Shape Memory

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L C Zhao - One of the best experts on this subject based on the ideXlab platform.

  • Shape-Memory behaviors in an aged Ni-rich TiNiHf high temperature Shape-Memory alloy
    Intermetallics, 2008
    Co-Authors: X.l. Meng, Y.d. Fu, Q.f. Li, Junzheng Zhang, W. Cai, L C Zhao
    Abstract:

    Abstract The Shape-Memory behaviors including both one-way and two-way Shape-Memory effects were investigated in a Ni-rich Ti 29.4 Ni 50.6 Hf 20 alloy aged at 823 K for different hours. The precipitation of (Ti,Hf) 3 Ni 4 particles strengthens the matrix strongly after the proper aging process, which should be responsible for the improvement of the Shape-Memory properties. Both one-way and two-way Shape-Memory strain increase rapidly with prolonging the aging time at the beginning of aging and then decrease with further increasing the aging time. The precipitates strengthen the matrix so that dislocations are hard to be introduced during the thermal cycling, resulting in the increase of the stability of the two-way Shape-Memory effect in the aged Ni-rich TiNiHf alloy. Therefore, it is feasible to use Ni-rich TiNiHf alloy as high temperature Shape-Memory alloy (SMA) through aging because the phase transformation temperatures are increased greatly to a high level and the Shape-Memory properties are also improved.

  • Two-way Shape Memory effect of a TiNiHf high temperature Shape Memory alloy
    Journal of Alloys and Compounds, 2004
    Co-Authors: X.l. Meng, W. Cai, Yufeng Zheng, L C Zhao
    Abstract:

    The two-way Shape Memory effect in a Ti36Ni49Hf15 high temperature Shape Memory alloy (SMA) has been systematically studied by bending tests. In the TiNiHf alloy, the martensite deformation is an effective method to get two-way Shape Memory effect even with a small deformation strain. When the TiNiHf alloy is deformed at a full martensite state, the deformation mechanism is the martensite orientation accompanied by the dislocation slip. The experimental results indicated that the internal stress field formed by the bending deformation is in the directions of the preferentially oriented martensite variants formed during the bending deformation. Upon cooling the preferentially oriented martensite variants form under such an oriented stress field, which should be responsible for the generation of the two-way Shape Memory effect. Proper training process and aging benefit the formation of the oriented stress field, resulting in the improvement of the two-way Shape Memory effect. When the training strain is 7.1% and the training temperature is room temperature, a two-way Shape Memory strain of 0.88% is obtained in the Ti36Ni49Hf15 alloy. This value is the maximum two-way Shape Memory strain in the TiNi-based high temperature SMAs so far. In comparison with the TiNi alloy, the TiNiHf high temperature SMA shows the two-way Shape Memory effect with the relative poor stability due to the lower strength of martensite. © 2003 Elsevier B.V. All rights reserved.

  • Shape Memory properties of the Ti36Ni49Hf15 high temperature Shape Memory alloy
    Materials Letters, 2000
    Co-Authors: Xianglong Meng, Z Wang, Yufeng Zheng, L C Zhao
    Abstract:

    Abstract The Shape Memory properties have been studied in a Ti 36 Ni 49 Hf 15 high temperature Shape Memory alloy (SMA) by bending tests. The Shape Memory effect (SME) of the alloy is closely related to the deformation condition. It shows about 3% completely reversible strain when the TiNiHf alloy is deformed at the room temperature. The Shape recovery ratio is constant at 92% when the deformation temperature is below 457 K, then rapidly decreases to zero above 590 K for the specimen deformed to 4.5%. Obvious two-way Shape Memory effect (TWSME) is obtained in the Ti 36 Ni 49 Hf 15 alloy aged at 973 K for various hours. As the aging time further increases, the TWSME decreases. Moreover, TWSME in the aged Ti 36 Ni 49 Hf 15 alloy is unstable and decreases rapidly after several thermal cycles.

Shuichi Miyazaki - One of the best experts on this subject based on the ideXlab platform.

