By means of the measurement of mechnical properties and resistivity and X-ray diffraction and transmission microscopy,the effect of cold deformation on the kinetics of spinodal decomposition of Cu-9Ni-6Sn-0.3Ce alloy ...By means of the measurement of mechnical properties and resistivity and X-ray diffraction and transmission microscopy,the effect of cold deformation on the kinetics of spinodal decomposition of Cu-9Ni-6Sn-0.3Ce alloy was studied.The strengthening process of the cold-worked and aged alloy was found to be accelerated.Using the theory of dislocation,the strengthening in cold-worked alloy can be attributed to the acceleration of spinodal process.展开更多
By measurement of mechanical and electrical properties,modulation wavelength,TEM techniques,etc.,the effect of Y on the spinodal decomposition in a Cu-9Ni-6Sn alloy has been studied.The results show that Y can acceler...By measurement of mechanical and electrical properties,modulation wavelength,TEM techniques,etc.,the effect of Y on the spinodal decomposition in a Cu-9Ni-6Sn alloy has been studied.The results show that Y can accelerate spinodal decomposition in the alloy,hinder the growth of celluoid structurers occurring at grain boundaries,and improve the combination of strength and plasticity.展开更多
Effect of Si and Ti on dynamic recrystallization(DRX)of Cu-15Ni-8 Sn alloy was studied using hot compression tests over deformation temperature range of 750-950℃and strain rate range of 0.001-10 s^-1.The results show...Effect of Si and Ti on dynamic recrystallization(DRX)of Cu-15Ni-8 Sn alloy was studied using hot compression tests over deformation temperature range of 750-950℃and strain rate range of 0.001-10 s^-1.The results show that the dynamic recrystallization behavior during hot deformation is significantly affected by the trace elements of Si and Ti.The addition of Si and Ti promotes the formation of Ni16Si7Ti6 particles during hot deformation,which promotes the nucleation of dynamic recrystallization by accelerating the transition from low-angle boundaries(LABs)to high-angle boundaries(HABs).Ni16Si7Ti6 particles further inhibit the growth of recrystallized grains through the pinning effect.Based on the dynamic recrystallization behavior,a processing map of the alloy is built up to obtain the optimal processing parameters.Guided by the processing map,a hot-extruded Cu-15 Ni-8Sn alloy with a fine-grained microstructure is obtained,which shows excellent elongation of 30%and ultimate tensile strength of 910 MPa.展开更多
Wear behaviors of a peak-aged Cu-15Ni-8Sn alloy fabricated by powder metallurgy were investigated.The results indicated that the friction coefficients and the wear rates of Cu-15Ni-8Sn alloy within a normal load range...Wear behaviors of a peak-aged Cu-15Ni-8Sn alloy fabricated by powder metallurgy were investigated.The results indicated that the friction coefficients and the wear rates of Cu-15Ni-8Sn alloy within a normal load range of 50−700 N and a sliding speed range of 0.05−2.58 m/s were less than 0.14 and 2.8×10−6 mm3/mm,respectively.Stribeck-like curve and wear map were developed to describe the oil-lubrication mechanism and wear behavior.The equation of the dividing line between zones of safe and unsafe wear life was determined.Lubricating oil was squeezed into micro-cracks under severe wear conditions.In addition,the lubricating oil reacted with Cu-15Ni-8Sn alloy to generate the corresponding sulfides,which hindered the repair of micro-cracks,promoted cracks growth,and led to delamination.This work has established guidelines for the application of the Cu-15Ni-8Sn alloy under oil-lubricated conditions through developing wear map.展开更多
The ageing behavior of the mechanically alloyed Cu-15Ni-8Sn alloy has been studied. Compared with the alloys prepared by casting and rapid solidification, the modulation structure developed during ageing process of th...The ageing behavior of the mechanically alloyed Cu-15Ni-8Sn alloy has been studied. Compared with the alloys prepared by casting and rapid solidification, the modulation structure developed during ageing process of those prepared by mechanical alloying is finer and much more uniform, which leads to a higher peak hardness. However, their spinodal decomposition temperature are almost the same. Cold deformation prior to ageing not only accelerates the ageing process but also increases the peak hardness of the alloy.展开更多
