To better understand the hot deformation behaviors of Hastelloy C-276 alloy under elevated temperatures,hot tensile tests were carried out in the temperature range of 1223−1423 K and the strain rate range of 0.01−10 s...To better understand the hot deformation behaviors of Hastelloy C-276 alloy under elevated temperatures,hot tensile tests were carried out in the temperature range of 1223−1423 K and the strain rate range of 0.01−10 s^−1,respectively.Based on the modified Zerilli−Armstrong,modified Johnson-Cook,and strain-compensated Arrheniustype models,three constitutive equations were established to describe the high-temperature flow stress of this alloy.Meanwhile,the predictability of the obtained models was evaluated by the calculation of correlation coefficients(r)and absolute errors(Δ),where the values of r for the modified Zerilli−Armstrong,Johnson−Cook,and Arrhenius-type constitutive models were computed to be 0.935,0.968 and 0.984,and the values ofΔwere calculated to be 13.4%,10.5%and 6.7%,respectively.Moreover,the experimental and predicted flow stresses were compared in the strain range of 0.1−0.5,the results further indicated that the obtained modified Arrhenius-type model possessed better predictability on hot flow behavior of Hastelloy C-276.展开更多
The irradiation damage in nickel-base alloy C-276 irradiated with 115 keV Ar ions from low to very high doses was investigated. Structural characterization was performed using transmission electron microscopy （TEM）,...The irradiation damage in nickel-base alloy C-276 irradiated with 115 keV Ar ions from low to very high doses was investigated. Structural characterization was performed using transmission electron microscopy （TEM）, grazing incident X-ray diffraction （GIXRD） and atomic force microscopy （AFM）. High density of interstitial type dislocation loops could be observed at a dose level of around 2.75 displacements per atom （dpa）. With the irradiation dose increased to 27.5 dpa, the average size of loops increased from 5 nm to 16 nm, while the density of the loops decreased from 1.4 × 1011/cm2 to 4.6 × 1010/cm2. When the irradiation dose reached 82.5 dpa, original grains were transformed into subgrains whose sizes observed from TEM were about 20-60 nm. The fragmentation of grains was confirmed by GIXRD. The mean subgrain size was 40 nm, which was obtained from the full width at half maximum （FWHM） of the X-ray diffraction lines using the Scherrer formula and Williamson formula. AFM micrographs showed that nanometer-sized hillocks formed at the dose of 82.5 dpa, which provided further evidence of grain fragmentation at a high irradiation dose.展开更多
Preparing a highly textured,flawless YBa_（2-）Cu_3O_7（YBCO）layer by ion-beam-as sis ted deposition（IBAD）requires a substrate with a smooth surface.In this paper,smooth tapes of Hastelloy C-276,a common template a...Preparing a highly textured,flawless YBa_（2-）Cu_3O_7（YBCO）layer by ion-beam-as sis ted deposition（IBAD）requires a substrate with a smooth surface.In this paper,smooth tapes of Hastelloy C-276,a common template alloy,were prepared by electrochemical polishing,and the surface roughness the tapes was investigating by atomic force microscopy and scanning electron microscopy.By analyzing these results,it was discussed how the processing parameters affect the surface roughness,and it is found the following optimized processing parameters：current density of 0.104 A·cm^（-2）,temperature of 50℃,plate spacing of 9 cm and time of 150 s.With these optimized parameters,the substrate roughness decreases to less than 5 nm,meeting the requirements of IBAD.展开更多
A systematic investigation was carried out to discuss the corrosion and tribocorrosion behaviors of Hastelloy C276 alloy sliding against Al2O3 pin in artificial seawater, using a pin-on-disk tribometer integrated with...A systematic investigation was carried out to discuss the corrosion and tribocorrosion behaviors of Hastelloy C276 alloy sliding against Al2O3 pin in artificial seawater, using a pin-on-disk tribometer integrated with a potentiostat for electrochemical control. The results show that the great decrease of open circuit potential and three orders of magnitude increase of corrosion current density occur caused by friction. There are clearly synergistic effect between corrosion and wear, resulting in corrosion-induced-wear and wear-induced-corrosion in tribocorrosion process. The contribution of pure mechanical wear to total material loss exceeds 70% in all sliding conditions, so mechanical wear is the dominant factor during tribocorrosion. For considering synergistic effect between corrosion and wear, the contribution of wear-induced-corrosion to total material loss is not very high although corrosion rate is greatly accelerated by friction. The fraction of corrosion-induced-wear to the total material loss is high and in the range of 14.6%-20.5% under all sliding conditions.展开更多
基金Project(ZZYJKT2018-06)supported by the State Key Laboratory of High Performance Complex Manufacturing of Central South University,ChinaProject(2019zzts525)supported by the Fundamental Research Funds for the Central Universities of Central South University of China。
文摘To better understand the hot deformation behaviors of Hastelloy C-276 alloy under elevated temperatures,hot tensile tests were carried out in the temperature range of 1223−1423 K and the strain rate range of 0.01−10 s^−1,respectively.Based on the modified Zerilli−Armstrong,modified Johnson-Cook,and strain-compensated Arrheniustype models,three constitutive equations were established to describe the high-temperature flow stress of this alloy.Meanwhile,the predictability of the obtained models was evaluated by the calculation of correlation coefficients(r)and absolute errors(Δ),where the values of r for the modified Zerilli−Armstrong,Johnson−Cook,and Arrhenius-type constitutive models were computed to be 0.935,0.968 and 0.984,and the values ofΔwere calculated to be 13.4%,10.5%and 6.7%,respectively.Moreover,the experimental and predicted flow stresses were compared in the strain range of 0.1−0.5,the results further indicated that the obtained modified Arrhenius-type model possessed better predictability on hot flow behavior of Hastelloy C-276.
