The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Jan Van Humbeeck - One of the best experts on this subject based on the ideXlab platform.
-
r phase transition and related mechanical properties controlled by low temperature aging treatment in a ti 50 8 at ni thin wire
Scripta Materialia, 2014Co-Authors: Xiebin Wang, Dominique Schryvers, Bert Verlinden, Jan Van HumbeeckAbstract:A cold-drawn Ti–50.8 at.% Ni wire was annealed at 600 °C for 30 min, followed by aging at 250 °C for different times. A microstructure with small grains and nanoscaled precipitates was obtained. The thermally induced martensite transformation is suppressed in the samples aged for 4 h or longer, leaving a one-stage R-phase transition between −150 and +150 °C. The transformation behavior, work output and Recovery Stress associated with the R-phase transition are presented.
-
influence of pre strain on Recovery Stress of annealed niti thin wire during isothermal holding
Journal of Alloys and Compounds, 2011Co-Authors: Xiaojun Yan, Jan Van HumbeeckAbstract:The present research aims to understand the Recovery Stress of NiTi wires generated during heating and isothermal holding under constrained condition. Both pre-strain and isothermal holding temperature have significant effects on the evolution of Recovery Stress during heating and isothermal holding. In general, increasing isothermal holding temperature and/or pre-strain causes an increase of Recovery Stress reduction or relaxation. This effect can be attributed to different dislocation densities and mobility of dislocations generated in those conditions.
V Demers - One of the best experts on this subject based on the ideXlab platform.
-
Substructure and Nanocrystalline Structure Effects in Thermomechanically Treated Ti-Ni Alloys
2016Co-Authors: K. E. Inaekyan, S D Prokoshkin, V Demers, Yu I Khmelevskaya, V. Brailovski, S V DobatkinAbstract:structure, functional properties Abstract. Substructure and structure formation as well as functional properties of thermomechanically treated Ti-Ni wire have been studied using differential scanning calorimetry, X-ray diffraction, transmission electron microscopy and mechanical. The low- temperature themomechanical treatment (LTMT) was carried out by rolling at room temperature in a true strain range e = 0.3 to 1.9. It was shown that severe plastic deformation (e=1.9) of Ti-50.0at.%Ni alloy results in partial amorphization and formation of nanocrystalline austenite structure during post-deformation annealings up to 400 ºC. As a result, the fully recoverable strain and Recovery Stress become much higher than the values reachable after traditional LTMT (e=0.3 to 0.88) with post-deformation annealing which creates a poligonized dislocation substructure
-
functional properties of nanocrystalline submicrocrystalline and polygonized ti ni alloys processed by cold rolling and post deformation annealing
Journal of Alloys and Compounds, 2011Co-Authors: Vladimir Brailovski, S D Prokoshkin, Karina Inaekyan, V DemersAbstract:Abstract Thermomechanical processing consisting of cold rolling ( e = 0.3–2.0) and post-deformation annealing (300–450 °C, 1 h) was applied to binary Ti–Ni alloys to produce nanocrystalline structures (NS) or polygonized dislocation substructures (PDS), or their mixture. The evolution of the material structure and properties was studied using TEM, X-ray, microhardness, calorimetry and tensile testing techniques. Recovery Stress and strain of the Ti–50.26 at.%Ni alloy and superelastic strain of the Ti–50.6 at.%Ni alloy were measured under static and fatigue conditions. It was found that higher true yield Stress of NS alloys not only increases the Recovery Stress potential, but, since it is combined with a relatively low transformation yield Stress; it increases the completely recoverable strain. NS alloys generate Recovery Stresses that are twice as high as those of PDS alloys (1200 MPa), completely recoverable strains that are 10% greater (up to 6% in tension), and they demonstrate a higher cyclic stability of shape memory and superelastic properties. This improvement comes with the cost of a lower NS alloy fatigue damage tolerance, aggravated by the presence of microcracks caused by cold working. Binary Ti–Ni alloys, processed by annealing of an intermediately cold-worked ( e = 0.75…1) alloy and containing mixed nanocrystalline structure and polygonized dislocation substructure, allow a high fatigue life combined with relatively high and cyclically stable functional properties.
