The γ/γ＇ microstructure of a Re-containing Ni-based single crystal super alloy after a two-step aging was studied using scanning electron microscopy （SEM）,transmission electron microscopy （TEM） and scanning tra...The γ/γ＇ microstructure of a Re-containing Ni-based single crystal super alloy after a two-step aging was studied using scanning electron microscopy （SEM）,transmission electron microscopy （TEM） and scanning transmission electron microscopy （STEM）.The crystals were grown by the floating zone （FZ） method.Both cuboidal and spherical γ＇ precipitates were formed after a two-step aging.The size of the cuboidal γ＇ phases first increased and then decreased with the extension of the second-step aging time.Re,Co and Cr strongly concentrated in the γ phase whereas Ni and Al enriched in the γ＇ phase.Thermodynamic calculation by JMatPro was performed to explain the experimental observations.展开更多
Cu-15Ni-8Sn-0.3Nb alloy rods were prepared by means of powder metallurgy followed by hot extrusion.Element maps obtained by electron probe micro analyzer(EPMA)showed that Nb-rich phases were formed and distributed wit...Cu-15Ni-8Sn-0.3Nb alloy rods were prepared by means of powder metallurgy followed by hot extrusion.Element maps obtained by electron probe micro analyzer(EPMA)showed that Nb-rich phases were formed and distributed within grains and at grain boundaries of the Cu-15Ni-8Sn-0.3Nb alloy.Transmission electron microscope(TEM)results indicated that there was no obvious orientation relationship between these phases and the matrix.Spinodal decomposition and ordering transformation appeared at early stages of aging at400°C and caused significant strengthening.Cu-15Ni-8Sn-0.3Nb alloy exhibited both higher strength(ultimate tensile strength>1030MPa)and higher tensile ductility(elongation>9.1%)than Cu-15Ni-8Sn alloy after aging treatment.The improvement was caused by Nb-rich phases at grain boundaries which led o the refinement of grain size and postponed the growth of discontinuous precipitates during aging.展开更多
With Arena strawberry as experimental materials, heat treatments combined with shoot tip culture were used to explore their detoxification effects. The results indicated that if not heated, splitting shoot tips direct...With Arena strawberry as experimental materials, heat treatments combined with shoot tip culture were used to explore their detoxification effects. The results indicated that if not heated, splitting shoot tips directly could not completely remove viruses. On the other hand, it will be obviously improved after shoot tips are heated. Incubators heat treatment （inconstant temperature） with shoot tip culture, constant temperature water bath incubation process with meristem-tip culture, hot air treatment （constant temperature） with apical meristem culture were three methods tested in searching for virus-free of Arena strawberry in this experiment. And their virus-free rates were 78.9%, 86.0% and 50.0% respectively. Of the three methods, the second, constant temperature water bath process with shoot tip culture, with 78.7% survival, is the best. Thus, it can be inferred that constant temperature water bath treatment combined with shoot tip culture might be the most appropriate method to remove viruses of Arena strawberry.展开更多
Unquestionably,aircraft industry plays an important part in both economy and security of a nation.However,few of articles have dealt with the spatial development of this industry sector.The purpose of this article is ...Unquestionably,aircraft industry plays an important part in both economy and security of a nation.However,few of articles have dealt with the spatial development of this industry sector.The purpose of this article is to analyze the dynamics of agglomeration and diffusion of aircraft industry.In a historical view,with some spatial analysis methods,this research discusses the characteristics and patterns of aircraft industry's spatial organization and evolution,globally,nationally and regionally respectively.We find out there is a ‘Matthew effect' in aircraft industry of the world,and the spatial evolution of the industry is consistent with the nation's industrialization process.Then,it concludes that the main agglomeration forces consist of capital,talents,technology and cluster's advantages,and the main diffusion forces include comparative advantages,cost and risk sharing,emerging markets,development policy for backward regions and military requirements.All the factors can be divided into market forces making the spatial development of aircraft industry normal and non-market forces making that irregular.In particular,lessons from the USA and France are expected to be conducive to the rise of China's aircraft industry in the future.展开更多
A novel method,i.e.multi-cyclic quenching and partitioning(M-Q-P)heat treatment,is used to tailor the content of retained austenite(RA)in commercial steels.For 35CrMnSi steel,5 times of Q-P heat treatment can increase...A novel method,i.e.multi-cyclic quenching and partitioning(M-Q-P)heat treatment,is used to tailor the content of retained austenite(RA)in commercial steels.For 35CrMnSi steel,5 times of Q-P heat treatment can increase the content of RA from 8vol.%to 17 vol.%.As a result,the ultimate elongation of the steel is improved from 17.4%after the typical Q-P heat treatment to 27.1%after 5 times of Q-P treatment.Meanwhile,the improved combination of strength and ductility for steels by typical Q-P heat treatment is retained by the multi-cyclic Q-P heat treatment.It is shown that the content of RA in some specific steels,and furthermore their mechanical properties,can be regulated through the M-Q-P.展开更多
基金Project(08dj1400402) supported by the Major Program for the Fundamental Research of Science and Technology Committee of the Shanghai Municipality,ChinaProject(09ZZ16) supported by Innovation Program of Shanghai Municipal Education Committee,China
文摘The γ/γ＇ microstructure of a Re-containing Ni-based single crystal super alloy after a two-step aging was studied using scanning electron microscopy （SEM）,transmission electron microscopy （TEM） and scanning transmission electron microscopy （STEM）.The crystals were grown by the floating zone （FZ） method.Both cuboidal and spherical γ＇ precipitates were formed after a two-step aging.The size of the cuboidal γ＇ phases first increased and then decreased with the extension of the second-step aging time.Re,Co and Cr strongly concentrated in the γ phase whereas Ni and Al enriched in the γ＇ phase.Thermodynamic calculation by JMatPro was performed to explain the experimental observations.
