A study was conducted to better understand how different parameters, namely, regression aging time and regression aging temperature, affect the creep aging properties, i.e., the creep deformation and performance of Al...A study was conducted to better understand how different parameters, namely, regression aging time and regression aging temperature, affect the creep aging properties, i.e., the creep deformation and performance of Al-Zn-MgCu alloy during regressive reaging. The corresponding creep strain and mechanical properties of samples were studied by conducting creep tests and uniaxial tensile tests. The electrical conductivity was measured using an eddy-current conductivity meter. The microstructures were observed by transmission electron microscopy(TEM). With the increase in regression aging time, the steady creep strain first increased and then decreased, and reached the maximum at 45 min.The steady creep strain increased with the increase in regression aging temperature, and reached the maximum at 200 ℃.The level of steady creep strain was determined by precipitation and dislocation recovery. Creep aging strengthens 7B50-RRA treated with regression aging time at 190 ℃ for 10 min, and the difference in the mechanical properties of alloy becomes smaller. The diffusion of solute atoms reduces the scattering of electrons, leading to a significant improvement in electrical conductivity and stress corrosion cracking(SCC) resistance after creep aging. The findings of this study could help in the application of creep aging forming(CAF) technology in Al-Zn-Mg-Cu alloy under RRA treatment.展开更多
Behaviors,immunities and growth performances of suckling calves to either fed milk through barrel feeding or artificial nipple feeding were investigated in this study.Seventy-two newborn female suckling Holstein calve...Behaviors,immunities and growth performances of suckling calves to either fed milk through barrel feeding or artificial nipple feeding were investigated in this study.Seventy-two newborn female suckling Holstein calves were selected and divided into two treatments which fed regular milk through milk barrels or artificial nipples.The behaviors′parameters were measured on 14,29 and 44 days.Body weight and body size of the calves were recorded on 15,30 and 45 days.Immune indicators were collected in quiet situation on 15,30 and 45 days.Compared with the barrel feeding method,calves fed by artificial nipples had less non-nutritive behaviors,stronger growth performances and higher immune levels.Artificial nipples gave calves sucking conditions and reduced the motivation of calves to suck each other,which might promote the development of complex stomachs,allow food to be better digested and more effective.It also reduced cross-infection indirectly which increased the calves'immunities.展开更多
基金Project(2017YFB0306300) supported by the National key R&D Program of ChinaProjects(51675538, 51905551)supported by the National Natural Science Foundation of ChinaProject(ZZYJKT2019-11) supported by Free Exploration Project of State Key Laboratory of High performance Complex Manufacturing,China。
文摘A study was conducted to better understand how different parameters, namely, regression aging time and regression aging temperature, affect the creep aging properties, i.e., the creep deformation and performance of Al-Zn-MgCu alloy during regressive reaging. The corresponding creep strain and mechanical properties of samples were studied by conducting creep tests and uniaxial tensile tests. The electrical conductivity was measured using an eddy-current conductivity meter. The microstructures were observed by transmission electron microscopy(TEM). With the increase in regression aging time, the steady creep strain first increased and then decreased, and reached the maximum at 45 min.The steady creep strain increased with the increase in regression aging temperature, and reached the maximum at 200 ℃.The level of steady creep strain was determined by precipitation and dislocation recovery. Creep aging strengthens 7B50-RRA treated with regression aging time at 190 ℃ for 10 min, and the difference in the mechanical properties of alloy becomes smaller. The diffusion of solute atoms reduces the scattering of electrons, leading to a significant improvement in electrical conductivity and stress corrosion cracking(SCC) resistance after creep aging. The findings of this study could help in the application of creep aging forming(CAF) technology in Al-Zn-Mg-Cu alloy under RRA treatment.
基金Supported by the National Science and Technology Support Project(2012BAD12B05)。
文摘Behaviors,immunities and growth performances of suckling calves to either fed milk through barrel feeding or artificial nipple feeding were investigated in this study.Seventy-two newborn female suckling Holstein calves were selected and divided into two treatments which fed regular milk through milk barrels or artificial nipples.The behaviors′parameters were measured on 14,29 and 44 days.Body weight and body size of the calves were recorded on 15,30 and 45 days.Immune indicators were collected in quiet situation on 15,30 and 45 days.Compared with the barrel feeding method,calves fed by artificial nipples had less non-nutritive behaviors,stronger growth performances and higher immune levels.Artificial nipples gave calves sucking conditions and reduced the motivation of calves to suck each other,which might promote the development of complex stomachs,allow food to be better digested and more effective.It also reduced cross-infection indirectly which increased the calves'immunities.