-
functional properties of nanocrystalline submicrocrystalline and polygonized ti ni alloys processed by cold rolling and post deformation annealing
ESOMAT 2009 - 8th European Symposium on Martensitic Transformations, 2009Co-Authors: Vladimir Brailovski, S D Prokoshkin, Karina Inaekyan, V DemersAbstract:Thermomechanical processing consisting of cold rolling (e=0.3-2.0) and post-deformation annealing (300-450oC, 1h) was applied to binary Ti-Ni alloys to produce nanocrystalline structures (NS) or polygonized dislocation substructures (PDS), or their mixture. The evolution of the material structure and properties was studied using TEM, X-ray, microhardness, calorimetry and tensile testing techniques. Recovery Stress and strain of the 50.26at%Ni alloy and superelastic strain of the Ti-50.6at%Ni alloy were measured under static and fatigue conditions. It was found that higher true yield Stress of NS alloys not only increases the Recovery Stress potential, but, since it is combined with a relatively low transformation yield Stress; it increases the completely recoverable strain. NS alloys generate Recovery Stresses that are twice as high as those of PDS alloys (1200 MPa), completely recoverable strains that are 10% greater (up to 6% in tension), and they demonstrate a higher cyclic stability of functional properties. This improvement comes with the cost of a lower NS alloy fatigue damage tolerance, aggravated by the presence of microcracks caused by cold working. Binary Ti-Ni alloys, processed by annealing of an intermediately cold-worked (e=0.75…1) alloy and containing mixed nanocrystalline structure and polygonized dislocation substructure, allow a high fatigue life combined with relatively high and cyclically stable functional properties.
-
structure and properties of severely cold rolled and annealed ti ni shape memory alloys
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2008Co-Authors: S D Prokoshkin, Vladimir Brailovski, K Inaekyan, V Demers, Yu I Khmelevskaya, S V Dobatkin, E V TatyaninAbstract:Abstract The substructure and structure formation as well as the mechanical and functional properties of thermomechanically treated Ti–50.7 at.%Ni and Ti–50.0 at.%Ni alloys were studied using transmission electron microscopy and mechanical testing. A low-temperature thermomechanical treatment is carried out by rolling at room temperature in a true strain range e = 0.3–1.9. It is shown that the severe plastic deformation of Ti–Ni alloys results in a partial material amorphization and in the subsequent formation of a nanocrystalline austenite structure during post-deformation annealing. As a result, the completely recoverable strain and Recovery Stress become much higher than the values reachable using traditional low-temperature thermomechanical treatment with post-deformation annealing which creates a polygonized dislocation substructure.
-
structure and properties of the ti 50 0 at ni alloy after strain hardening and nanocrystallizing thermomechanical processing
Materials Transactions, 2006Co-Authors: Vladimir Brailovski, S D Prokoshkin, Irina Yu Khmelevskaya, K Inaekyan, V Demers, Sergei V Dobatkin, Evgeny V TatyaninAbstract:The thermomechanical processing consisting in cold work (true strain e ¼ 0:3{1:9) followed by a post-deformation annealing (200–700 � C temperature range) is applied to the equiatomic Ti–Ni alloy. The evolution of the structure, substructure and functional properties of the material is studied. For all levels of cold work, the maxima of the free Recovery strain and constraint Recovery Stress are obtained after annealing in the 350–400 � C temperature range. For a moderately cold-worked material (true strain e ¼ 0:3), this temperature range corresponds to polygonization; for a severely cold-worked material (e ¼ 1:9), it corresponds to the material nanocrystallization, while for a highly cold-worked material (e ¼ 0:88), the structure is mixed. An increase in the cold-work strain leads to an increase in the completely recoverable strain above 8% and in the maximum Recovery Stress up to 1450 MPa, as well as to the widening of the superelastic temperature range.
S D Prokoshkin - One of the best experts on this subject based on the ideXlab platform.
