Satyam Suwas, P Shreyas, M A Trishul, Kaushik ChatterjeeAbstract:Nanostructured metals are a promising class of biomaterials for application in orthopedics to improve the mechanical performance and biological response for increasing the life of biomedical implants. Surface mechanical attrition treatment (SMAT) is an efficient way of engineering nanocrystalline surfaces on metal substrates. In this work, 316L stainless steel (SS), a widely used orthopedic biomaterial, was subjected to SMAT to generate a nanocrystalline surface. Surface Nanocrystallization modified the nature of the oxide layer present on the surface. It increased the corrosion-fatigue strength in saline by 50%. This increase in strength is attributed to a thicker oxide layer, residual compressive stresses, high strength of the surface layer, and lower propensity for intergranular corrosion in the nanocrystalline layer. Nanocrystallization also enhanced osteoblast attachment and proliferation. Intriguingly, wettability and surface roughness, the key parameters widely acknowledged for controlling the cellular response remained unchanged after Nanocrystallization. The observed cellular behavior is explained in terms of the changes in electronic properties of the semiconducting passive oxide film present on the surface of 316L SS. Nanocrystallization increased the charge carrier density of the n-type oxide film likely preventing denaturation of the adsorbed cell-adhesive proteins such as fibronectin. In addition, a net positive charge developed on the otherwise neutral oxide layer, which is known to facilitate cellular adhesion. The role of changes in the electronic properties of the oxide films on metal substrates is thus highlighted in this work. This study demonstrates the advantages of nanocrystalline surface modification by SMAT for processing metallic biomaterials used in orthopedic implants.
Sumit Bahl - One of the best experts on this subject based on the ideXlab platform.
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Surface nanostructuring of titanium imparts multifunctional properties for orthopedic and cardiovascular applications
Materials & Design, 2018Co-Authors: Sumit Bahl, Satyam Suwas, Bhavya Tulasi Aleti, Kaushik ChatterjeeAbstract:Abstract Commercially pure titanium (cp-Ti) is a metallic biomaterial used in orthopedic and cardiovascular applications. Here, surface nanocrystalline cp-Ti produced by surface mechanical attrition treatment (SMAT) is shown to exhibit multifunctional properties for orthopedic and cardiovascular applications. Nanocrystallization simultaneously enhanced the stem cell response and fatigue resistance in simulated body fluid of cp-Ti collectively required for load bearing orthopedic applications. Stem cell attachment and proliferation was enhanced by 20% and number of cycles to failure increased by 15% after Nanocrystallization. Nanocrystalline Ti was also found to be suitable for cardiovascular applications due to its improved hemocompatibility. A 40% reduction in attachment of platelets and their activation was noted on the surface of nanocrystalline Ti. While high surface hardness and compressive residual stress improved the corrosion-fatigue resistance, the biological response of stem cells and platelets was governed by the physico-electro-chemical properties of the surface oxide on cp-Ti. Modulation in properties of the oxide layer altered the protein adsorption, evaluated by means of electrochemical impedance spectroscopy and direct protein quantification thereby, augmenting the biological response. Taken together, it is demonstrated that surface Nanocrystallization by SMAT is a promising step towards producing high performance Ti implants for orthopedic and cardiovascular applications.