  • Shape-Memory materials and hybrid composites for smart systems: Part I Shape-Memory materials
    Journal of Materials Science, 1998
    Co-Authors: Z G Wei, R. Sandstroröm, R. Sandstroröm, Rolf Sandström, Shuichi Miyazaki
    Abstract:

    A review is presented of the current research and development of Shape-Memory materials, including Shape-Memory alloys, Shape-Memory ceramics and Shape-Memory polymers. The Shape-Memory materials exhibit some novel performances, such as sensoring (thermal, stress or field), large-stroke actuation, high damping, adaptive responses, Shape Memory and superelasticity capability, which can be utilized in various engineering approaches to smart systems. Based on an extensive literature survey, the various Shape-Memory materials are outlined, with special attention to the recently developed or emerged materials. The basic phenomena in the materials, that is, the stimulus-induced phase transformations which result in the unique performance and govern the remarkable changes in properties of the materials, are systematically lineated. The remaining technical barriers, and the challenges to improve the present materials system and develop a new Shape Memory materials are discussed.

  • Shape Memory materials and hybrid composites for smart systems: Part II Shape-Memory hybrid composites
    Journal of Materials Science, 1998
    Co-Authors: Z G Wei, R. Sandstroröm, Shuichi Miyazaki, Rolf Sandström
    Abstract:

    By hybridizing or incorporating Shape-Memory materials with other functional materials or structural materials, smart composites can be fabricated which may utilize the unique functions or properties of the individual bulk materials to achieve multiple responses and optimal properties, or, to tune their properties to adapt to environmental changes. A variety of Shape-Memory hybrid composites have been designed and manufactured, with Shape-Memory elements being either the matrix or the reinforcement. The hybrid composites provide tremendous potential for creating new paradigms for material–structural interactions and demonstrate varying success in many engineering applications. This review, from the standpoint of materials science, will give a state-of-the-art survey on the various Shape-Memory hybrid smart composites developed during the last decade. Emphasis is placed on the design, fabrication, characterization and performance of fibre-reinforced, particle-reinforced and multi-layered thin-film Shape-Memory composites.

  • Review Shape-Memory materials and hybrid composites for smart systems Part I Shape-Memory materials
    1998
    Co-Authors: Z G Wei, Shuichi Miyazaki
    Abstract:

    A review is presented of the current research and development of Shape-Memory materials, including Shape-Memory alloys, Shape-Memory ceramics and Shape-Memory polymers. The Shape-Memorymaterials exhibit some novel performances,such as sensoring (thermal, stress or field), large-stroke actuation, high damping, adaptive responses, Shape Memory and superelasticity capability, which can be utilized in various engineering approaches to smart systems. Based on an extensive literature survey, the various Shape-Memory materials are outlined, with special attention to the recently developed or emerged materials. The basic phenomena in the materials, that is, the stimulus-induced phase transformationswhich result in the unique performanceand govern the remarkablechanges in properties of the materials, are systematically lineated. The remaining technical barriers, and the challenges to improve the present materials system and develop a new Shape Memory materials are discussed. a 1998 Kluwer Academic Publishers

Hani E. Naguib - One of the best experts on this subject based on the ideXlab platform.

X.l. Meng - One of the best experts on this subject based on the ideXlab platform.

  • Shape-Memory behaviors in an aged Ni-rich TiNiHf high temperature Shape-Memory alloy
    Intermetallics, 2008
    Co-Authors: X.l. Meng, Y.d. Fu, Q.f. Li, Junzheng Zhang, W. Cai, L C Zhao
    Abstract:

    Abstract The Shape-Memory behaviors including both one-way and two-way Shape-Memory effects were investigated in a Ni-rich Ti 29.4 Ni 50.6 Hf 20 alloy aged at 823 K for different hours. The precipitation of (Ti,Hf) 3 Ni 4 particles strengthens the matrix strongly after the proper aging process, which should be responsible for the improvement of the Shape-Memory properties. Both one-way and two-way Shape-Memory strain increase rapidly with prolonging the aging time at the beginning of aging and then decrease with further increasing the aging time. The precipitates strengthen the matrix so that dislocations are hard to be introduced during the thermal cycling, resulting in the increase of the stability of the two-way Shape-Memory effect in the aged Ni-rich TiNiHf alloy. Therefore, it is feasible to use Ni-rich TiNiHf alloy as high temperature Shape-Memory alloy (SMA) through aging because the phase transformation temperatures are increased greatly to a high level and the Shape-Memory properties are also improved.