-
Substructure and Nanocrystalline Structure Effects in Thermomechanically Treated Ti-Ni Alloys
2016Co-Authors: K. E. Inaekyan, S D Prokoshkin, V Demers, Yu I Khmelevskaya, V. Brailovski, S V DobatkinAbstract:structure, functional properties Abstract. Substructure and structure formation as well as functional properties of thermomechanically treated Ti-Ni wire have been studied using differential scanning calorimetry, X-ray diffraction, transmission electron microscopy and mechanical. The low- temperature themomechanical treatment (LTMT) was carried out by rolling at room temperature in a true strain range e = 0.3 to 1.9. It was shown that severe plastic deformation (e=1.9) of Ti-50.0at.%Ni alloy results in partial amorphization and formation of nanocrystalline austenite structure during post-deformation annealings up to 400 ºC. As a result, the fully recoverable strain and Recovery Stress become much higher than the values reachable after traditional LTMT (e=0.3 to 0.88) with post-deformation annealing which creates a poligonized dislocation substructure
-
functional properties of nanocrystalline submicrocrystalline and polygonized ti ni alloys processed by cold rolling and post deformation annealing
Journal of Alloys and Compounds, 2011Co-Authors: Vladimir Brailovski, S D Prokoshkin, Karina Inaekyan, V DemersAbstract:Abstract Thermomechanical processing consisting of cold rolling ( e = 0.3–2.0) and post-deformation annealing (300–450 °C, 1 h) was applied to binary Ti–Ni alloys to produce nanocrystalline structures (NS) or polygonized dislocation substructures (PDS), or their mixture. The evolution of the material structure and properties was studied using TEM, X-ray, microhardness, calorimetry and tensile testing techniques. Recovery Stress and strain of the Ti–50.26 at.%Ni alloy and superelastic strain of the Ti–50.6 at.%Ni alloy were measured under static and fatigue conditions. It was found that higher true yield Stress of NS alloys not only increases the Recovery Stress potential, but, since it is combined with a relatively low transformation yield Stress; it increases the completely recoverable strain. NS alloys generate Recovery Stresses that are twice as high as those of PDS alloys (1200 MPa), completely recoverable strains that are 10% greater (up to 6% in tension), and they demonstrate a higher cyclic stability of shape memory and superelastic properties. This improvement comes with the cost of a lower NS alloy fatigue damage tolerance, aggravated by the presence of microcracks caused by cold working. Binary Ti–Ni alloys, processed by annealing of an intermediately cold-worked ( e = 0.75…1) alloy and containing mixed nanocrystalline structure and polygonized dislocation substructure, allow a high fatigue life combined with relatively high and cyclically stable functional properties.
-
functional properties of nanocrystalline submicrocrystalline and polygonized ti ni alloys processed by cold rolling and post deformation annealing
ESOMAT 2009 - 8th European Symposium on Martensitic Transformations, 2009Co-Authors: Vladimir Brailovski, S D Prokoshkin, Karina Inaekyan, V DemersAbstract:Thermomechanical processing consisting of cold rolling (e=0.3-2.0) and post-deformation annealing (300-450oC, 1h) was applied to binary Ti-Ni alloys to produce nanocrystalline structures (NS) or polygonized dislocation substructures (PDS), or their mixture. The evolution of the material structure and properties was studied using TEM, X-ray, microhardness, calorimetry and tensile testing techniques. Recovery Stress and strain of the 50.26at%Ni alloy and superelastic strain of the Ti-50.6at%Ni alloy were measured under static and fatigue conditions. It was found that higher true yield Stress of NS alloys not only increases the Recovery Stress potential, but, since it is combined with a relatively low transformation yield Stress; it increases the completely recoverable strain. NS alloys generate Recovery Stresses that are twice as high as those of PDS alloys (1200 MPa), completely recoverable strains that are 10% greater (up to 6% in tension), and they demonstrate a higher cyclic stability of functional properties. This improvement comes with the cost of a lower NS alloy fatigue damage tolerance, aggravated by the presence of microcracks caused by cold working. Binary Ti-Ni alloys, processed by annealing of an intermediately cold-worked (e=0.75…1) alloy and containing mixed nanocrystalline structure and polygonized dislocation substructure, allow a high fatigue life combined with relatively high and cyclically stable functional properties.
-
structure and properties of severely cold rolled and annealed ti ni shape memory alloys
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2008Co-Authors: S D Prokoshkin, Vladimir Brailovski, K Inaekyan, V Demers, Yu I Khmelevskaya, S V Dobatkin, E V TatyaninAbstract:Abstract The substructure and structure formation as well as the mechanical and functional properties of thermomechanically treated Ti–50.7 at.%Ni and Ti–50.0 at.%Ni alloys were studied using transmission electron microscopy and mechanical testing. A low-temperature thermomechanical treatment is carried out by rolling at room temperature in a true strain range e = 0.3–1.9. It is shown that the severe plastic deformation of Ti–Ni alloys results in a partial material amorphization and in the subsequent formation of a nanocrystalline austenite structure during post-deformation annealing. As a result, the completely recoverable strain and Recovery Stress become much higher than the values reachable using traditional low-temperature thermomechanical treatment with post-deformation annealing which creates a polygonized dislocation substructure.
