The microstructures of Ti-14Al-21Nb and Ti-14Al-20Nb-2Mo-3.2V(wt%) alloys have been investikated by transmission electron microscopy(TEM).The phase constitution and the orientation relationship between α2and βwere i...The microstructures of Ti-14Al-21Nb and Ti-14Al-20Nb-2Mo-3.2V(wt%) alloys have been investikated by transmission electron microscopy(TEM).The phase constitution and the orientation relationship between α2and βwere identified by means of the selected area diffraction and the micro-diffraction techniques.Results show that,compared to Ti-14Al-21Nb,the alloying elements Mo and V can greatly increase the fraction of β phase and improve significantly the microstructures of Ti-14Al-20Nb-2Mo-3.2V.The ordered B2 structure is also evident in the residual βgrains of the latter alloy.展开更多
The superplasticity of Ti_3Al intermetallic compounds has been investigated in this paper.The Ti-14Al-21Nb ternary alloy showed 477% elongation at the strain rate of 1.49×10^(-5) s^(-1) and 950℃.The elongation o...The superplasticity of Ti_3Al intermetallic compounds has been investigated in this paper.The Ti-14Al-21Nb ternary alloy showed 477% elongation at the strain rate of 1.49×10^(-5) s^(-1) and 950℃.The elongation of Ti-14Al-21 Nb-3Mo-1V quinary alloy approached to 573% at the strain rate of 4.52×10^(-5) s^(-1) and the same temperature,and it was found that the elongation value in- creased to 1096.4%as temperature was raised up to 980℃ at the same strain rate.Ti_3Al base al- loys were bonded by diffusion bonding technology and good joints were created,the simulated specimens were performed by SPF/DB process.展开更多
The phase transformation and deformation mechanism of the alloy based on composition Ti_3Al with addition of Nb,V,Mo have been studied by use of transmission electron microscopy (TEM).It has been shown that the orient...The phase transformation and deformation mechanism of the alloy based on composition Ti_3Al with addition of Nb,V,Mo have been studied by use of transmission electron microscopy (TEM).It has been shown that the orientation relationship of α_2 phase transformed from β phase is:(0001)α_2// (l10)β,[1210]α_2//[111]β.The present dislocation slip systems in α_2 phase are (1100)[0001] and (1100)<1120>.There also exist α_2 twins which have new twin relationship and the twin plane is (2021).展开更多
In the present paper, the relations between the microstructure and the properties of Ti-14Al-21Nb and Ti-14Al-20Nb-3.5V-2Mo alloys at different temperatures and different cooling rates of heat treatment were re-vealed...In the present paper, the relations between the microstructure and the properties of Ti-14Al-21Nb and Ti-14Al-20Nb-3.5V-2Mo alloys at different temperatures and different cooling rates of heat treatment were re-vealed by X-ray , optical microscope , HVTEM , auto-graphical-analyser and mechanical properties test at roomand high temperature. The experimental results show as follows: at 1040～1120℃ 14h WQ, the microstruc-ture of Ti-14Al-21Nb bar is primary phaseα_2+B2. With temperature increasing, the primary α_2 phase de-crease and the mechanical properties ultimate tensile strength (UTS), yield strength (YS) and elongation(EL) at room temperature increase. When it has reduced the α_2 phase by 50% (at 1080℃/4h WQ) , the me-chanical properties at room temperature are excellent , EL being 10. 5%. Following the α_2 phase reduces contin-uously , UTS, YS are going up, but EL is going down. After heated at two phases range and cooled down tothe room temperature with furnace, the microstructure of Ti-14Al-20Nb-3.5V-2Mo alloy is the equiaxed α_2+needle-like α_2+βphase. The mechanical properties at room temperature and 700℃ are fairly good.展开更多
Microstructures and mechanical properties of Nb-32Ti-7Al alloys containing different V and Zr contents were investigated. The microstructures were characterized using optical microscopy and scanning electron microscop...Microstructures and mechanical properties of Nb-32Ti-7Al alloys containing different V and Zr contents were investigated. The microstructures were characterized using optical microscopy and scanning electron microscopy (SEM). The alloy with V and Zr presents single phase Nb solid solution (Nbss). Tensile testing was carried out at room temperature and 1373 K. The results show that these alloys have good ductility at room temperature. The strengths at room and high temperature increase with the addition of V and Zr, but the room temperature ductility decrease.展开更多
文摘The microstructures of Ti-14Al-21Nb and Ti-14Al-20Nb-2Mo-3.2V(wt%) alloys have been investikated by transmission electron microscopy(TEM).The phase constitution and the orientation relationship between α2and βwere identified by means of the selected area diffraction and the micro-diffraction techniques.Results show that,compared to Ti-14Al-21Nb,the alloying elements Mo and V can greatly increase the fraction of β phase and improve significantly the microstructures of Ti-14Al-20Nb-2Mo-3.2V.The ordered B2 structure is also evident in the residual βgrains of the latter alloy.
文摘The superplasticity of Ti_3Al intermetallic compounds has been investigated in this paper.The Ti-14Al-21Nb ternary alloy showed 477% elongation at the strain rate of 1.49×10^(-5) s^(-1) and 950℃.The elongation of Ti-14Al-21 Nb-3Mo-1V quinary alloy approached to 573% at the strain rate of 4.52×10^(-5) s^(-1) and the same temperature,and it was found that the elongation value in- creased to 1096.4%as temperature was raised up to 980℃ at the same strain rate.Ti_3Al base al- loys were bonded by diffusion bonding technology and good joints were created,the simulated specimens were performed by SPF/DB process.
文摘The phase transformation and deformation mechanism of the alloy based on composition Ti_3Al with addition of Nb,V,Mo have been studied by use of transmission electron microscopy (TEM).It has been shown that the orientation relationship of α_2 phase transformed from β phase is:(0001)α_2// (l10)β,[1210]α_2//[111]β.The present dislocation slip systems in α_2 phase are (1100)[0001] and (1100)<1120>.There also exist α_2 twins which have new twin relationship and the twin plane is (2021).
文摘In the present paper, the relations between the microstructure and the properties of Ti-14Al-21Nb and Ti-14Al-20Nb-3.5V-2Mo alloys at different temperatures and different cooling rates of heat treatment were re-vealed by X-ray , optical microscope , HVTEM , auto-graphical-analyser and mechanical properties test at roomand high temperature. The experimental results show as follows: at 1040～1120℃ 14h WQ, the microstruc-ture of Ti-14Al-21Nb bar is primary phaseα_2+B2. With temperature increasing, the primary α_2 phase de-crease and the mechanical properties ultimate tensile strength (UTS), yield strength (YS) and elongation(EL) at room temperature increase. When it has reduced the α_2 phase by 50% (at 1080℃/4h WQ) , the me-chanical properties at room temperature are excellent , EL being 10. 5%. Following the α_2 phase reduces contin-uously , UTS, YS are going up, but EL is going down. After heated at two phases range and cooled down tothe room temperature with furnace, the microstructure of Ti-14Al-20Nb-3.5V-2Mo alloy is the equiaxed α_2+needle-like α_2+βphase. The mechanical properties at room temperature and 700℃ are fairly good.
文摘Microstructures and mechanical properties of Nb-32Ti-7Al alloys containing different V and Zr contents were investigated. The microstructures were characterized using optical microscopy and scanning electron microscopy (SEM). The alloy with V and Zr presents single phase Nb solid solution (Nbss). Tensile testing was carried out at room temperature and 1373 K. The results show that these alloys have good ductility at room temperature. The strengths at room and high temperature increase with the addition of V and Zr, but the room temperature ductility decrease.
