Enhanced Fatigue Resistance of Nanocrystalline Ni<sub>50.8</sub>Ti<sub>49.2</sub> Wires by Mechanical Training
In this paper, the fatigue resistance of superelastic NiTi shape memory alloy (SMA) wires was improved by combining mechanical training and nanocrystallization. Fatigue tests were performed after mechanical training with a peak stress of 600 MPa for 60 cycles of nanocrystalline (NC) NiTi wires, and...
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MDPI AG
2023-02-01
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| Series: | Metals |
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| Online Access: | https://www.mdpi.com/2075-4701/13/2/361 |
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| author | Peng Chen Xiaorong Cai Na Min Yunfan Liu Zhengxiong Wang Mingjiang Jin Xuejun Jin |
| author_facet | Peng Chen Xiaorong Cai Na Min Yunfan Liu Zhengxiong Wang Mingjiang Jin Xuejun Jin |
| author_sort | Peng Chen |
| collection | DOAJ |
| description | In this paper, the fatigue resistance of superelastic NiTi shape memory alloy (SMA) wires was improved by combining mechanical training and nanocrystallization. Fatigue tests were performed after mechanical training with a peak stress of 600 MPa for 60 cycles of nanocrystalline (NC) NiTi wires, and the associated microscopic mechanism was investigated by using transmission electron microscopy (TEM) and transmission Kikuchi diffraction (TKD). The results showed that stress-controlled training effectively improved the functional stability (the accumulated residual strain decreased by 83.8% in the first 5000 cycles) of NC NiTi SMA wires, as well as increased the average structural fatigue life by 187.4% (from 4538 cycles to 13,040 cycles). TEM observations and TKD results revealed that training-induced dislocations resulted in lattice rotation and preferential grain orientation. The finite element method (FEM) simulation results indicated that the training-induced preferential grain orientation tended to decrease the local stress concentration and strain energy density. Combined with fractography analysis, the uniform deformation caused by mechanical training changed the crack growth mode from multi-regional propagation to single-regional propagation, improving the structural fatigue life. |
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| institution | Directory Open Access Journal |
| issn | 2075-4701 |
| language | English |
| last_indexed | 2024-03-11T08:25:05Z |
| publishDate | 2023-02-01 |
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| series | Metals |
| spelling | doaj.art-56521ba0ee77426e97db7d7155723f922023-11-16T22:08:14ZengMDPI AGMetals2075-47012023-02-0113236110.3390/met13020361Enhanced Fatigue Resistance of Nanocrystalline Ni<sub>50.8</sub>Ti<sub>49.2</sub> Wires by Mechanical TrainingPeng Chen0Xiaorong Cai1Na Min2Yunfan Liu3Zhengxiong Wang4Mingjiang Jin5Xuejun Jin6Institute of Phase Transformation and Complex Microstructure, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, ChinaInstitute of Phase Transformation and Complex Microstructure, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, ChinaKey Laboratory for Microstructures, Shanghai University, Shanghai 200444, ChinaInstitute of Forming Technology and Equipment, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200030, ChinaInstitute of Phase Transformation and Complex Microstructure, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, ChinaInstitute of Phase Transformation and Complex Microstructure, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, ChinaInstitute of Phase Transformation and Complex Microstructure, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, ChinaIn this paper, the fatigue resistance of superelastic NiTi shape memory alloy (SMA) wires was improved by combining mechanical training and nanocrystallization. Fatigue tests were performed after mechanical training with a peak stress of 600 MPa for 60 cycles of nanocrystalline (NC) NiTi wires, and the associated microscopic mechanism was investigated by using transmission electron microscopy (TEM) and transmission Kikuchi diffraction (TKD). The results showed that stress-controlled training effectively improved the functional stability (the accumulated residual strain decreased by 83.8% in the first 5000 cycles) of NC NiTi SMA wires, as well as increased the average structural fatigue life by 187.4% (from 4538 cycles to 13,040 cycles). TEM observations and TKD results revealed that training-induced dislocations resulted in lattice rotation and preferential grain orientation. The finite element method (FEM) simulation results indicated that the training-induced preferential grain orientation tended to decrease the local stress concentration and strain energy density. Combined with fractography analysis, the uniform deformation caused by mechanical training changed the crack growth mode from multi-regional propagation to single-regional propagation, improving the structural fatigue life.https://www.mdpi.com/2075-4701/13/2/361shape memory alloysnanocrystalline materialsfatiguemechanical trainingtransmission Kikuchi diffraction |
| spellingShingle | Peng Chen Xiaorong Cai Na Min Yunfan Liu Zhengxiong Wang Mingjiang Jin Xuejun Jin Enhanced Fatigue Resistance of Nanocrystalline Ni<sub>50.8</sub>Ti<sub>49.2</sub> Wires by Mechanical Training Metals shape memory alloys nanocrystalline materials fatigue mechanical training transmission Kikuchi diffraction |
| title | Enhanced Fatigue Resistance of Nanocrystalline Ni<sub>50.8</sub>Ti<sub>49.2</sub> Wires by Mechanical Training |
| title_full | Enhanced Fatigue Resistance of Nanocrystalline Ni<sub>50.8</sub>Ti<sub>49.2</sub> Wires by Mechanical Training |
| title_fullStr | Enhanced Fatigue Resistance of Nanocrystalline Ni<sub>50.8</sub>Ti<sub>49.2</sub> Wires by Mechanical Training |
| title_full_unstemmed | Enhanced Fatigue Resistance of Nanocrystalline Ni<sub>50.8</sub>Ti<sub>49.2</sub> Wires by Mechanical Training |
| title_short | Enhanced Fatigue Resistance of Nanocrystalline Ni<sub>50.8</sub>Ti<sub>49.2</sub> Wires by Mechanical Training |
| title_sort | enhanced fatigue resistance of nanocrystalline ni sub 50 8 sub ti sub 49 2 sub wires by mechanical training |
| topic | shape memory alloys nanocrystalline materials fatigue mechanical training transmission Kikuchi diffraction |
| url | https://www.mdpi.com/2075-4701/13/2/361 |
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