In this work,the underlying mechanism responsible for the near-linear elastic deformation behavior of a dual-phase Ti-Nb alloy consisting of β and α'' phase with large recoverable strain was systematically e...In this work,the underlying mechanism responsible for the near-linear elastic deformation behavior of a dual-phase Ti-Nb alloy consisting of β and α'' phase with large recoverable strain was systematically elucidated.Based on in situ synchrotron X-ray diffraction(SXRD)analyses,it was found that besides intrinsic elastic deformation,a slight reversible β-α'' stress-induced martensitic(SIM)transformation,which proceeded in a consecutive mode under the retarding effect of micro-defects,took place during the near-linear elastic deformation.After unloading,a small amount of residual macroscopic strain remained in the specimen due to the incomplete reverse α''→β transformation on unloading.The high near-linear elastic deformability of the cold drawing(CD)Ti-Nb alloy has been revealed to be attributed to the coupling actions of intrinsic elasticity as well as the consecutive and reversible β-α'' SIM transformation.Our research may contribute to a new avenue for the design and development of novel dual-phase Ti-based alloys with desirable elastic deformability.展开更多
Shape memory alloys(SMAs)are smart materials with superelasticity originating from a reversible stressinduced martensitic transformation(MT)accompanied by a significant electrical resistance change.However,the stress-...Shape memory alloys(SMAs)are smart materials with superelasticity originating from a reversible stressinduced martensitic transformation(MT)accompanied by a significant electrical resistance change.However,the stress-strain and resistance-stress relationships of typical NiTi wires are non-linear due to the stress plateau during the stress-induced MT.This limits the usage of these materials as pressure sensors.Herein,we propose a high-strength flexible sensor based on superelastic NiTi wires that achieves near-linear mechanical and electrical responses through a low-cost double-braided strategy.This microarchitectured strategy reduces or even eliminates stress plateau and it is demonstrated that the phase transformation of microfilaments can be controlled:regions with localized stress undergo the MT first,which is successively followed by the rest of the microfilament.This structure-dependent MT characteristic exhibits slim-hysteresis superelasticity and tunable low stiffness,and the braided wire shows improved flexibility.The double-braided NiTi microfilaments exhibit stable electrical properties and repeatability under approximately 600 MPa(8%strain)and can maintain stability over a wide temperature range(303-403 K).Moreover,a cross-grid flexible woven sensor array textile based on microfilaments is further developed to detect pressure distribution.This work provides insight into the design and application of SMAs in the field of flexible and functional fiber.展开更多
基金financially supported by the National Natural Science Foundation of China(No.52175410)the Six Talent Peaks Project in Jiangsu Province(No.2019-XCL-113)+1 种基金Zhenjiang Science&Technology Program(No.GY2020001)the Project of Faculty of Agricultural Equipment of Jiangsu University(No.NZXB20200101)。
文摘In this work,the underlying mechanism responsible for the near-linear elastic deformation behavior of a dual-phase Ti-Nb alloy consisting of β and α'' phase with large recoverable strain was systematically elucidated.Based on in situ synchrotron X-ray diffraction(SXRD)analyses,it was found that besides intrinsic elastic deformation,a slight reversible β-α'' stress-induced martensitic(SIM)transformation,which proceeded in a consecutive mode under the retarding effect of micro-defects,took place during the near-linear elastic deformation.After unloading,a small amount of residual macroscopic strain remained in the specimen due to the incomplete reverse α''→β transformation on unloading.The high near-linear elastic deformability of the cold drawing(CD)Ti-Nb alloy has been revealed to be attributed to the coupling actions of intrinsic elasticity as well as the consecutive and reversible β-α'' SIM transformation.Our research may contribute to a new avenue for the design and development of novel dual-phase Ti-based alloys with desirable elastic deformability.
基金supported by the National Natural Science Foundation of China(Nos.52031005,52201224)the Natural Science Foundation of Shanghai(No.24ZR1438200)+1 种基金the Shanghai Academy of Spaceflight Technology Joint Research Fund(No.USCAST2023-19)the Equipment Development Depart-ment Huiyan Action.
文摘Shape memory alloys(SMAs)are smart materials with superelasticity originating from a reversible stressinduced martensitic transformation(MT)accompanied by a significant electrical resistance change.However,the stress-strain and resistance-stress relationships of typical NiTi wires are non-linear due to the stress plateau during the stress-induced MT.This limits the usage of these materials as pressure sensors.Herein,we propose a high-strength flexible sensor based on superelastic NiTi wires that achieves near-linear mechanical and electrical responses through a low-cost double-braided strategy.This microarchitectured strategy reduces or even eliminates stress plateau and it is demonstrated that the phase transformation of microfilaments can be controlled:regions with localized stress undergo the MT first,which is successively followed by the rest of the microfilament.This structure-dependent MT characteristic exhibits slim-hysteresis superelasticity and tunable low stiffness,and the braided wire shows improved flexibility.The double-braided NiTi microfilaments exhibit stable electrical properties and repeatability under approximately 600 MPa(8%strain)and can maintain stability over a wide temperature range(303-403 K).Moreover,a cross-grid flexible woven sensor array textile based on microfilaments is further developed to detect pressure distribution.This work provides insight into the design and application of SMAs in the field of flexible and functional fiber.