Tribological behavior of Cu-15Ni-8Sn(mass fraction, %) alloy against GCr15 ring under various loads was investigated on a ring-on-block tester in oil lubrication. The results showed that the wear rate increased slowly...Tribological behavior of Cu-15Ni-8Sn(mass fraction, %) alloy against GCr15 ring under various loads was investigated on a ring-on-block tester in oil lubrication. The results showed that the wear rate increased slowly from 1.7×10^(-7) to 9.8× 10^(-7) mm^3/mm under the load lower than 300 N, and then increased dramatically to the climax of 216×10^(-7) mm^3/mm under the load over 300 N, which indicated the transition of wear mechanism with the increase of applied load. The wear mechanism mainly was plastic deformation and abrasive wear under the load less than 300 N. As the applied load was more than 300 N, the wear mechanism of Cu-15Ni-8Sn alloy primarily was delamination wear. Besides, the transition can also be confirmed from the different morphologies of worn surface, subsurface and wear debris. It is distinctly indicated that the appearance of flaky debris at the applied load over 300 N may be a critical point for the change of wear mechanism.展开更多
The microstructures of spinodal phases in Cu-15Ni-8Sn alloy were studied by TEM. It was found that when the alloy is completely in a as-quenched state, spinodal decomposition is quick. Ordering appears after spinodal ...The microstructures of spinodal phases in Cu-15Ni-8Sn alloy were studied by TEM. It was found that when the alloy is completely in a as-quenched state, spinodal decomposition is quick. Ordering appears after spinodal decomposition. The ordered phase with DO22 structure has three variants obtained from coarsening spinodal structure. The reason of ordering appeared after spinodal decomposition is that the content of solute atoms needed by ordering is higher than the average, which can be reached by the composition fluctuation of spinodal decomposition. It was speculated that the morphology of the ordered phase is needle-like.展开更多
Corrosion resistance of laser powder bed fusion(LPBF)Cu-15Ni-8Sn alloys is crucial towards its practical application in marine engineering.In this work,corrosion behavior of LPBF Cu-15Ni-8Sn alloy was com-prehensively...Corrosion resistance of laser powder bed fusion(LPBF)Cu-15Ni-8Sn alloys is crucial towards its practical application in marine engineering.In this work,corrosion behavior of LPBF Cu-15Ni-8Sn alloy was com-prehensively investigated.The results suggest that LPBF Cu-15Ni-8Sn alloy exhibits superior corrosion re-sistance than the conventional casting counterpart and their corrosion behavior is highly associated with Sn segregation.Generally,a triple-layer film will be formed on the surface of LPBF Cu-15Ni-8Sn alloy when being exposed to 3.5 wt%NaCl solution.To be more detailed,the abundance of nanoscale Sn-rich precipitates at the molten pool boundaries promotes the initial formation of a thick inner layer,where Ni and Sn tend to be distributed at inner and outer positions of the layer,respectively.In contrast,the inner layer on molten pools is much thinner ascribed to a lower Sn content,facilitating the earlier nucleation and growth of a compact middle layer that is mainly composed of numerous Cu-rich nanoparticles.At the outmost position,CuO,Cu(OH)_(2) and Ni(OH)_(2) constitute the major composition of the loose layer.The results of this study could contribute to the optimal design and processing of additively manufactured Cu-Ni-Sn alloys.展开更多
The microstructures and mechanical properties of the directionally solidified Cu-15Ni-8Sn alloy were investigated at solidification rates ranging from 100 to 3000μm/s.The results showed that the solidification rate s...The microstructures and mechanical properties of the directionally solidified Cu-15Ni-8Sn alloy were investigated at solidification rates ranging from 100 to 3000μm/s.The results showed that the solidification rate significantly affects the phase distribution of the as-cast Cu-15Ni-8Sn alloy.The primary and secondary dendritic spacing reduces and eventually becomes stable as the solidification rate increases.Meanwhile,the size of the primary phase decreases,and its distribution becomes more uniform.The most severe segregation problem of this alloy has been greatly improved.Upon solidification at 100μm/s,the as-cast Cu-15Ni-8Sn alloy consists of the α-Cu matrix,γ-CuNi_(2)Sn phase,discontinuous precipitation structure,modulated structure,and DO_(22) ordered phases.However,as the solidification rate increases,the discontinuous precipitation structure,modulated structures,and DO_(22) ordered phases decrease and even disappear,reducing hardness.As the solidification rate increases,after homogenization treatment,the composition and microhardness distributions of Cu-15Ni-8Sn alloy become more uniform.The time for homogenization is also shortened.It reduces production energy usage and facilitates further mechanical processing.展开更多
文摘By means of the measurement of mechnical properties and resistivity and X-ray diffraction and transmission microscopy,the effect of cold deformation on the kinetics of spinodal decomposition of Cu-9Ni-6Sn-0.3Ce alloy was studied.The strengthening process of the cold-worked and aged alloy was found to be accelerated.Using the theory of dislocation,the strengthening in cold-worked alloy can be attributed to the acceleration of spinodal process.
