This article studies the phase transformation of the metastable β-Ti-A1-Mo-V-Cr-Zr alloy （Ti-1300） to disclose the morphological reason for its high strength and high fracture toughness. It has been found that its ...This article studies the phase transformation of the metastable β-Ti-A1-Mo-V-Cr-Zr alloy （Ti-1300） to disclose the morphological reason for its high strength and high fracture toughness. It has been found that its ultrahigh strength （ultimate tensile strength exceeds 1 400 MPa） owes mainly to the spheroidization of the α-phase, while the high fracture toughness （exceeds 81 MPa·m^1/2） to the special lath-shaped α-particles. Compared to the needle-shaped second α-articles, the coarser lath-shaped ones remove the stress concentration at the lath tips and consequently benefit improvement of fracture toughness. The article also describes shape evolution of the α-particles during aging thermodynamically and kinetically, and suggests an optimized aging processing to achieve an ideal balance between high strength and high toughness for this alloy.展开更多
The influence of pre-deformation on phase transformations,microstructures and hardening response in nearβTi alloy Ti5Al-3Mo-3V-2Cr-2Zr-1Nb-1Fe(wt%)during aging treatment was studied.The results show that obviousαpha...The influence of pre-deformation on phase transformations,microstructures and hardening response in nearβTi alloy Ti5Al-3Mo-3V-2Cr-2Zr-1Nb-1Fe(wt%)during aging treatment was studied.The results show that obviousαphase refinement and stronger age hardening effect can be achieved when the alloy is slightly deformed before aging treatment.Because the formation of intermediate phases(O′,ωand O′′)suppresses long-range stress induced martensitic transformation and mechanical twinning,the alloy is mainly deformed via dislocation slipping during loading.Large numbers of crystal defects are generated during predeformation.With increasing the predeformation,the number density of dislocations increases gradually.These crystal defects generated by pre-deformation may partly annihilate upon early aging,but the precipitation ofαcan also be promoted,resulting in refinedαprecipitates.In the sample with 5%pre-strain,the average thickness ofαprecipitates decreases by 57%after aging at 600℃ compared with the sample without pre-strain,and the number density increases from 7.0±1 laths/μm^(2)to 22.0±3 laths/μm^(2).Some platelet-shapedαphases form when the samples experience comparably large pre-strains such as 12%and 20%.It proves that the refinedαprecipitates and better hardening effect can be achieved by pre-deformation plus aging treatment for titanium alloy.展开更多
Glass-forming ability（GFA） and mechanical properties of（Zr_（0.58）Nb_（0.03）Cu_（0.16）Ni_（0.13）Al_（0.10））_（100-x）Lu_x（x= 0-3 at%） alloys have been investigated.The GFA of Zr_（58）Nb_3Cu_（16）Ni_（13）...Glass-forming ability（GFA） and mechanical properties of（Zr_（0.58）Nb_（0.03）Cu_（0.16）Ni_（0.13）Al_（0.10））_（100-x）Lu_x（x= 0-3 at%） alloys have been investigated.The GFA of Zr_（58）Nb_3Cu_（16）Ni_（13）Al_（10） alloy is dramatically enhanced by adding Lu.The（Zr_（0.58）Nb_（0.03）Cu_（0.16）Ni_（0.13）Al_（0.10））_（98）Lu_2 alloy possesses the highest GFA in the studied Zr-Nb-Cu-Ni-Al-Lu alloys,with its critical diameter for glass formation reaching 20 mm by copper-mould casting method,while that of the Lu-free Zr_（58）Nb_3Cu_（16）Ni_（13）Al_（10） alloy is 7 mm.The critical diameters of（Zr_（0.58）Nb_（0.03）Cu_（0.16）Ni_（0.13）Al_（0.10））_（100-x）Lu_x（x =1 at%and 3 at%） alloys are 15 mm and 12 mm,respectively.The Lu addition to Zr_（58）Nb_3Cu_（16）Ni_（13）Al_（10） alloy induces the change of initial crystallization phases from face-centred-cubic Zr_2Ni and tetragonal Zr_2Ni phases for the Lu-free Zr_（58）Nb_3Cu_（16）Ni_（13）Al_（10） alloy to an icosahedral quasi-crystalline phase for the Lu-doped alloys,which may be the origin for the enhanced GFA of the Lu-doped alloys.The compressive fracture strength and plastic strain of the bulk glassy（Zr_（0.58）Nb_（0.03）Cu_（0.16）Ni_（0.13）Al_（0.10））_（98）Lu_2 alloy are1 610 MPa and 1.5%,respectively.展开更多
To determine the liquid-solid phase equilibria of the Nb-Si-Ti ternary system, Nb-Si-Ti alloys of different compositions are prepared. By means of scanning electron microscopy （SEM）, X-ray diffraction （XRD） and el...To determine the liquid-solid phase equilibria of the Nb-Si-Ti ternary system, Nb-Si-Ti alloys of different compositions are prepared. By means of scanning electron microscopy （SEM）, X-ray diffraction （XRD） and electron probe microanalysis （EPMA）, the phases in the alloys, such as Si-based solutions, Ti（Nb）Si, Ti（Nb）Si2, Nb（Ti）Si2, Ti（Nb）5Si4, Nb（Ti）5Si3, Ti（Nb）5Si3, Nb（Ti）3Si and Nb-based solutions are identified, and the phase evolution is analyzed. As a result, the microstmctural and microchemical evidence provides a clear definition of the Nb-Si-Ti liquidus surface projection and indicates that the ternary phase diagram has seven transition reactions.展开更多
基金National Basic Research Program of China (2007CB613805)
文摘This article studies the phase transformation of the metastable β-Ti-A1-Mo-V-Cr-Zr alloy （Ti-1300） to disclose the morphological reason for its high strength and high fracture toughness. It has been found that its ultrahigh strength （ultimate tensile strength exceeds 1 400 MPa） owes mainly to the spheroidization of the α-phase, while the high fracture toughness （exceeds 81 MPa·m^1/2） to the special lath-shaped α-particles. Compared to the needle-shaped second α-articles, the coarser lath-shaped ones remove the stress concentration at the lath tips and consequently benefit improvement of fracture toughness. The article also describes shape evolution of the α-particles during aging thermodynamically and kinetically, and suggests an optimized aging processing to achieve an ideal balance between high strength and high toughness for this alloy.
