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Ke Hua - One of the best experts on this subject based on the ideXlab platform.
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Caractéristiques displacives de la transformation de phase de β en α et ses conséquences sur le comportement en déformation à chaud dans l'alliage métastable β Ti-7333
2019Co-Authors: Ke HuaAbstract:Une étude approfondie a été menée sur l’alliage Ti-7333 en termes de transformation de phase β en α. Il a été montré que la transformation de la structure est réalisée par une contraction dansβ, un allongement dans β et β, et un cisaillement sur le système de glissement{1"1" ̅"2" ̅}ββ. Chaque précipité α est composé de deux types de domaines α de taille nanométrique. L'un est situé sur la face large du précipité α majeur (Interface α), l'autre traverse le α majeur (α pénétrant). La nucléation de cet α est induite par la contrainte importante de cisaillement générée par la formation du α majeur. Le α pénétrant n'obéit pas au BOR avec la matrice β mais. La nucléation de cet α est induite par la plus grande contrainte normale générée par la formation de la plaque α principale. La sélection des variantes α lors de la déformation à chaud à 700 °C s'effectue en fonction de la perfection cristalline locale des grains β. Dans les grains β légèrement déformés, 2 variantes de BOR liées. Les variantes sélectionnées apportent une contribution maximale à la déformation macroscopique et subissent la contrainte de cisaillement résolue maximale de la charge externe résolue sur leurs systèmes de transformation {1"1" ̅"2" ̅}ββ. Dans les grains β fortement déformés occupés principalement par des bandes de glissement, 2 à 4 variantes de BOR sont sélectionnées. Le critère de sélection est toujours respecté mais avec une restriction de la déformation locale. Le comportement en déformation lors de la compression à 700 °C présente trois stades contraintes-déformations caractéristiques : un stade linéaire (stade I), un stade d’écoulement discontinu (stade II) et un stade stable (stade III). À la fin du stade I, plus de 90% des joints de grains β sont occupés par des joints de grains α (αGB). Le rendement discontinu du stade II provient de la fragmentation de αGB et de la formation intensive de dislocations mobiles près des joints de grains β. L'état d'équilibre du stade III résulte de deux modes de déformation. Pour ceux dont l'orientation d'activation est favorable pour leurs systèmes {110}ββ par rapport à la charge de compression, la déformation est réalisée par le glissement de dislocation et par la formation de bandes de glissement; alors que pour ceux avec leur {1"1" ̅"2" ̅}ββ systèmes - le système de transformation de β à α - dans des orientations favorables, la déformation est obtenue par formation intensive de précipités α intragranulaires.A thorough investigation has been conducted on the Ti-7333 alloy in terms of the β to α phase transformation. It was revealed that the structure transformation is realized by a contraction in the β, an elongation in the β and β, and a shear on the {1"1" ̅"2" ̅}ββ slip system. Each α precipitate is composed of two kinds of nano-sized α domains. One is situated on the broad face of the major α precipitate (Named Interface α), and the other goes through the major α (termed penetrating α). The nucleation of such α is induced by the large shear strain generated by the formation of the major α. The penetrating α does not obey the BOR with the β matrix. The nucleation of such α is induced by the largest normal strain generated by the formation of the main α plate. The selection of the α variants during hot deformation at 700°C happens with dependence on the local crystal perfection of the β grains. In the slightly deformed β grains, 2 BOR variants are formed ‘cross-shaped’ clusters. The selected variants make maximum contribution to the macroscopic deformation and receive the maximum resolved shear stress from the external load resolved on their {1"1" ̅"2" ̅}ββ systems for transformation. In the heavily deformed β grains occupied mainly by dislocation slip, 2 to 4 BOR variants are selected in smaller numbers. The selection criterion is still obeyed but with restriction from the local deformation. The deformation behavior during 700°C compression presents three characteristic stress-strain stages: a linear stage (Stage I), a discontinuous yielding (Stage II) and a steady-state (Stage III). At the end of Stage I, more than 90% of the β boundaries are occupied by grain boundaries α (αGB). The discontinuous yielding of Stage II originated from the fragmentation of the αGB and the intensive formation of mobile dislocations near the β grain boundary areas. The steady-state of Stage III arises from two orientation dependent deformation modes of the β grains. For those in favorable activation orientation for their {110}ββ systems with respect to the external compressive load, the deformation is realized by the dislocation slip and by the formation of slip bands; whereas for those with their {1"1" ̅"2" ̅}ββ systems - the system for β to α transformation - in favorable orientations, the deformation is achieved by intensive formation of intragranular α precipitates