基金Project (2016YFB0301400) supported by the National Key Research and Development Program of ChinaProject (9140A12040515QT48167) supported by the Pre-research Fund of the General Armaments Department of ChinaProject (CSU20151024) supported by the Innovation-driven Plan of Central South University,China
文摘Cu-15Ni-8Sn-0.3Nb alloy rods were prepared by means of powder metallurgy followed by hot extrusion.Element maps obtained by electron probe micro analyzer(EPMA)showed that Nb-rich phases were formed and distributed within grains and at grain boundaries of the Cu-15Ni-8Sn-0.3Nb alloy.Transmission electron microscope(TEM)results indicated that there was no obvious orientation relationship between these phases and the matrix.Spinodal decomposition and ordering transformation appeared at early stages of aging at400°C and caused significant strengthening.Cu-15Ni-8Sn-0.3Nb alloy exhibited both higher strength(ultimate tensile strength>1030MPa)and higher tensile ductility(elongation>9.1%)than Cu-15Ni-8Sn alloy after aging treatment.The improvement was caused by Nb-rich phases at grain boundaries which led o the refinement of grain size and postponed the growth of discontinuous precipitates during aging.
文摘With Arena strawberry as experimental materials, heat treatments combined with shoot tip culture were used to explore their detoxification effects. The results indicated that if not heated, splitting shoot tips directly could not completely remove viruses. On the other hand, it will be obviously improved after shoot tips are heated. Incubators heat treatment （inconstant temperature） with shoot tip culture, constant temperature water bath incubation process with meristem-tip culture, hot air treatment （constant temperature） with apical meristem culture were three methods tested in searching for virus-free of Arena strawberry in this experiment. And their virus-free rates were 78.9%, 86.0% and 50.0% respectively. Of the three methods, the second, constant temperature water bath process with shoot tip culture, with 78.7% survival, is the best. Thus, it can be inferred that constant temperature water bath treatment combined with shoot tip culture might be the most appropriate method to remove viruses of Arena strawberry.
基金The National Natural Science Foundation of China (Grant no.40635026)
文摘Unquestionably,aircraft industry plays an important part in both economy and security of a nation.However,few of articles have dealt with the spatial development of this industry sector.The purpose of this article is to analyze the dynamics of agglomeration and diffusion of aircraft industry.In a historical view,with some spatial analysis methods,this research discusses the characteristics and patterns of aircraft industry's spatial organization and evolution,globally,nationally and regionally respectively.We find out there is a ‘Matthew effect' in aircraft industry of the world,and the spatial evolution of the industry is consistent with the nation's industrialization process.Then,it concludes that the main agglomeration forces consist of capital,talents,technology and cluster's advantages,and the main diffusion forces include comparative advantages,cost and risk sharing,emerging markets,development policy for backward regions and military requirements.All the factors can be divided into market forces making the spatial development of aircraft industry normal and non-market forces making that irregular.In particular,lessons from the USA and France are expected to be conducive to the rise of China's aircraft industry in the future.
文摘A novel method,i.e.multi-cyclic quenching and partitioning(M-Q-P)heat treatment,is used to tailor the content of retained austenite(RA)in commercial steels.For 35CrMnSi steel,5 times of Q-P heat treatment can increase the content of RA from 8vol.%to 17 vol.%.As a result,the ultimate elongation of the steel is improved from 17.4%after the typical Q-P heat treatment to 27.1%after 5 times of Q-P treatment.Meanwhile,the improved combination of strength and ductility for steels by typical Q-P heat treatment is retained by the multi-cyclic Q-P heat treatment.It is shown that the content of RA in some specific steels,and furthermore their mechanical properties,can be regulated through the M-Q-P.
