Duplex-structured TC21 alloy samples were first solution-treated at a higher temperature in theα+βregion(940°C)with furnace cooling(FC),air cooling(AC),and water cooling(WC),followed by a second-stage solution ...Duplex-structured TC21 alloy samples were first solution-treated at a higher temperature in theα+βregion(940°C)with furnace cooling(FC),air cooling(AC),and water cooling(WC),followed by a second-stage solution treatment at a lower temperature in theα+βregion(900°C),and then finally aged at 590°C.The effects of the morphology and quantity ofαphases on the structure and properties of the TC21 alloy after the different heat treatments were analyzed.The in-situ tensile deformation process and crack propagation behavior were observed using scanning electron microscopy(SEM).The quantity of equiaxedαphases as well as the thickness of lamellarαphases reduced,the tensile strength increased firstly and then decreased,the elongation decreased with the increasing cooling rate after the first-stage solution treatment.The amount and size of lamellarαphases increased after the second-stage solution treatment because of sufficient diffusion of the alloying elements,thereby leading to increased tensile strength.The amount of dispersedαphases increased after the third-stage aging treatment owing to the increase in the nucleation rate,resulting in a noteworthy strengthening effect.After the third-stage aging treatment,the first-stage FC sample exhibited better mechanical properties because it contained more equiaxedαandβtrans phases than the first-stage AC and WC samples.展开更多
To study the effect ofαphase morphology(equiaxedα(αE)/lamellarα(αL))on the in situ tensile behavior of TC21 alloy,the slip band,dislocation,crack initiation,and propagation were analyzed by scanning electron micr...To study the effect ofαphase morphology(equiaxedα(αE)/lamellarα(αL))on the in situ tensile behavior of TC21 alloy,the slip band,dislocation,crack initiation,and propagation were analyzed by scanning electron microscopy(SEM)with in situ tensile stage and transmission electron microscopy(TEM).The results show that the slip bands first concentrate in theαE phases and easily truncate at theα/βphase boundaries,whereas the slip bands move across theαlamellae in theαL phase.Microcracks are easily generated inαE orα/βphase boundaries with large plastic deformation.When the quantity ofαL is more thanαE,the crack tip is more easily deflected atαphases orαclusters with different orientations,making the main crack propagation path more zigzag.When the volume fraction ratio ofαE toαL is~3:4,i.e.,the volume fraction ofαE is close to that ofαL,TC21 alloy exhibits better strength and slower crack propagation rate.展开更多
Gd_(2)O_(3):Tb^(3+) nanocrystal co-doped with Zn^(2+)and Li^(+) was prepared by the combination of polyol and solid-phase methods.The synthesized nanoparticles were characterized by X-ray diffraction(XRD),field emissi...Gd_(2)O_(3):Tb^(3+) nanocrystal co-doped with Zn^(2+)and Li^(+) was prepared by the combination of polyol and solid-phase methods.The synthesized nanoparticles were characterized by X-ray diffraction(XRD),field emission scanning electron microscopy(FESEM),transmission electron microscopy(TEM),photoluminescence(PL)spectra and magnetic resonance imaging(MRI).The results revealed that both Gd_(2)O_(3):Tb^(3+)/Zn^(2+) and Gd_(2)O_(3):Tb^(3+)/Li^(+) had cubic unit structures with a spherical shape,and the fluorescence intensity of the nanoparticles reached a maximum at a doping concentration of0.050 mmol%for Zn^(2+) and 2 mol%for Li^(+),respectively.In addition,the T_(1)/T_(2)(longitudinal/transverse relaxation time)-weighted MRI signals got enhanced due to the increased longitudinal relaxivity(r1)and transverse relaxivity(r2)after the doping by metal ions.Therefore,the materials reported here can be used for fluorescence and MR bimodal imaging,as tracers and for fluorescence detections.展开更多
基金This work was financially supported by the Guizhou Science and Technology Fund Project(Nos.[2018]1027,[2019]2165,and[2014]6013)the Engineering Research Center Project from Guizhou Provincial Education Department,China(No.[2017]016).
文摘Duplex-structured TC21 alloy samples were first solution-treated at a higher temperature in theα+βregion(940°C)with furnace cooling(FC),air cooling(AC),and water cooling(WC),followed by a second-stage solution treatment at a lower temperature in theα+βregion(900°C),and then finally aged at 590°C.The effects of the morphology and quantity ofαphases on the structure and properties of the TC21 alloy after the different heat treatments were analyzed.The in-situ tensile deformation process and crack propagation behavior were observed using scanning electron microscopy(SEM).The quantity of equiaxedαphases as well as the thickness of lamellarαphases reduced,the tensile strength increased firstly and then decreased,the elongation decreased with the increasing cooling rate after the first-stage solution treatment.The amount and size of lamellarαphases increased after the second-stage solution treatment because of sufficient diffusion of the alloying elements,thereby leading to increased tensile strength.The amount of dispersedαphases increased after the third-stage aging treatment owing to the increase in the nucleation rate,resulting in a noteworthy strengthening effect.After the third-stage aging treatment,the first-stage FC sample exhibited better mechanical properties because it contained more equiaxedαandβtrans phases than the first-stage AC and WC samples.
基金financially supported by Guizhou Science and Technology Project(Nos.(2018)1027 and(2019)2165)the Engineering Research Center Project from Guizhou Provincial Education Department(No.(2017)016)。
文摘To study the effect ofαphase morphology(equiaxedα(αE)/lamellarα(αL))on the in situ tensile behavior of TC21 alloy,the slip band,dislocation,crack initiation,and propagation were analyzed by scanning electron microscopy(SEM)with in situ tensile stage and transmission electron microscopy(TEM).The results show that the slip bands first concentrate in theαE phases and easily truncate at theα/βphase boundaries,whereas the slip bands move across theαlamellae in theαL phase.Microcracks are easily generated inαE orα/βphase boundaries with large plastic deformation.When the quantity ofαL is more thanαE,the crack tip is more easily deflected atαphases orαclusters with different orientations,making the main crack propagation path more zigzag.When the volume fraction ratio ofαE toαL is~3:4,i.e.,the volume fraction ofαE is close to that ofαL,TC21 alloy exhibits better strength and slower crack propagation rate.
基金financially supported by Guizhou Provincial Education Department Project(Nos.[2017]016 and[2017]238)Guizhou Science and Technology Project(No.[2019]2165)。
文摘Gd_(2)O_(3):Tb^(3+) nanocrystal co-doped with Zn^(2+)and Li^(+) was prepared by the combination of polyol and solid-phase methods.The synthesized nanoparticles were characterized by X-ray diffraction(XRD),field emission scanning electron microscopy(FESEM),transmission electron microscopy(TEM),photoluminescence(PL)spectra and magnetic resonance imaging(MRI).The results revealed that both Gd_(2)O_(3):Tb^(3+)/Zn^(2+) and Gd_(2)O_(3):Tb^(3+)/Li^(+) had cubic unit structures with a spherical shape,and the fluorescence intensity of the nanoparticles reached a maximum at a doping concentration of0.050 mmol%for Zn^(2+) and 2 mol%for Li^(+),respectively.In addition,the T_(1)/T_(2)(longitudinal/transverse relaxation time)-weighted MRI signals got enhanced due to the increased longitudinal relaxivity(r1)and transverse relaxivity(r2)after the doping by metal ions.Therefore,the materials reported here can be used for fluorescence and MR bimodal imaging,as tracers and for fluorescence detections.