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Displacive characteristics of β to α phase transformation and its impact on hot deformation behavior in Ti-7333 metastable β titanium alloy
2019Co-Authors: Ke HuaAbstract:A thorough investigation has been conducted on the Ti-7333 alloy in terms of the β to α phase transformation. It was revealed that the structure transformation is realized by a contraction in the β, an elongation in the β and β, and a shear on the {1"1" ̅"2" ̅}ββ slip system. Each α precipitate is composed of two kinds of nano-sized α domains. One is situated on the broad face of the major α precipitate (Named Interface α), and the other goes through the major α (termed penetrating α). The nucleation of such α is induced by the large shear strain generated by the formation of the major α. The penetrating α does not obey the BOR with the β matrix. The nucleation of such α is induced by the largest normal strain generated by the formation of the main α plate. The selection of the α variants during hot deformation at 700°C happens with dependence on the local crystal perfection of the β grains. In the slightly deformed β grains, 2 BOR variants are formed ‘cross-shaped’ clusters. The selected variants make maximum contribution to the macroscopic deformation and receive the maximum resolved shear stress from the external load resolved on their {1"1" ̅"2" ̅}ββ systems for transformation. In the heavily deformed β grains occupied mainly by dislocation slip, 2 to 4 BOR variants are selected in smaller numbers. The selection criterion is still obeyed but with restriction from the local deformation. The deformation behavior during 700°C compression presents three characteristic stress-strain stages: a linear stage (Stage I), a discontinuous yielding (Stage II) and a steady-state (Stage III). At the end of Stage I, more than 90% of the β boundaries are occupied by grain boundaries α (αGB). The discontinuous yielding of Stage II originated from the fragmentation of the αGB and the intensive formation of mobile dislocations near the β grain boundary areas. The steady-state of Stage III arises from two orientation dependent deformation modes of the β grains. For those in favorable activation orientation for their {110}ββ systems with respect to the external compressive load, the deformation is realized by the dislocation slip and by the formation of slip bands; whereas for those with their {1"1" ̅"2" ̅}ββ systems - the system for β to α transformation - in favorable orientations, the deformation is achieved by intensive formation of intragranular α precipitates.
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Caractéristiques displacives de la transformation de phase de β en α et ses conséquences sur le comportement en déformation à chaud dans l'alliage métastable β Ti-7333
HAL CCSD, 2019Co-Authors: Ke HuaAbstract:Texte intégral accessible uniquement aux membres de l'Université de Lorraine jusqu'au 1er avril 2020.A thorough investigation has been conducted on the Ti-7333 alloy in terms of the β to α phase transformation. It was revealed that the structure transformation is realized by a contraction in the β, an elongation in the β and β, and a shear on the {1"1" ̅"2" ̅}ββ slip system. Each α precipitate is composed of two kinds of nano-sized α domains. One is situated on the broad face of the major α precipitate (Named Interface α), and the other goes through the major α (termed penetrating α). The nucleation of such α is induced by the large shear strain generated by the formation of the major α. The penetrating α does not obey the BOR with the β matrix. The nucleation of such α is induced by the largest normal strain generated by the formation of the main α plate. The selection of the α variants during hot deformation at 700°C happens with dependence on the local crystal perfection of the β grains. In the slightly deformed β grains, 2 BOR variants are formed ‘cross-shaped’ clusters. The selected variants make maximum contribution to the macroscopic deformation and receive the maximum resolved shear stress from the external load resolved on their {1"1" ̅"2" ̅}ββ systems for transformation. In the heavily deformed β grains occupied mainly by dislocation slip, 2 to 4 BOR variants are selected in smaller numbers. The selection criterion is still obeyed but with restriction from the local deformation. The deformation behavior during 700°C compression presents three characteristic stress-strain stages: a linear stage (Stage I), a discontinuous yielding (Stage II) and a steady-state (Stage III). At the end of Stage I, more than 90% of the β boundaries are occupied by grain boundaries α (αGB). The discontinuous yielding of Stage II originated from the fragmentation of