The precipitation behaviors of the Cu-Ni-Si alloys during aging were studied by analyzing the variations of electric conductivity.The Avrami-equation of phase transformation kinetics and the Avrami-equation of electri...The precipitation behaviors of the Cu-Ni-Si alloys during aging were studied by analyzing the variations of electric conductivity.The Avrami-equation of phase transformation kinetics and the Avrami-equation of electric conductivity during aging were established for Cu-Ni-Si alloys,on the basis of linear relationship between the electric conductivity and the volume fraction of precipitates,and the calculation results coincide well with the experiment ones.The transformation kinetics curves were established to characterize the aging process.The characteristics of precipitates in the supersaturated solid solution alloy aged at 723 K were established,and the results show that the precipitates areβ-Ni3Si andδ-Ni2Si phases.展开更多
Cold worked and annealed supersaturated Cu-2.65Ni-0.6Si and Cu-2.35Ni-0.6Si-0.6Cr alloys were studied. The microstructural parameters evolution, including crystallite size, root mean square strain and dislocation dens...Cold worked and annealed supersaturated Cu-2.65Ni-0.6Si and Cu-2.35Ni-0.6Si-0.6Cr alloys were studied. The microstructural parameters evolution, including crystallite size, root mean square strain and dislocation density was analyzed using Materials Analysis Using Diffraction software （MAUD）. The parameters for both alloys have typical values of cold deformed and subsequently annealed copper based alloy. A net change of the crystallite size, root mean square strain and dislocation density values of the alloys aged at 450 °C for 2.5-3 h seems corresponding to the recovery and recrystallization processes. Addition of Cr as quaternary element did not lead to any drastic changes of post deformation or ageing microstructural parameters and hence of recovery-recrystallization kinetics.展开更多
The energetic and electronic structures of precipitates on the Cu-rich side of Cu-Ni-Si alloys were investigated by using the first-principle calculations based on plane-wave pseudopotential method.The negative format...The energetic and electronic structures of precipitates on the Cu-rich side of Cu-Ni-Si alloys were investigated by using the first-principle calculations based on plane-wave pseudopotential method.The negative formation heats and the cohesive energies of these precipitates were estimated with electronic structure calculations, and their structural stability was also analyzed.The results show thatδ-Ni2Si,γ-Ni5Si2 andβ-Ni3Si precipitates all have great alloying ability and structural stability,which,after comparing their density of states （DOS）,is found attributed to the pseudogap effect near the Fermi level（Ef）and strong hybridization between the Ni-3d and Si-3p states.Compared with the other two precipitates,theδ-Ni2Si precipitate has the greatest structural stability,which is resulted from its lower DOS at Ef and the main bonding peaks slightly moving to the low energy region.展开更多
The effects of trace boron and cerium addition on microstructures and properties of high-strength and high-conductivity Cu-Ni-Si alloys were studied. The results showed that the recrystallization starting temperature ...The effects of trace boron and cerium addition on microstructures and properties of high-strength and high-conductivity Cu-Ni-Si alloys were studied. The results showed that the recrystallization starting temperature of Cu-Ni-Si alloy was greatly raised by adding trace Ce and B, which resulted in that the recrystallization of alloy did not happen until the aging strengthening peak was reached. Thus, the good strengthening effect contributed by both precipitation and cold working was obtained, and not only the peak strength was obviously increased but also the strength peak and conductivity peak appeared at the same aging temperature. The trace addition of Ce and B makes the alloys achieve an excellent combination of high strength and high conductivity.展开更多
基金Project(2006AA03Z517) supported by the National High-tech Research and Development Program of ChinaProject(08MX15) supported by the Mittal Programs of Central South University, China
文摘The precipitation behaviors of the Cu-Ni-Si alloys during aging were studied by analyzing the variations of electric conductivity.The Avrami-equation of phase transformation kinetics and the Avrami-equation of electric conductivity during aging were established for Cu-Ni-Si alloys,on the basis of linear relationship between the electric conductivity and the volume fraction of precipitates,and the calculation results coincide well with the experiment ones.The transformation kinetics curves were established to characterize the aging process.The characteristics of precipitates in the supersaturated solid solution alloy aged at 723 K were established,and the results show that the precipitates areβ-Ni3Si andδ-Ni2Si phases.
文摘Cold worked and annealed supersaturated Cu-2.65Ni-0.6Si and Cu-2.35Ni-0.6Si-0.6Cr alloys were studied. The microstructural parameters evolution, including crystallite size, root mean square strain and dislocation density was analyzed using Materials Analysis Using Diffraction software （MAUD）. The parameters for both alloys have typical values of cold deformed and subsequently annealed copper based alloy. A net change of the crystallite size, root mean square strain and dislocation density values of the alloys aged at 450 °C for 2.5-3 h seems corresponding to the recovery and recrystallization processes. Addition of Cr as quaternary element did not lead to any drastic changes of post deformation or ageing microstructural parameters and hence of recovery-recrystallization kinetics.
基金the National Natural Science Foundation of China(No.50571035)the National High Technology Research and Development Project(863) of China(No.2006AA032528)
文摘The energetic and electronic structures of precipitates on the Cu-rich side of Cu-Ni-Si alloys were investigated by using the first-principle calculations based on plane-wave pseudopotential method.The negative formation heats and the cohesive energies of these precipitates were estimated with electronic structure calculations, and their structural stability was also analyzed.The results show thatδ-Ni2Si,γ-Ni5Si2 andβ-Ni3Si precipitates all have great alloying ability and structural stability,which,after comparing their density of states （DOS）,is found attributed to the pseudogap effect near the Fermi level（Ef）and strong hybridization between the Ni-3d and Si-3p states.Compared with the other two precipitates,theδ-Ni2Si precipitate has the greatest structural stability,which is resulted from its lower DOS at Ef and the main bonding peaks slightly moving to the low energy region.
基金the International Science and Technology Cooperation Project of the Science and Technology Ministry of China (2006DFB53050)
文摘The effects of trace boron and cerium addition on microstructures and properties of high-strength and high-conductivity Cu-Ni-Si alloys were studied. The results showed that the recrystallization starting temperature of Cu-Ni-Si alloy was greatly raised by adding trace Ce and B, which resulted in that the recrystallization of alloy did not happen until the aging strengthening peak was reached. Thus, the good strengthening effect contributed by both precipitation and cold working was obtained, and not only the peak strength was obviously increased but also the strength peak and conductivity peak appeared at the same aging temperature. The trace addition of Ce and B makes the alloys achieve an excellent combination of high strength and high conductivity.