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Elucidating microstructural evolution and strengthening mechanisms in nanocrystalline surface induced by surface mechanical attrition treatment of stainless steel
Acta Materialia, 2016Co-Authors: Sumit Bahl, Tamás Ungár, Satyam Suwas, Kaushik ChatterjeeAbstract:Surface mechanical attrition treatment (SMAT) is a high strain and strain rate severe plastic deformation (SPD) technique for surface Nanocrystallization of metals. The aim of this study was to investigate the mechanism of Nanocrystallization and strengthening in a medium stacking fault energy 316 L austenitic stainless steel during SMAT. The paramount role of microband and shear band formation in nano crystallization is outlined, as opposed to deformation twinning previously reported in low SFE austenitic stainless steels. Shear bands undergo dynamic recrystallization and recrystallization twinning to produce ultra-fine grains in contrast to twin-twin intersections in low SFE stainless steel. The ultra-fine grains further sub-divide into smaller cells with initially low misorientation. Nanocrystallization occurs when misorientation between these cells increases with further strain. The additivity of strengthening by dislocation density and grain size is studied. Dislocation density was neglected in previous studies while studying strengthening mechanisms in SMAT processed materials. This study illustrates that dislocation density cannot be ignored as the strengthening mechanism in SMAT process. The grain size and dislocation density both significantly contribute to overall strengthening in SMAT processed microstructure. (C) 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
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enhancing the mechanical and biological performance of a metallic biomaterial for orthopedic applications through changes in the surface oxide layer by nanocrystalline surface modification
Nanoscale, 2015Co-Authors: Sumit Bahl, Satyam Suwas, P Shreyas, M A Trishul, Kaushik ChatterjeeAbstract:Nanostructured metals are a promising class of biomaterials for application in orthopedics to improve the mechanical performance and biological response for increasing the life of biomedical implants. Surface mechanical attrition treatment (SMAT) is an efficient way of engineering nanocrystalline surfaces on metal substrates. In this work, 316L stainless steel (SS), a widely used orthopedic biomaterial, was subjected to SMAT to generate a nanocrystalline surface. Surface Nanocrystallization modified the nature of the oxide layer present on the surface. It increased the corrosion-fatigue strength in saline by 50%. This increase in strength is attributed to a thicker oxide layer, residual compressive stresses, high strength of the surface layer, and lower propensity for intergranular corrosion in the nanocrystalline layer. Nanocrystallization also enhanced osteoblast attachment and proliferation. Intriguingly, wettability and surface roughness, the key parameters widely acknowledged for controlling the cellular response remained unchanged after Nanocrystallization. The observed cellular behavior is explained in terms of the changes in electronic properties of the semiconducting passive oxide film present on the surface of 316L SS. Nanocrystallization increased the charge carrier density of the n-type oxide film likely preventing denaturation of the adsorbed cell-adhesive proteins such as fibronectin. In addition, a net positive charge developed on the otherwise neutral oxide layer, which is known to facilitate cellular adhesion. The role of changes in the electronic properties of the oxide films on metal substrates is thus highlighted in this work. This study demonstrates the advantages of nanocrystalline surface modification by SMAT for processing metallic biomaterials used in orthopedic implants.
Dierk Raabe - One of the best experts on this subject based on the ideXlab platform.
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atom probe tomography study of ultrahigh Nanocrystallization rates in fesinbbcu soft magnetic amorphous alloys on rapid annealing
Acta Materialia, 2014Co-Authors: Konda Gokuldoss Pradeep, G Herzer, Pyuckpa Choi, Dierk RaabeAbstract:Abstract Rapid annealing (4–10 s) induced primary crystallization of soft magnetic Fe–Si nanocrystals in a Fe 73.5 Si 15.5 Cu 1 Nb 3 B 7 amorphous alloy has been systematically studied by atom probe tomography in comparison with conventional annealing (30–60 min). It was found that the nanostructure obtained after rapid annealing is basically the same, irrespective of the different time scales of annealing. This underlines the crucial role of Cu during structure formation. Accordingly, the clustering of Cu atoms starts at least 50 °C below the onset temperature of primary crystallization. As a consequence, coarsening of Cu atomic clusters also starts prior to crystallization, resulting in a reduction of available nucleation sites during Fe–Si Nanocrystallization. Furthermore, the experimental results explicitly show that these Cu clusters initially induce a local enrichment of Fe and Si in the amorphous matrix. These local chemical heterogeneities are proposed to be the actual nuclei for subsequent Nanocrystallization. Nevertheless, rapid annealing in comparison with conventional annealing results in the formation of ∼30% smaller Fe–Si nanocrystals, but of identical structure, volume fraction and chemical composition, indicating the limited influence of thermal treatment on Nanocrystallization, owing to the effect of Cu.