the αGB and the intensive formation of mobile dislocations near the β grain boundary areas. The steady-state of Stage III arises from two orientation dependent deformation modes of the β grains. For those in favorable activation orientation for their {110}ββ systems with respect to the external compressive load, the deformation is realized by the dislocation slip and by the formation of slip bands; whereas for those with their {1"1" ̅"2" ̅}ββ systems - the system for β to α transformation - in favorable orientations, the deformation is achieved by intensive formation of intragranular α precipitates.Une étude approfondie a été menée sur l’alliage Ti-7333 en termes de transformation de phase β en α. Il a été montré que la transformation de la structure est réalisée par une contraction dansβ, un allongement dans β et β, et un cisaillement sur le système de glissement{1"1" ̅"2" ̅}ββ. Chaque précipité α est composé de deux types de domaines α de taille nanométrique. L'un est situé sur la face large du précipité α majeur (Interface α), l'autre traverse le α majeur (α pénétrant). La nucléation de cet α est induite par la contrainte importante de cisaillement générée par la formation du α majeur. Le α pénétrant n'obéit pas au BOR avec la matrice β mais. La nucléation de cet α est induite par la plus grande contrainte normale générée par la formation de la plaque α principale. La sélection des variantes α lors de la déformation à chaud à 700 °C s'effectue en fonction de la perfection cristalline locale des grains β. Dans les grains β légèrement déformés, 2 variantes de BOR liées. Les variantes sélectionnées apportent une contribution maximale à la déformation macroscopique et subissent la contrainte de cisaillement résolue maximale de la charge externe résolue sur leurs systèmes de transformation {1"1" ̅"2" ̅}ββ. Dans les grains β fortement déformés occupés principalement par des bandes de glissement, 2 à 4 variantes de BOR sont sélectionnées. Le critère de sélection est toujours respecté mais avec une restriction de la déformation locale. Le comportement en déformation lors de la compression à 700 °C présente trois stades contraintes-déformations caractéristiques : un stade linéaire (stade I), un stade d’écoulement discontinu (stade II) et un stade stable (stade III). À la fin du stade I, plus de 90% des joints de grains β sont occupés par des joints de grains α (αGB). Le rendement discontinu du stade II provient de la fragmentation de αGB et de la formation intensive de dislocations mobiles près des joints de grains β. L'état d'équilibre du stade III résulte de deux modes de déformation. Pour ceux dont l'orientation d'activation est favorable pour leurs systèmes {110}ββ par rapport à la charge de compression, la déformation est réalisée par le glissement de dislocation et par la formation de bandes de glissement; alors que pour ceux avec leur {1"1" ̅"2" ̅}ββ systèmes - le système de transformation de β à α - dans des orientations favorables, la déformation est obtenue par formation intensive de précipités α intragranulaires
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Composite structure of α phase in metastable β Ti alloys induced by lattice strain during β to α phase transformation
Acta Materialia, 2017Co-Authors: Ke Hua, Yudong Zhang, Hongchao Kou, Weimin Gan, Jean-jacques Fundenberger, Claude EslingAbstract:Abstract The β to α phase transformation of Ti alloys progresses in a displacive-diffusive mixed-mode. The associated transformation strain has important influence on the resultant microstructure. In this work, the microstructural features of α precipitates in a metastable β Ti alloy, Ti-7333, were thoroughly investigated. Special attention was paid to the intragranular α for the advantage of a stress-free transformation environment. Results show that the constituents of each α precipitate is not single. Two kinds of nano-sized α domains exist. One is situated on the broad face of the major α precipitate (Named Interface α), and the other goes through the major α (termed penetrating α). The Interface α is related with the β matrix by the Burgers orientation relationship (BOR) and with the major α by a 60°/ 〈 11 2 ¯ 0 〉 α rotation. The nucleation of such α particles is induced by the largest shear strain generated by the formation of the major α. They act as stress-associated sympathetic nuclei of the neighboring α precipitates and eventually contribute to the formation of the triangular α cluster. The penetrating α does not obey the BOR with the β matrix but is related with the major α by a 60° rotation around another 〈 11 2 ¯ 0 〉 α axis. The nucleation of such α is induced by the largest normal strain generated by the formation of the main α plate. This work provides comprehensive information on the displacive characters of the β to α transformation and their impact on the microstructure of metastable β Ti alloys.
Aditya P. Mathur - One of the best experts on this subject based on the ideXlab platform.