基金supported by the National Basic Research Program of China (No. 2007CB209800)National Natural Science Foundation of China(Nos. 10775108, 11075119)the Fundamental Research Funds for the Central Universities (20102020201000013)
文摘The irradiation damage in nickel-base alloy C-276 irradiated with 115 keV Ar ions from low to very high doses was investigated. Structural characterization was performed using transmission electron microscopy （TEM）, grazing incident X-ray diffraction （GIXRD） and atomic force microscopy （AFM）. High density of interstitial type dislocation loops could be observed at a dose level of around 2.75 displacements per atom （dpa）. With the irradiation dose increased to 27.5 dpa, the average size of loops increased from 5 nm to 16 nm, while the density of the loops decreased from 1.4 × 1011/cm2 to 4.6 × 1010/cm2. When the irradiation dose reached 82.5 dpa, original grains were transformed into subgrains whose sizes observed from TEM were about 20-60 nm. The fragmentation of grains was confirmed by GIXRD. The mean subgrain size was 40 nm, which was obtained from the full width at half maximum （FWHM） of the X-ray diffraction lines using the Scherrer formula and Williamson formula. AFM micrographs showed that nanometer-sized hillocks formed at the dose of 82.5 dpa, which provided further evidence of grain fragmentation at a high irradiation dose.
基金financially supported by the National Science Foundation of China(Nos.51571002,51171002 and 51401003)Beijing Municipal Natural Science Foundations(Nos.2132011 and KZ201310005003)
文摘Preparing a highly textured,flawless YBa_（2-）Cu_3O_7（YBCO）layer by ion-beam-as sis ted deposition（IBAD）requires a substrate with a smooth surface.In this paper,smooth tapes of Hastelloy C-276,a common template alloy,were prepared by electrochemical polishing,and the surface roughness the tapes was investigating by atomic force microscopy and scanning electron microscopy.By analyzing these results,it was discussed how the processing parameters affect the surface roughness,and it is found the following optimized processing parameters：current density of 0.104 A·cm^（-2）,temperature of 50℃,plate spacing of 9 cm and time of 150 s.With these optimized parameters,the substrate roughness decreases to less than 5 nm,meeting the requirements of IBAD.
基金Project(LSL-1310)supported by the Open Project of State Key Laboratory of Solid Lubrication,ChinaProject(51171059)supported by the National Natural Science Foundation of China
文摘A systematic investigation was carried out to discuss the corrosion and tribocorrosion behaviors of Hastelloy C276 alloy sliding against Al2O3 pin in artificial seawater, using a pin-on-disk tribometer integrated with a potentiostat for electrochemical control. The results show that the great decrease of open circuit potential and three orders of magnitude increase of corrosion current density occur caused by friction. There are clearly synergistic effect between corrosion and wear, resulting in corrosion-induced-wear and wear-induced-corrosion in tribocorrosion process. The contribution of pure mechanical wear to total material loss exceeds 70% in all sliding conditions, so mechanical wear is the dominant factor during tribocorrosion. For considering synergistic effect between corrosion and wear, the contribution of wear-induced-corrosion to total material loss is not very high although corrosion rate is greatly accelerated by friction. The fraction of corrosion-induced-wear to the total material loss is high and in the range of 14.6%-20.5% under all sliding conditions.