-
structure and properties of the ti 50 0 at ni alloy after strain hardening and nanocrystallizing thermomechanical processing
Materials Transactions, 2006Co-Authors: Vladimir Brailovski, S D Prokoshkin, Irina Yu Khmelevskaya, K Inaekyan, V Demers, Sergei V Dobatkin, Evgeny V TatyaninAbstract:The thermomechanical processing consisting in cold work (true strain e ¼ 0:3{1:9) followed by a post-deformation annealing (200–700 � C temperature range) is applied to the equiatomic Ti–Ni alloy. The evolution of the structure, substructure and functional properties of the material is studied. For all levels of cold work, the maxima of the free Recovery strain and constraint Recovery Stress are obtained after annealing in the 350–400 � C temperature range. For a moderately cold-worked material (true strain e ¼ 0:3), this temperature range corresponds to polygonization; for a severely cold-worked material (e ¼ 1:9), it corresponds to the material nanocrystallization, while for a highly cold-worked material (e ¼ 0:88), the structure is mixed. An increase in the cold-work strain leads to an increase in the completely recoverable strain above 8% and in the maximum Recovery Stress up to 1450 MPa, as well as to the widening of the superelastic temperature range.
Brij N Agrawal - One of the best experts on this subject based on the ideXlab platform.
-
active position control of a shape memory alloy wire actuated composite beam
Smart Materials and Structures, 2000Co-Authors: Gangbing Song, Brian Kelly, Brij N AgrawalAbstract:This paper presents the design and the experimental result of the active position control of a shape memory alloy (SMA) wire actuated composite beam. The composite beam has a honeycomb structure with SMA wires embedded in one of its face sheets for the active actuation. The potential applications of this experiment include thermo-distortion compensation for precision space structure, stern shape control for submarines, and flap shape control for aeronautical applications. SMA wires are chosen as the actuating elements due to their high Recovery Stress ({>}500 MPa) and tolerance to high strain (up to 6%). However, SMA wires are inherently nonlinear and pose a challenge for control design. A robust controller is designed and implemented to actively control the tip position of the composite beam. The experiment set-up consists of the composite beam with embedded SMA wires, a programmable current/voltage amplifier to actuate the SMA wires, an infrared laser range sensor to detect the beam tip displacement, and a real-time data acquisition and control system. The experimental result demonstrates the effectiveness of the robust control.
-
active position control of a shape memory alloy wire actuated composite beam
Smart Structures and Materials 1999: Mathematics and Control in Smart Structures, 1999Co-Authors: Gangbing Song, Brian Kelly, Brij N AgrawalAbstract:This paper presents the design and experiment results of active position control of a shape memory alloy (SMA) wires actuated composite beam. The composite beam is honeycomb structured with shape memory alloy wires embedded in one of its phase sheet for active actuation. The potential applications of this experiment include thermo-distortion compensation for precession space structure, stern shape control for submarines, and flap shape control for aeronautical applications. Shape memory alloy wires are chosen as actuating elements due to their high Recovery Stress (maybe greater than 700 MPa) and tolerance to high strain (up to 8%). However, shape memory alloy wires are inherently nonlinear and pose a challenge for control design. A robust controller is designed and implemented to active control the tip position of the composite beam. The experiment setup consists of the composite beam with embedded SMA wires, programmable current/voltage amplifier to actuate the SMA wires, an infrared laser range sensor to detect the beam tip displacement, and a real-time data acquisition and control system. Experiments demonstrated the effectiveness of the robust control.
Vladimir Brailovski - One of the best experts on this subject based on the ideXlab platform.
-
functional properties of nanocrystalline submicrocrystalline and polygonized ti ni alloys processed by cold rolling and post deformation annealing
Journal of Alloys and Compounds, 2011Co-Authors: Vladimir Brailovski, S D Prokoshkin, Karina Inaekyan, V DemersAbstract:Abstract Thermomechanical processing consisting of cold rolling ( e = 0.3–2.0) and post-deformation annealing (300–450 °C, 1 h) was applied to binary Ti–Ni alloys to produce nanocrystalline structures (NS) or polygonized dislocation substructures (PDS), or their mixture. The evolution of the material structure and properties was studied using TEM, X-ray, microhardness, calorimetry and tensile testing techniques. Recovery Stress and strain of the Ti–50.26 at.%Ni alloy and superelastic strain of the Ti–50.6 at.%Ni alloy were measured under static and fatigue conditions. It was found that higher true yield Stress of NS alloys not only increases the Recovery Stress potential, but, since it is combined with a relatively low transformation yield Stress; it increases the completely recoverable strain. NS alloys generate Recovery Stresses that are twice as high as those of PDS alloys (1200 MPa), completely recoverable strains that are 10% greater (up to 6% in tension), and they demonstrate a higher cyclic stability of shape memory and superelastic properties. This improvement comes with the cost of a lower NS alloy fatigue damage tolerance, aggravated by the presence of microcracks caused by cold working. Binary Ti–Ni alloys, processed by annealing of an intermediately cold-worked ( e = 0.75…1) alloy and containing mixed nanocrystalline structure and polygonized dislocation substructure, allow a high fatigue life combined with relatively high and cyclically stable functional properties.