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Interface Mutation Test Adequacy Criterion: An Empirical Evaluation
Empirical Software Engineering, 2001Co-Authors: Márcio Eduardo Delamaro, José Carlos Maldonado, Alberto Pasquini, Aditya P. MathurAbstract:An experiment was conducted to evaluate an inter-procedural test adequacy criterion Named Interface Mutation. Program SPACE , developed for the European Space Agency (ESA), was used in this experiment. The development record available for this program was used to find the faults uncovered during its development. Using this information the test process was reproduced starting with a version of SPACE containing several faults and then applying Interface Mutation. Thus we could evaluate the fault revealing effectiveness of Interface Mutation. Results from the experiment suggest that (a) the application of Interface Mutation favors the selection of fault revealing test cases when they exist and (b) Interface Mutation tends to select fault revealing test cases more efficiently than in the case where random selection is used.
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Interface Mutation: an approach for integration testing
IEEE Transactions on Software Engineering, 2001Co-Authors: Márcio Eduardo Delamaro, J.c. Maidonado, Aditya P. MathurAbstract:The need for test adequacy criteria is widely recognized. Several criteria have been proposed for the assessment of adequacy of tests at the unit level. However, there remains a lack of criteria for the assessment of the adequacy of tests generated during integration testing. We present a mutation based interprocedural criterion, Named Interface Mutation (IM), suitable for use during integration testing. A case study to evaluate the proposed criterion is reported. In the study, the UNIX sort utility was seeded with errors and Interface Mutation evaluated by measuring the cost of its application and its error revealing effectiveness. Alternative IM criteria using different sets of Interface Mutation operators were also evaluated. While comparing the error revealing effectiveness of these Interface Mutation-based test sets with same size randomly generated test sets, we observed that in most cases Interface Mutation based test sets are superior. The results suggest that Interface Mutation offers a viable test adequacy criteria for use at the integration level.
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ISSRE - Integration testing using Interface mutation
Proceedings of ISSRE '96: 7th International Symposium on Software Reliability Engineering, 1Co-Authors: Márcio Eduardo Delamaro, José Carlos Maldonado, Aditya P. MathurAbstract:A criterion for assessing the adequacy of test sets during integration testing is proposed. The criterion is based on a testing technique Named Interface Mutation. The technique itself is designed to be scalable with the size of the software under test; the size being measured in the number of subsystems integrated. Using Interface Mutation it is possible to assess the adequacy of tests incrementally while integrating various subsystems. Also reported are results from a pilot experiment conducted to study the cost and error defection effectiveness of Interface Mutation.
Márcio Eduardo Delamaro - One of the best experts on this subject based on the ideXlab platform.
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Interface Mutation Test Adequacy Criterion: An Empirical Evaluation
Empirical Software Engineering, 2001Co-Authors: Márcio Eduardo Delamaro, José Carlos Maldonado, Alberto Pasquini, Aditya P. MathurAbstract:An experiment was conducted to evaluate an inter-procedural test adequacy criterion Named Interface Mutation. Program SPACE , developed for the European Space Agency (ESA), was used in this experiment. The development record available for this program was used to find the faults uncovered during its development. Using this information the test process was reproduced starting with a version of SPACE containing several faults and then applying Interface Mutation. Thus we could evaluate the fault revealing effectiveness of Interface Mutation. Results from the experiment suggest that (a) the application of Interface Mutation favors the selection of fault revealing test cases when they exist and (b) Interface Mutation tends to select fault revealing test cases more efficiently than in the case where random selection is used.
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Interface Mutation: an approach for integration testing
IEEE Transactions on Software Engineering, 2001Co-Authors: Márcio Eduardo Delamaro, J.c. Maidonado, Aditya P. MathurAbstract:The need for test adequacy criteria is widely recognized. Several criteria have been proposed for the assessment of adequacy of tests at the unit level. However, there remains a lack of criteria for the assessment of the adequacy of tests generated during integration testing. We present a mutation based interprocedural criterion, Named Interface Mutation (IM), suitable for use during integration testing. A case study to evaluate the proposed criterion is reported. In the study, the UNIX sort utility was seeded with errors and Interface Mutation evaluated by measuring the cost of its application and its error revealing effectiveness. Alternative IM criteria using different sets of Interface Mutation operators were also evaluated. While comparing the error revealing effectiveness of these Interface Mutation-based test sets with same size randomly generated test sets, we observed that in most cases Interface Mutation based test sets are superior. The results suggest that Interface Mutation offers a viable test adequacy criteria for use at the integration level.