基金Natural Science Foundation of Shandong Province(ZR2022QE115)Liaocheng City Key Research Plan(2022YDSF85)+4 种基金Liaocheng University Doctoral Initiation Fund(318052132)Liaocheng University Students Innovation Plan(CXCY2023029)National Natrual Science Foundation of China(51671012,51671007,52174346)International Science and Technology Cooperation Program of China(2015DFA51430)Aeronautical Science Foundation of China(2015ZF51069)。
文摘The influence of pre-deformation on phase transformations,microstructures and hardening response in nearβTi alloy Ti5Al-3Mo-3V-2Cr-2Zr-1Nb-1Fe(wt%)during aging treatment was studied.The results show that obviousαphase refinement and stronger age hardening effect can be achieved when the alloy is slightly deformed before aging treatment.Because the formation of intermediate phases(O′,ωand O′′)suppresses long-range stress induced martensitic transformation and mechanical twinning,the alloy is mainly deformed via dislocation slipping during loading.Large numbers of crystal defects are generated during predeformation.With increasing the predeformation,the number density of dislocations increases gradually.These crystal defects generated by pre-deformation may partly annihilate upon early aging,but the precipitation ofαcan also be promoted,resulting in refinedαprecipitates.In the sample with 5%pre-strain,the average thickness ofαprecipitates decreases by 57%after aging at 600℃ compared with the sample without pre-strain,and the number density increases from 7.0±1 laths/μm^(2)to 22.0±3 laths/μm^(2).Some platelet-shapedαphases form when the samples experience comparably large pre-strains such as 12%and 20%.It proves that the refinedαprecipitates and better hardening effect can be achieved by pre-deformation plus aging treatment for titanium alloy.
基金Funded by the National Natural Science Foundation of China(Nos.51101133,51101134)the Encouraging Foundation for Outstanding Youth Scientists of Shandong Province,China(No.BS2012CL036)the Natural Science Foundation of Shandong Province,China(No.ZR2011EL025)
文摘Glass-forming ability（GFA） and mechanical properties of（Zr_（0.58）Nb_（0.03）Cu_（0.16）Ni_（0.13）Al_（0.10））_（100-x）Lu_x（x= 0-3 at%） alloys have been investigated.The GFA of Zr_（58）Nb_3Cu_（16）Ni_（13）Al_（10） alloy is dramatically enhanced by adding Lu.The（Zr_（0.58）Nb_（0.03）Cu_（0.16）Ni_（0.13）Al_（0.10））_（98）Lu_2 alloy possesses the highest GFA in the studied Zr-Nb-Cu-Ni-Al-Lu alloys,with its critical diameter for glass formation reaching 20 mm by copper-mould casting method,while that of the Lu-free Zr_（58）Nb_3Cu_（16）Ni_（13）Al_（10） alloy is 7 mm.The critical diameters of（Zr_（0.58）Nb_（0.03）Cu_（0.16）Ni_（0.13）Al_（0.10））_（100-x）Lu_x（x =1 at%and 3 at%） alloys are 15 mm and 12 mm,respectively.The Lu addition to Zr_（58）Nb_3Cu_（16）Ni_（13）Al_（10） alloy induces the change of initial crystallization phases from face-centred-cubic Zr_2Ni and tetragonal Zr_2Ni phases for the Lu-free Zr_（58）Nb_3Cu_（16）Ni_（13）Al_（10） alloy to an icosahedral quasi-crystalline phase for the Lu-doped alloys,which may be the origin for the enhanced GFA of the Lu-doped alloys.The compressive fracture strength and plastic strain of the bulk glassy（Zr_（0.58）Nb_（0.03）Cu_（0.16）Ni_（0.13）Al_（0.10））_（98）Lu_2 alloy are1 610 MPa and 1.5%,respectively.
基金National Natural Science Foundation of China(51375233)State Key Laboratory of Advanced Brazing Filler Metals & Technology(Zhengzhou Research Institute of Mechanical Engineering)(SKLABFMT201704)Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)
基金National High-tech Research and Development Pro-gram(2006AA03Z102)Aeronautical Science Foundation of China(2006ZF51069)
文摘To determine the liquid-solid phase equilibria of the Nb-Si-Ti ternary system, Nb-Si-Ti alloys of different compositions are prepared. By means of scanning electron microscopy （SEM）, X-ray diffraction （XRD） and electron probe microanalysis （EPMA）, the phases in the alloys, such as Si-based solutions, Ti（Nb）Si, Ti（Nb）Si2, Nb（Ti）Si2, Ti（Nb）5Si4, Nb（Ti）5Si3, Ti（Nb）5Si3, Nb（Ti）3Si and Nb-based solutions are identified, and the phase evolution is analyzed. As a result, the microstmctural and microchemical evidence provides a clear definition of the Nb-Si-Ti liquidus surface projection and indicates that the ternary phase diagram has seven transition reactions.