-
functional properties of nanocrystalline submicrocrystalline and polygonized ti ni alloys processed by cold rolling and post deformation annealing
ESOMAT 2009 - 8th European Symposium on Martensitic Transformations, 2009Co-Authors: Vladimir Brailovski, S D Prokoshkin, Karina Inaekyan, V DemersAbstract:Thermomechanical processing consisting of cold rolling (e=0.3-2.0) and post-deformation annealing (300-450oC, 1h) was applied to binary Ti-Ni alloys to produce nanocrystalline structures (NS) or polygonized dislocation substructures (PDS), or their mixture. The evolution of the material structure and properties was studied using TEM, X-ray, microhardness, calorimetry and tensile testing techniques. Recovery Stress and strain of the 50.26at%Ni alloy and superelastic strain of the Ti-50.6at%Ni alloy were measured under static and fatigue conditions. It was found that higher true yield Stress of NS alloys not only increases the Recovery Stress potential, but, since it is combined with a relatively low transformation yield Stress; it increases the completely recoverable strain. NS alloys generate Recovery Stresses that are twice as high as those of PDS alloys (1200 MPa), completely recoverable strains that are 10% greater (up to 6% in tension), and they demonstrate a higher cyclic stability of functional properties. This improvement comes with the cost of a lower NS alloy fatigue damage tolerance, aggravated by the presence of microcracks caused by cold working. Binary Ti-Ni alloys, processed by annealing of an intermediately cold-worked (e=0.75…1) alloy and containing mixed nanocrystalline structure and polygonized dislocation substructure, allow a high fatigue life combined with relatively high and cyclically stable functional properties.
-
structure and properties of severely cold rolled and annealed ti ni shape memory alloys
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2008Co-Authors: S D Prokoshkin, Vladimir Brailovski, K Inaekyan, V Demers, Yu I Khmelevskaya, S V Dobatkin, E V TatyaninAbstract:Abstract The substructure and structure formation as well as the mechanical and functional properties of thermomechanically treated Ti–50.7 at.%Ni and Ti–50.0 at.%Ni alloys were studied using transmission electron microscopy and mechanical testing. A low-temperature thermomechanical treatment is carried out by rolling at room temperature in a true strain range e = 0.3–1.9. It is shown that the severe plastic deformation of Ti–Ni alloys results in a partial material amorphization and in the subsequent formation of a nanocrystalline austenite structure during post-deformation annealing. As a result, the completely recoverable strain and Recovery Stress become much higher than the values reachable using traditional low-temperature thermomechanical treatment with post-deformation annealing which creates a polygonized dislocation substructure.
-
structure and properties of the ti 50 0 at ni alloy after strain hardening and nanocrystallizing thermomechanical processing
Materials Transactions, 2006Co-Authors: Vladimir Brailovski, S D Prokoshkin, Irina Yu Khmelevskaya, K Inaekyan, V Demers, Sergei V Dobatkin, Evgeny V TatyaninAbstract:The thermomechanical processing consisting in cold work (true strain e ¼ 0:3{1:9) followed by a post-deformation annealing (200–700 � C temperature range) is applied to the equiatomic Ti–Ni alloy. The evolution of the structure, substructure and functional properties of the material is studied. For all levels of cold work, the maxima of the free Recovery strain and constraint Recovery Stress are obtained after annealing in the 350–400 � C temperature range. For a moderately cold-worked material (true strain e ¼ 0:3), this temperature range corresponds to polygonization; for a severely cold-worked material (e ¼ 1:9), it corresponds to the material nanocrystallization, while for a highly cold-worked material (e ¼ 0:88), the structure is mixed. An increase in the cold-work strain leads to an increase in the completely recoverable strain above 8% and in the maximum Recovery Stress up to 1450 MPa, as well as to the widening of the superelastic temperature range.