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atom probe tomography study of ultrahigh Nanocrystallization rates in fesinbbcu soft magnetic amorphous alloys on rapid annealing
Acta Materialia, 2014Co-Authors: Konda Gokuldoss Pradeep, G Herzer, Pyuckpa Choi, Dierk RaabeAbstract:Rapid annealing (4–10 s) induced primary crystallization of soft magnetic Fe–Si nanocrystals in a Fe73.5Si15.5Cu1Nb3B7 amorphous alloy has been systematically studied by atom probe tomography in comparison with conventional annealing (30–60 min). It was found that the nanostructure obtained after rapid annealing is basically the same, irrespective of the different time scales of annealing. This underlines the crucial role of Cu during structure formation. Accordingly, the clustering of Cu atoms starts at least 50 C below the onset temperature of primary crystallization. As a consequence, coarsening of Cu atomic clusters also starts prior to crystallization, resulting in a reduction of available nucleation sites during Fe–Si Nanocrystallization. Furthermore, the experimental results explicitly show that these Cu clusters initially induce a local enrichment of Fe and Si in the amorphous matrix. These local chemical heterogeneities are proposed to be the actual nuclei for subsequent Nanocrystallization. Nevertheless, rapid annealing in comparison with conventional annealing results in the formation of � 30% smaller Fe–Si nanocrystals, but of identical structure, volume fraction and chemical composition, indicating the limited influence of thermal treatment on Nanocrystallization, owing to the effect of Cu. 2014 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
Satyam Suwas - One of the best experts on this subject based on the ideXlab platform.
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Surface nanostructuring of titanium imparts multifunctional properties for orthopedic and cardiovascular applications
Materials & Design, 2018Co-Authors: Sumit Bahl, Satyam Suwas, Bhavya Tulasi Aleti, Kaushik ChatterjeeAbstract:Abstract Commercially pure titanium (cp-Ti) is a metallic biomaterial used in orthopedic and cardiovascular applications. Here, surface nanocrystalline cp-Ti produced by surface mechanical attrition treatment (SMAT) is shown to exhibit multifunctional properties for orthopedic and cardiovascular applications. Nanocrystallization simultaneously enhanced the stem cell response and fatigue resistance in simulated body fluid of cp-Ti collectively required for load bearing orthopedic applications. Stem cell attachment and proliferation was enhanced by 20% and number of cycles to failure increased by 15% after Nanocrystallization. Nanocrystalline Ti was also found to be suitable for cardiovascular applications due to its improved hemocompatibility. A 40% reduction in attachment of platelets and their activation was noted on the surface of nanocrystalline Ti. While high surface hardness and compressive residual stress improved the corrosion-fatigue resistance, the biological response of stem cells and platelets was governed by the physico-electro-chemical properties of the surface oxide on cp-Ti. Modulation in properties of the oxide layer altered the protein adsorption, evaluated by means of electrochemical impedance spectroscopy and direct protein quantification thereby, augmenting the biological response. Taken together, it is demonstrated that surface Nanocrystallization by SMAT is a promising step towards producing high performance Ti implants for orthopedic and cardiovascular applications.
-
Elucidating microstructural evolution and strengthening mechanisms in nanocrystalline surface induced by surface mechanical attrition treatment of stainless steel
Acta Materialia, 2016Co-Authors: Sumit Bahl, Tamás Ungár, Satyam Suwas, Kaushik ChatterjeeAbstract:Surface mechanical attrition treatment (SMAT) is a high strain and strain rate severe plastic deformation (SPD) technique for surface Nanocrystallization of metals. The aim of this study was to investigate the mechanism of Nanocrystallization and strengthening in a medium stacking fault energy 316 L austenitic stainless steel during SMAT. The paramount role of microband and shear band formation in nano crystallization is outlined, as opposed to deformation twinning previously reported in low SFE austenitic stainless steels. Shear bands undergo dynamic recrystallization and recrystallization twinning to produce ultra-fine grains in contrast to twin-twin intersections in low SFE stainless steel. The ultra-fine grains further sub-divide into smaller cells with initially low misorientation. Nanocrystallization occurs when misorientation between these cells increases with further strain. The additivity of strengthening by dislocation density and grain size is studied. Dislocation density was neglected in previous studies while studying strengthening mechanisms in SMAT processed materials. This study illustrates that dislocation density cannot be ignored as the strengthening mechanism in SMAT process. The grain size and dislocation density both significantly contribute to overall strengthening in SMAT processed microstructure. (C) 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
-
enhancing the mechanical and biological performance of a metallic biomaterial for orthopedic applications through changes in the surface oxide layer by nanocrystalline surface modification
Nanoscale, 2015Co-Authors: Sumit Bahl, Satyam Suwas, P Shreyas, M A Trishul, Kaushik ChatterjeeAbstract:Nanostructured metals are a promising class of biomaterials for application in orthopedics to improve the mechanical performance and biological response for increasing the life of biomedical implants. Surface mechanical attrition treatment (SMAT) is an efficient way of engineering nanocrystalline surfaces on metal substrates. In this work, 316L stainless steel (SS), a widely used orthopedic biomaterial, was subjected to SMAT to generate a nanocrystalline surface. Surface Nanocrystallization modified the nature of the oxide layer present on the surface. It increased the corrosion-fatigue strength in saline by 50%. This increase in strength is attributed to a thicker oxide layer, residual compressive stresses, high strength of the surface layer, and lower propensity for intergranular corrosion in the nanocrystalline layer. Nanocrystallization also enhanced osteoblast attachment and proliferation. Intriguingly, wettability and surface roughness, the key parameters widely acknowledged for controlling the cellular response remained unchanged after Nanocrystallization. The observed cellular behavior is explained in terms of the changes in electronic properties of the semiconducting passive oxide film present on the surface of 316L SS. Nanocrystallization increased the charge carrier density of the n-type oxide film likely preventing denaturation of the adsorbed cell-adhesive proteins such as fibronectin. In addition, a net positive charge developed on the otherwise neutral oxide layer, which is known to facilitate cellular adhesion. The role of changes in the electronic properties of the oxide films on metal substrates is thus highlighted in this work. This study demonstrates the advantages of nanocrystalline surface modification by SMAT for processing metallic biomaterials used in orthopedic implants.