  • Two-way Shape Memory effect of a TiNiHf high temperature Shape Memory alloy
    Journal of Alloys and Compounds, 2004
    Co-Authors: X.l. Meng, W. Cai, Yufeng Zheng, L C Zhao
    Abstract:

    The two-way Shape Memory effect in a Ti36Ni49Hf15 high temperature Shape Memory alloy (SMA) has been systematically studied by bending tests. In the TiNiHf alloy, the martensite deformation is an effective method to get two-way Shape Memory effect even with a small deformation strain. When the TiNiHf alloy is deformed at a full martensite state, the deformation mechanism is the martensite orientation accompanied by the dislocation slip. The experimental results indicated that the internal stress field formed by the bending deformation is in the directions of the preferentially oriented martensite variants formed during the bending deformation. Upon cooling the preferentially oriented martensite variants form under such an oriented stress field, which should be responsible for the generation of the two-way Shape Memory effect. Proper training process and aging benefit the formation of the oriented stress field, resulting in the improvement of the two-way Shape Memory effect. When the training strain is 7.1% and the training temperature is room temperature, a two-way Shape Memory strain of 0.88% is obtained in the Ti36Ni49Hf15 alloy. This value is the maximum two-way Shape Memory strain in the TiNi-based high temperature SMAs so far. In comparison with the TiNi alloy, the TiNiHf high temperature SMA shows the two-way Shape Memory effect with the relative poor stability due to the lower strength of martensite. © 2003 Elsevier B.V. All rights reserved.

Z G Wei - One of the best experts on this subject based on the ideXlab platform.

  • Shape-Memory materials and hybrid composites for smart systems: Part I Shape-Memory materials
    Journal of Materials Science, 1998
    Co-Authors: Z G Wei, R. Sandstroröm, R. Sandstroröm, Rolf Sandström, Shuichi Miyazaki
    Abstract:

    A review is presented of the current research and development of Shape-Memory materials, including Shape-Memory alloys, Shape-Memory ceramics and Shape-Memory polymers. The Shape-Memory materials exhibit some novel performances, such as sensoring (thermal, stress or field), large-stroke actuation, high damping, adaptive responses, Shape Memory and superelasticity capability, which can be utilized in various engineering approaches to smart systems. Based on an extensive literature survey, the various Shape-Memory materials are outlined, with special attention to the recently developed or emerged materials. The basic phenomena in the materials, that is, the stimulus-induced phase transformations which result in the unique performance and govern the remarkable changes in properties of the materials, are systematically lineated. The remaining technical barriers, and the challenges to improve the present materials system and develop a new Shape Memory materials are discussed.

  • Shape Memory materials and hybrid composites for smart systems: Part II Shape-Memory hybrid composites
    Journal of Materials Science, 1998
    Co-Authors: Z G Wei, R. Sandstroröm, Shuichi Miyazaki, Rolf Sandström
    Abstract:

    By hybridizing or incorporating Shape-Memory materials with other functional materials or structural materials, smart composites can be fabricated which may utilize the unique functions or properties of the individual bulk materials to achieve multiple responses and optimal properties, or, to tune their properties to adapt to environmental changes. A variety of Shape-Memory hybrid composites have been designed and manufactured, with Shape-Memory elements being either the matrix or the reinforcement. The hybrid composites provide tremendous potential for creating new paradigms for material–structural interactions and demonstrate varying success in many engineering applications. This review, from the standpoint of materials science, will give a state-of-the-art survey on the various Shape-Memory hybrid smart composites developed during the last decade. Emphasis is placed on the design, fabrication, characterization and performance of fibre-reinforced, particle-reinforced and multi-layered thin-film Shape-Memory composites.

  • Review Shape-Memory materials and hybrid composites for smart systems Part I Shape-Memory materials
    1998
    Co-Authors: Z G Wei, Shuichi Miyazaki
    Abstract:

    A review is presented of the current research and development of Shape-Memory materials, including Shape-Memory alloys, Shape-Memory ceramics and Shape-Memory polymers. The Shape-Memorymaterials exhibit some novel performances,such as sensoring (thermal, stress or field), large-stroke actuation, high damping, adaptive responses, Shape Memory and superelasticity capability, which can be utilized in various engineering approaches to smart systems. Based on an extensive literature survey, the various Shape-Memory materials are outlined, with special attention to the recently developed or emerged materials. The basic phenomena in the materials, that is, the stimulus-induced phase transformationswhich result in the unique performanceand govern the remarkablechanges in properties of the materials, are systematically lineated. The remaining technical barriers, and the challenges to improve the present materials system and develop a new Shape Memory materials are discussed. a 1998 Kluwer Academic Publishers

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