文摘By measurement of mechanical and electrical properties,modulation wavelength,TEM techniques,etc.,the effect of Y on the spinodal decomposition in a Cu-9Ni-6Sn alloy has been studied.The results show that Y can accelerate spinodal decomposition in the alloy,hinder the growth of celluoid structurers occurring at grain boundaries,and improve the combination of strength and plasticity.
基金Project(2015A030312003) supported by the Guangdong Natural Science Foundation for Research Team,China
文摘Effect of Si and Ti on dynamic recrystallization(DRX)of Cu-15Ni-8 Sn alloy was studied using hot compression tests over deformation temperature range of 750-950℃and strain rate range of 0.001-10 s^-1.The results show that the dynamic recrystallization behavior during hot deformation is significantly affected by the trace elements of Si and Ti.The addition of Si and Ti promotes the formation of Ni16Si7Ti6 particles during hot deformation,which promotes the nucleation of dynamic recrystallization by accelerating the transition from low-angle boundaries(LABs)to high-angle boundaries(HABs).Ni16Si7Ti6 particles further inhibit the growth of recrystallized grains through the pinning effect.Based on the dynamic recrystallization behavior,a processing map of the alloy is built up to obtain the optimal processing parameters.Guided by the processing map,a hot-extruded Cu-15 Ni-8Sn alloy with a fine-grained microstructure is obtained,which shows excellent elongation of 30%and ultimate tensile strength of 910 MPa.
基金Projects(2017YFB0306105,2018YFE0306100)supported by the National Key Research and Development Program of China
文摘Wear behaviors of a peak-aged Cu-15Ni-8Sn alloy fabricated by powder metallurgy were investigated.The results indicated that the friction coefficients and the wear rates of Cu-15Ni-8Sn alloy within a normal load range of 50−700 N and a sliding speed range of 0.05−2.58 m/s were less than 0.14 and 2.8×10−6 mm3/mm,respectively.Stribeck-like curve and wear map were developed to describe the oil-lubrication mechanism and wear behavior.The equation of the dividing line between zones of safe and unsafe wear life was determined.Lubricating oil was squeezed into micro-cracks under severe wear conditions.In addition,the lubricating oil reacted with Cu-15Ni-8Sn alloy to generate the corresponding sulfides,which hindered the repair of micro-cracks,promoted cracks growth,and led to delamination.This work has established guidelines for the application of the Cu-15Ni-8Sn alloy under oil-lubricated conditions through developing wear map.
文摘The ageing behavior of the mechanically alloyed Cu-15Ni-8Sn alloy has been studied. Compared with the alloys prepared by casting and rapid solidification, the modulation structure developed during ageing process of those prepared by mechanical alloying is finer and much more uniform, which leads to a higher peak hardness. However, their spinodal decomposition temperature are almost the same. Cold deformation prior to ageing not only accelerates the ageing process but also increases the peak hardness of the alloy.
基金Project(2016YFB0301402)supported by the National Key Research and Development Program of ChinaProject(CSU20151024)supported by the Innovation-driven Plan in Central South University,China
文摘Tribological behavior of Cu-15Ni-8Sn(mass fraction, %) alloy against GCr15 ring under various loads was investigated on a ring-on-block tester in oil lubrication. The results showed that the wear rate increased slowly from 1.7×10^(-7) to 9.8× 10^(-7) mm^3/mm under the load lower than 300 N, and then increased dramatically to the climax of 216×10^(-7) mm^3/mm under the load over 300 N, which indicated the transition of wear mechanism with the increase of applied load. The wear mechanism mainly was plastic deformation and abrasive wear under the load less than 300 N. As the applied load was more than 300 N, the wear mechanism of Cu-15Ni-8Sn alloy primarily was delamination wear. Besides, the transition can also be confirmed from the different morphologies of worn surface, subsurface and wear debris. It is distinctly indicated that the appearance of flaky debris at the applied load over 300 N may be a critical point for the change of wear mechanism.