Konda Gokuldoss Pradeep - One of the best experts on this subject based on the ideXlab platform.
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atom probe tomography study of ultrahigh Nanocrystallization rates in fesinbbcu soft magnetic amorphous alloys on rapid annealing
Acta Materialia, 2014Co-Authors: Konda Gokuldoss Pradeep, G Herzer, Pyuckpa Choi, Dierk RaabeAbstract:Abstract Rapid annealing (4–10 s) induced primary crystallization of soft magnetic Fe–Si nanocrystals in a Fe 73.5 Si 15.5 Cu 1 Nb 3 B 7 amorphous alloy has been systematically studied by atom probe tomography in comparison with conventional annealing (30–60 min). It was found that the nanostructure obtained after rapid annealing is basically the same, irrespective of the different time scales of annealing. This underlines the crucial role of Cu during structure formation. Accordingly, the clustering of Cu atoms starts at least 50 °C below the onset temperature of primary crystallization. As a consequence, coarsening of Cu atomic clusters also starts prior to crystallization, resulting in a reduction of available nucleation sites during Fe–Si Nanocrystallization. Furthermore, the experimental results explicitly show that these Cu clusters initially induce a local enrichment of Fe and Si in the amorphous matrix. These local chemical heterogeneities are proposed to be the actual nuclei for subsequent Nanocrystallization. Nevertheless, rapid annealing in comparison with conventional annealing results in the formation of ∼30% smaller Fe–Si nanocrystals, but of identical structure, volume fraction and chemical composition, indicating the limited influence of thermal treatment on Nanocrystallization, owing to the effect of Cu.
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atom probe tomography study of ultrahigh Nanocrystallization rates in fesinbbcu soft magnetic amorphous alloys on rapid annealing
Acta Materialia, 2014Co-Authors: Konda Gokuldoss Pradeep, G Herzer, Pyuckpa Choi, Dierk RaabeAbstract:Rapid annealing (4–10 s) induced primary crystallization of soft magnetic Fe–Si nanocrystals in a Fe73.5Si15.5Cu1Nb3B7 amorphous alloy has been systematically studied by atom probe tomography in comparison with conventional annealing (30–60 min). It was found that the nanostructure obtained after rapid annealing is basically the same, irrespective of the different time scales of annealing. This underlines the crucial role of Cu during structure formation. Accordingly, the clustering of Cu atoms starts at least 50 C below the onset temperature of primary crystallization. As a consequence, coarsening of Cu atomic clusters also starts prior to crystallization, resulting in a reduction of available nucleation sites during Fe–Si Nanocrystallization. Furthermore, the experimental results explicitly show that these Cu clusters initially induce a local enrichment of Fe and Si in the amorphous matrix. These local chemical heterogeneities are proposed to be the actual nuclei for subsequent Nanocrystallization. Nevertheless, rapid annealing in comparison with conventional annealing results in the formation of � 30% smaller Fe–Si nanocrystals, but of identical structure, volume fraction and chemical composition, indicating the limited influence of thermal treatment on Nanocrystallization, owing to the effect of Cu. 2014 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