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ISSRE - Integration testing using Interface mutation
Proceedings of ISSRE '96: 7th International Symposium on Software Reliability Engineering, 1Co-Authors: Márcio Eduardo Delamaro, José Carlos Maldonado, Aditya P. MathurAbstract:A criterion for assessing the adequacy of test sets during integration testing is proposed. The criterion is based on a testing technique Named Interface Mutation. The technique itself is designed to be scalable with the size of the software under test; the size being measured in the number of subsystems integrated. Using Interface Mutation it is possible to assess the adequacy of tests incrementally while integrating various subsystems. Also reported are results from a pilot experiment conducted to study the cost and error defection effectiveness of Interface Mutation.
A.t.s. Chan - One of the best experts on this subject based on the ideXlab platform.
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MobiGATE: a mobile computing middleware for the active deployment of transport services
IEEE Transactions on Software Engineering, 2006Co-Authors: Yongjie Zheng, A.t.s. ChanAbstract:The use of gateway proxies is one important approach to facilitating adaptation across wireless and mobile environments. Importantly, augmented service entities deployed within the gateway proxy residing on the wired network can be composed and deployed to shield mobile clients from the effects of poor network characteristics. The usual approach to the static composition of service entities on the gateway proxy is to have these service entities interact with each other by explicitly invoking procedures on the Named Interface, but such a tight coupling of Interfaces inhibits the flexible composition and adaptation of the service entities to the dynamic operating characteristics of wireless networks. In this paper, we present a mobile gateway for the active deployment of transport entities or, for short, MobiGATE (pronounced Mobi-Gate). MobiGATE is a mobile middleware framework that supports the robust and flexible composition of transport entities, known as streamlets. The flow of data traffic is subjected to processing by a chain of streamlets. Each streamlet encapsulates a service entity that adapts the flow of traffic across the wireless network. To facilitate the dynamic reconfiguration of the streamlets, we advocate applying the concept of coordination as the unifying approach to composing these transport service entities. Importantly, MobiGATE delineates a clear separation of interdependent parts from the service-specific computational codes of those service entities. It does this by using a separate coordination language, called MobiGATE coordination language (MCL), to describe the coordination among streamlet service entities. The complete design, implementation, and evaluation of the MobiGATE system are presented in this paper. Initial experimental results validate the flexibility of the coordination approach in promoting separation-of-concern in the reconfiguration of services, while achieving low computation and delay overheads.
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ICPP - MobiGATE: a mobile gateway proxy for the active deployment of transport entities
2004Co-Authors: Yongjie Zheng, A.t.s. ChanAbstract:Using gateway proxies is one important approach to facilitating adaptation across wireless and mobile environments. Importantly, augmented service entities deployed within the gateway proxy residing on the wired network can be composed and deployed to shield mobile clients from the effects of poor network characteristics. The usual approach to the static composition of service entities on the gateway proxy is to have these service entities interact with each other by explicitly invoking procedures on the Named Interface. The tight coupling of Interfaces inhibits the flexible composition and adaptation of the service entities to the dynamic operating characteristics of wireless networks. We present a Mobile GATEway for the active deployment of transport entities or MobiGATE (pronounced as MobiGate) for short. MobiGATE is a mobile middleware framework that supports the robust and flexible composition of transport entities, known as streamlets. The flow of data traffic is subjected to processing by a chain of streamlets. Each streamlet encapsulates a service entity that serves to adapt the flow of traffic across the wireless network. To facilitate the dynamic reconfiguration of the streamlets, we advocate applying the concept of coordination as the unifying approach to composing these transport service entities. Importantly, MobiGATE delineates a clear separation of interdependency parts from the service-specific computational codes of those service entities by using a separate coordination language to describe the coordination among streamlet service entities. To this end, we have defined a compositional language called MobiGATE coordination language (MCL) that provides rich constructs to support the definition of compositions, with constrained type validation and checking.
