Cu–Nb microcomposite wire was successfully prepared by a groove rolling process.The effects of groove rolling on the diffraction peaks,microstructure,and properties of the Cu–Nb microcomposite were investigated and ...Cu–Nb microcomposite wire was successfully prepared by a groove rolling process.The effects of groove rolling on the diffraction peaks,microstructure,and properties of the Cu–Nb microcomposite were investigated and the microstructure evolutions and strengthening mechanism were discussed.The tensile strength of the Cu–Nb microcomposite wire with a diameter of 2.02 mm was greater than 1 GPa,and its conductivity reached 68%of the International Annealed Copper Standard,demonstrating the Cu–Nb microcomposite wire with high tensile strength and high conductivity after groove rolling.The results show that an appropriate groove rolling method can improve the performance of the Cu–Nb microcomposite wire.展开更多
NiTiCu-based shape memory alloys have been considered as ideal materials for solid-state refrigeration due to their superb cycling stability for elastocaloric effect.However,the embrittlement and deterioration caused ...NiTiCu-based shape memory alloys have been considered as ideal materials for solid-state refrigeration due to their superb cycling stability for elastocaloric effect.However,the embrittlement and deterioration caused by secondary phase and coarse grains restrict their applications,and it is still challenging since the geometric components are required.Here,bulk NiTiCuCo parts with excellent forming quality were fabricated by laser powder bed fusion(LPBF)technique.The as-fabricated alloy exhibits refined three-phases hierarchical microcomposite formed based on the rapid cooling mode of LPBF,composed of intricate dendritic Ti2Ni–NiTi composite and nano Ti2Cu embedded inside the NiTi-matrix.This configuration endows far superior elastocaloric stability compared to the as-cast counterpart.The low fatigue stems from the strong elastic coupling between the interphases with reversible martensite transformation,revealed by in-situ synchrotron high-energy x-ray diffraction.The fabrication of NiTiCuCo alloy via LPBF fills the bill of complex geometric structures for elastocaloric NiTiCu alloys.The understanding of interphase micro-coupling could provide the guide for designing LPBF fabricated shape memory-based composites,enabling their applications for special demands on other functionalities.展开更多
The effects of annealing on microstructure, posite wire have been investigated. Neither changes in magnetoresistance, and hardness of an in situ Cu-Nb microcom- microstructure nor hardness were found until 500 ℃. Par...The effects of annealing on microstructure, posite wire have been investigated. Neither changes in magnetoresistance, and hardness of an in situ Cu-Nb microcom- microstructure nor hardness were found until 500 ℃. Particularly, microstructural change within the Nb films was observed in the annealed samples. The room-temperature magnetoresistivity was almost negligible, while magnetoresistivity at -196℃increased with magnetic field. At temperature above 500 ℃, recovery and recrystallization occurred, and both the resistance and hardness decreased.展开更多
基金This work was financially supported by the National Key R&D Program of China(No.2016YFA0401701)the National Natural Science Foundation of China(No.51601151).
文摘Cu–Nb microcomposite wire was successfully prepared by a groove rolling process.The effects of groove rolling on the diffraction peaks,microstructure,and properties of the Cu–Nb microcomposite were investigated and the microstructure evolutions and strengthening mechanism were discussed.The tensile strength of the Cu–Nb microcomposite wire with a diameter of 2.02 mm was greater than 1 GPa,and its conductivity reached 68%of the International Annealed Copper Standard,demonstrating the Cu–Nb microcomposite wire with high tensile strength and high conductivity after groove rolling.The results show that an appropriate groove rolling method can improve the performance of the Cu–Nb microcomposite wire.
基金supported by National Key R&D Program of China (2022YFB4600500)the National Safety Academic Fund (U2130201 and U2330105)the NSFC (52201214and 51971244)
文摘NiTiCu-based shape memory alloys have been considered as ideal materials for solid-state refrigeration due to their superb cycling stability for elastocaloric effect.However,the embrittlement and deterioration caused by secondary phase and coarse grains restrict their applications,and it is still challenging since the geometric components are required.Here,bulk NiTiCuCo parts with excellent forming quality were fabricated by laser powder bed fusion(LPBF)technique.The as-fabricated alloy exhibits refined three-phases hierarchical microcomposite formed based on the rapid cooling mode of LPBF,composed of intricate dendritic Ti2Ni–NiTi composite and nano Ti2Cu embedded inside the NiTi-matrix.This configuration endows far superior elastocaloric stability compared to the as-cast counterpart.The low fatigue stems from the strong elastic coupling between the interphases with reversible martensite transformation,revealed by in-situ synchrotron high-energy x-ray diffraction.The fabrication of NiTiCuCo alloy via LPBF fills the bill of complex geometric structures for elastocaloric NiTiCu alloys.The understanding of interphase micro-coupling could provide the guide for designing LPBF fabricated shape memory-based composites,enabling their applications for special demands on other functionalities.
基金funded by the National Natural Science Foundation of China(Grant Nos.51421001 and 51301040)the Natural Science Foundation of Fujian Province of China(No.2016J05119)+1 种基金the Science and Technology Fund from Fujian Education Department of China(Grant No.JA15072)supported by US National Science Foundation Cooperative Agreement No.DMR-1157490
文摘The effects of annealing on microstructure, posite wire have been investigated. Neither changes in magnetoresistance, and hardness of an in situ Cu-Nb microcom- microstructure nor hardness were found until 500 ℃. Particularly, microstructural change within the Nb films was observed in the annealed samples. The room-temperature magnetoresistivity was almost negligible, while magnetoresistivity at -196℃increased with magnetic field. At temperature above 500 ℃, recovery and recrystallization occurred, and both the resistance and hardness decreased.
