The effects of Ni addition and aging treatment on the microstructure and properties of Cu?3Ti alloy were investigated. Themicrostructure and phase constituents were characterized by optical microscopy, scanning electr...The effects of Ni addition and aging treatment on the microstructure and properties of Cu?3Ti alloy were investigated. Themicrostructure and phase constituents were characterized by optical microscopy, scanning electron microscopy, X-ray diffractometerand high-resolution transmission electron microscopy, and the hardness and electrical conductivity were measured as well. Theresults show that NiTi phase forms with addition of Ni into as-cast Cu-3Ti alloy during solidification, and the as-cast microstructureevolves from dentrite to equiaxial structure. After aging treatment, coherent metastable β′-Cu4Ti precipitates from the Cu matrix.However, β′-Cu4Ti precipitation phase transforms into equilibrium, incoherent and lamellar Cu3Ti phase after overaging. Meanwhile,aging treatment results in appearance of annealing twins in the residual NiTi phase, and dislocation lines exist in the Cu matrix. Niaddition enhances the electrical conductivity, but decreases the hardness of Cu?3Ti alloy. In the range of experiments, the optimumaging treatment for Cu?3Ti?1Ni alloy is 300 °C for 2 h and 450 °C for 7 h. The hardness and electrical conductivity were HV 205and 18.2%IACS (international annealed copper standard), respectively.展开更多
To disclose the effect of contact force and electrode gap on the material transfer behavior of Ag-based contact material, arc-erosion tests of the Ag-4wt.%TiB2 contact material were performed for 5000 operations at 24...To disclose the effect of contact force and electrode gap on the material transfer behavior of Ag-based contact material, arc-erosion tests of the Ag-4wt.%TiB2 contact material were performed for 5000 operations at 24 V/16 A under resistive load on an electric contact material testing system. The arc energy and arc duration were investigated, the surface morphologies of eroded anode and cathode were characterized, the mass changes after arc-erosion tests were determined, and the material transfer behavior was discussed as well. The results show that contact force has a significant effect on the arc energy, arc duration and erosion morphology, but has no impact on the material transfer mode. However, electrode gap not only influences the arc energy, arc duration and surface morphology, but also changes the material transfer mode. At 1 mm, the material transfers from anode to cathode. Nevertheless, an opposite mode presents at 4 mm, which is from cathode to anode.展开更多
基金Projects(51201132,51274163) supported by the National Natural Science Foundation of ChinaProject(13JS076) supported by Shaanxi Provincial Key Laboratory Research Program,ChinaProject(2011HBSZS009) supported by Shaanxi Provincial Project of Special Foundation of Key Disciplines,China
文摘The effects of Ni addition and aging treatment on the microstructure and properties of Cu?3Ti alloy were investigated. Themicrostructure and phase constituents were characterized by optical microscopy, scanning electron microscopy, X-ray diffractometerand high-resolution transmission electron microscopy, and the hardness and electrical conductivity were measured as well. Theresults show that NiTi phase forms with addition of Ni into as-cast Cu-3Ti alloy during solidification, and the as-cast microstructureevolves from dentrite to equiaxial structure. After aging treatment, coherent metastable β′-Cu4Ti precipitates from the Cu matrix.However, β′-Cu4Ti precipitation phase transforms into equilibrium, incoherent and lamellar Cu3Ti phase after overaging. Meanwhile,aging treatment results in appearance of annealing twins in the residual NiTi phase, and dislocation lines exist in the Cu matrix. Niaddition enhances the electrical conductivity, but decreases the hardness of Cu?3Ti alloy. In the range of experiments, the optimumaging treatment for Cu?3Ti?1Ni alloy is 300 °C for 2 h and 450 °C for 7 h. The hardness and electrical conductivity were HV 205and 18.2%IACS (international annealed copper standard), respectively.
基金Projects(51274163,51605146) supported by the National Natural Science Foundation of ChinaProject(U1502274) supported by Key Program of the National Natural Science Foundation of China+2 种基金Project(2018M632769) supported by the China Postdoctoral Science FoundationProject(2017SKY-WK010) supported by the Research Fund of Shaanxi Key Laboratory of Comprehensive Utilization of Tailings Resources,ChinaProject(18JK0722) supported by Special Research Program of Shaanxi Provincial Department of Education,China
文摘To disclose the effect of contact force and electrode gap on the material transfer behavior of Ag-based contact material, arc-erosion tests of the Ag-4wt.%TiB2 contact material were performed for 5000 operations at 24 V/16 A under resistive load on an electric contact material testing system. The arc energy and arc duration were investigated, the surface morphologies of eroded anode and cathode were characterized, the mass changes after arc-erosion tests were determined, and the material transfer behavior was discussed as well. The results show that contact force has a significant effect on the arc energy, arc duration and erosion morphology, but has no impact on the material transfer mode. However, electrode gap not only influences the arc energy, arc duration and surface morphology, but also changes the material transfer mode. At 1 mm, the material transfers from anode to cathode. Nevertheless, an opposite mode presents at 4 mm, which is from cathode to anode.
基金National Key R&D Program of China(2017YFE0301402)Shaanxi Provincial Project of Special Foundation of Key Disciplines(2018ZDXM-GY-136,2019JM-595,15JF025)。
基金National Natural Science Foundation of China(51601143)International Collaboration Program of Science and Technology Department of Shaanxi(2017KW-021)+1 种基金Key Laboratory Research Program of Shaanxi Educational Department(17JS082)Opening Foundation of National United Engineering Laboratory for Advanced Bearing Tribology of Henan University of Science and Technology(201801)。