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MobiGATE: a mobile gateway proxy for the active deployment of transport entities
International Conference on Parallel Processing 2004. ICPP 2004., 2004Co-Authors: Yongjie Zheng, A.t.s. ChanAbstract:Using gateway proxies is one important approach to facilitating adaptation across wireless and mobile environments. Importantly, augmented service entities deployed within the gateway proxy residing on the wired network can be composed and deployed to shield mobile clients from the effects of poor network characteristics. The usual approach to the static composition of service entities on the gateway proxy is to have these service entities interact with each other by explicitly invoking procedures on the Named Interface. The tight coupling of Interfaces inhibits the flexible composition and adaptation of the service entities to the dynamic operating characteristics of wireless networks. We present a Mobile GATEway for the active deployment of transport entities or MobiGATE (pronounced as MobiGate) for short. MobiGATE is a mobile middleware framework that supports the robust and flexible composition of transport entities, known as streamlets. The flow of data traffic is subjected to processing by a chain of streamlets. Each streamlet encapsulates a service entity that serves to adapt the flow of traffic across the wireless network. To facilitate the dynamic reconfiguration of the streamlets, we advocate applying the concept of coordination as the unifying approach to composing these transport service entities. Importantly, MobiGATE delineates a clear separation of interdependency parts from the service-specific computational codes of those service entities by using a separate coordination language to describe the coordination among streamlet service entities. To this end, we have defined a compositional language called MobiGATE coordination language (MCL) that provides rich constructs to support the definition of compositions, with constrained type validation and checking.Department of ComputingRefereed conference pape
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COMPSAC - Stream composition for highly adaptive and reconfigurable mobile middleware
Proceedings of the 28th Annual International Computer Software and Applications Conference 2004. COMPSAC 2004., 1Co-Authors: Yongjie Zheng, A.t.s. ChanAbstract:Using gateway proxies is one important approach to facilitating adaptation across wireless and mobile environments. Importantly, augmented service entities deployed within the gateway proxy residing on the wired network can be composed and deployed to shield mobile clients from the effects of poor network characteristics. The usual approach to the static composition of service entities on the gateway proxy is to have these service entities interact with each other by explicitly invoking procedures on the Named Interface. The tight coupling of Interfaces inhibits the flexible composition and adaptation of the service entities to the dynamic operating characteristics of wireless networks. In this paper, we present a Mobile GATEway for the Active deployment of Transport Entities or MobiGATE (pronounced as Mobi-Gate) for short. MobiGATE is a mobile middleware framework that supports the robust and flexible composition of transport entities, known as streamlets. The flow of data traffic is subjected to processing by a chain of streamlets. Each streamlet encapsulates a service entity that serves to adapt the flow of traffic across the wireless network. To facilitate the dynamic reconfiguration of the streamlets, we advocate applying the concept of coordination as the unifying approach to composing these transport service entities. Importantly, MobiGATE delineates a clear separation of interdependency parts from the service-specific computational codes of those service entities by using a separate coordination language to describe the coordination among streamlet service entities. To this end, we have defined a compositional language called MobiGATE Coordination Language (MCL) that provides rich constructs to support the definition of compositions, with constrained type validation and checking
Claude Esling - One of the best experts on this subject based on the ideXlab platform.
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Composite structure of α phase in metastable β Ti alloys induced by lattice strain during β to α phase transformation
Acta Materialia, 2017Co-Authors: Ke Hua, Yudong Zhang, Hongchao Kou, Weimin Gan, Jean-jacques Fundenberger, Claude EslingAbstract:Abstract The β to α phase transformation of Ti alloys progresses in a displacive-diffusive mixed-mode. The associated transformation strain has important influence on the resultant microstructure. In this work, the microstructural features of α precipitates in a metastable β Ti alloy, Ti-7333, were thoroughly investigated. Special attention was paid to the intragranular α for the advantage of a stress-free transformation environment. Results show that the constituents of each α precipitate is not single. Two kinds of nano-sized α domains exist. One is situated on the broad face of the major α precipitate (Named Interface α), and the other goes through the major α (termed penetrating α). The Interface α is related with the β matrix by the Burgers orientation relationship (BOR) and with the major α by a 60°/ 〈 11 2 ¯ 0 〉 α rotation. The nucleation of such α particles is induced by the largest shear strain generated by the formation of the major α. They act as stress-associated sympathetic nuclei of the neighboring α precipitates and eventually contribute to the formation of the triangular α cluster. The penetrating α does not obey the BOR with the β matrix but is related with the major α by a 60° rotation around another 〈 11 2 ¯ 0 〉 α axis. The nucleation of such α is induced by the largest normal strain generated by the formation of the main α plate. This work provides comprehensive information on the displacive characters of the β to α transformation and their impact on the microstructure of metastable β Ti alloys.