文摘The microstructures of spinodal phases in Cu-15Ni-8Sn alloy were studied by TEM. It was found that when the alloy is completely in a as-quenched state, spinodal decomposition is quick. Ordering appears after spinodal decomposition. The ordered phase with DO22 structure has three variants obtained from coarsening spinodal structure. The reason of ordering appeared after spinodal decomposition is that the content of solute atoms needed by ordering is higher than the average, which can be reached by the composition fluctuation of spinodal decomposition. It was speculated that the morphology of the ordered phase is needle-like.
基金financially supported by the National Natural Science Foundation of China(No.51901018)Young Elite Scientists Sponsorship Program by China Association for Science and Tech-nology(YESS,No.2019QNRC001)+3 种基金the Fundamental Research Funds for the Central Universities(No.FRF-AT-20-07,06500119)the Nat-ural Science Foundation of Beijing Municipality(No.2212037)the National Science and Technology Resources Investigation Program of China(No.2019FY101400)the National Natural Science Foundation of China(No.52104368).
文摘Corrosion resistance of laser powder bed fusion(LPBF)Cu-15Ni-8Sn alloys is crucial towards its practical application in marine engineering.In this work,corrosion behavior of LPBF Cu-15Ni-8Sn alloy was com-prehensively investigated.The results suggest that LPBF Cu-15Ni-8Sn alloy exhibits superior corrosion re-sistance than the conventional casting counterpart and their corrosion behavior is highly associated with Sn segregation.Generally,a triple-layer film will be formed on the surface of LPBF Cu-15Ni-8Sn alloy when being exposed to 3.5 wt%NaCl solution.To be more detailed,the abundance of nanoscale Sn-rich precipitates at the molten pool boundaries promotes the initial formation of a thick inner layer,where Ni and Sn tend to be distributed at inner and outer positions of the layer,respectively.In contrast,the inner layer on molten pools is much thinner ascribed to a lower Sn content,facilitating the earlier nucleation and growth of a compact middle layer that is mainly composed of numerous Cu-rich nanoparticles.At the outmost position,CuO,Cu(OH)_(2) and Ni(OH)_(2) constitute the major composition of the loose layer.The results of this study could contribute to the optimal design and processing of additively manufactured Cu-Ni-Sn alloys.
基金supported by the National Key Research and Development Program of China(Grant No.2020YFA0714400)Science and Technology Projects of Jiangxi Provincial Department of Education(Grant Nos.GJ210843 and GJJ200873)+2 种基金Scientific Research Starting Foundation for Advanced Talents of Jiangxi University of Science and Technology(Grant No.205200100570)the Project of the Key Scientific and Technological of Jiangxi Province(Grant No.20181BCB19003)Ningbo Enterprise Innovation Consortium Special Project(Grant No.2021H003).
文摘The microstructures and mechanical properties of the directionally solidified Cu-15Ni-8Sn alloy were investigated at solidification rates ranging from 100 to 3000μm/s.The results showed that the solidification rate significantly affects the phase distribution of the as-cast Cu-15Ni-8Sn alloy.The primary and secondary dendritic spacing reduces and eventually becomes stable as the solidification rate increases.Meanwhile,the size of the primary phase decreases,and its distribution becomes more uniform.The most severe segregation problem of this alloy has been greatly improved.Upon solidification at 100μm/s,the as-cast Cu-15Ni-8Sn alloy consists of the α-Cu matrix,γ-CuNi_(2)Sn phase,discontinuous precipitation structure,modulated structure,and DO_(22) ordered phases.However,as the solidification rate increases,the discontinuous precipitation structure,modulated structures,and DO_(22) ordered phases decrease and even disappear,reducing hardness.As the solidification rate increases,after homogenization treatment,the composition and microhardness distributions of Cu-15Ni-8Sn alloy become more uniform.The time for homogenization is also shortened.It reduces production energy usage and facilitates further mechanical processing.
