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A new rhombohedral phase and its 48 variants inβtitanium alloy
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作者 Xin-nan WANG Ming HAN +2 位作者 Fu-rong ZHANG Guang-ming ZHAO Zhi-shou ZHU 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2024年第9期2849-2863,共15页
A new rhombohedral phase(termed R′)in a solution-aging-treated titanium alloy(Ti-4.5Al-6.5Mo-2Cr-2Nb-1V-1Sn-1Zr,wt.%)was identified.Its accurate Bravais lattice parameters were determined by a novel unit cell reconst... A new rhombohedral phase(termed R′)in a solution-aging-treated titanium alloy(Ti-4.5Al-6.5Mo-2Cr-2Nb-1V-1Sn-1Zr,wt.%)was identified.Its accurate Bravais lattice parameters were determined by a novel unit cell reconstruction method based on conventional selected-area electron diffraction(SAED)technique.The orientation relationship between R'phase and BCC phase was revealed.The results show that the R′phase is found to have 48crystallographically equivalent variants,resulting in rather complicated SAED patterns with high-order reflections.A series of in-situ SAED patterns were taken along both low-and high-index zone axes,and all weak and strong reflections arising from the 48 variants were properly explained and directly assigned with self-consistent Miller indices,confirming the presence of the rhombohedral phase.Additionally,some criteria were also proposed for evaluating the indexed results,which together with the Bravais lattice reconstruction method shed light on the microstructure characterization of even unknown phases in other alloys. 展开更多
关键词 titanium alloy rhombohedral phase Bravais lattice reconstruction VARIANT orientation relationship
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Influence of Ni_4Ti_3 precipitates on phase transformation of NiTi shape memory alloy 被引量:4
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作者 江树勇 张艳秋 +3 位作者 赵亚楠 刘思维 胡励 赵成志 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2015年第12期4063-4071,共9页
Ni Ti shape memory alloy samples were aged for 2 h at 573, 723 and 873 K, respectively. Two R-phase variants are observed in the Ni Ti samples aged at 573 and 723 K, where the orientation relationship between the two ... Ni Ti shape memory alloy samples were aged for 2 h at 573, 723 and 873 K, respectively. Two R-phase variants are observed in the Ni Ti samples aged at 573 and 723 K, where the orientation relationship between the two R-phase variants and the B2 matrix is determined. In the Ni Ti samples aged at 573 and 723 K, fine and homogeneous Ni4Ti3 precipitates are coherent with the B2 austenite matrix. The Ni4Ti3 particles precipitate in the grain interior and at the grain boundaries, where the heterogeneous Ni4Ti3 precipitates are coherent, semi-coherent and incoherent with the B2 matrix in the Ni Ti sample aged at 873 K. As for the Ni Ti sample aged at 873 K, one-stage phase transformation from B19' martensite to B2 austenite occurs on heating, but two-stage phase transformation of B2-R-B19' arises on cooling. The Ni Ti sample aged at 723 K shows two-stage phase transformation of B2-R-B19' on cooling as well, but exhibits two-stage phase transformation of B19'-R-B2 on heating. The Ni Ti sample aged at 573 K exhibits three-stage transformation on cooling due to local stress inhomogeneity and local composition inhomogeneity around the Ni4Ti3 precipitates. 展开更多
关键词 shape memory alloy NiTi alloy martensitic transformation heat treatment MICROSTRUCTURE
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In situ study of phase transformations in Ti-6Al-4V-x H alloys 被引量:1
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作者 宗影影 黄树晖 +1 位作者 郭斌 单德彬 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2015年第9期2901-2911,共11页
The hydrogen-induced microstructure evolution and phase transformations in Ti-6Al-4V alloy during heating and cooling were studied.The specimens were heated to 1273 K and subsequently cooled to room temperature.The hy... The hydrogen-induced microstructure evolution and phase transformations in Ti-6Al-4V alloy during heating and cooling were studied.The specimens were heated to 1273 K and subsequently cooled to room temperature.The hydrogen content is up to 0.8%(mass fraction).The hydrogen-induced dynamic phase transformations and the corresponding mechanisms were analyzed.When the hydrogen content increases,the β transus temperature significantly decreases and the magnitude decreases,and the volume fraction of β phase increases.During heating,the phase transformations in hydrogenated Ti-6Al-4V alloys can be divided into three stages,and the phase transformation order is δ→α+H2↑?δ+α′→βH?α′→αH+βH?αH→α+H2↑?α→β?βH→β+H2↑.In addition,the relationship among hydrogenation and Ms and Mf of α′ martensite were determined. 展开更多
关键词 titanium alloy phase transformation HYDROGEN in situ
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Antiphase boundary-like structure in α′′ martensite of TC21 titanium alloy 被引量:2
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作者 许艳飞 刘会群 +2 位作者 易丹青 朱知寿 郑峰 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2012年第6期1366-1371,共6页
The morphology and formation mechanism of the substructure of martensite in TC21 alloy was investigated by XRD and TEM. The results showed that the martensitic transformation from β to α" occurs upon quenching afte... The morphology and formation mechanism of the substructure of martensite in TC21 alloy was investigated by XRD and TEM. The results showed that the martensitic transformation from β to α" occurs upon quenching after solution treatment between 960-1000 ℃. The antiphase boundary (APB)-like structure was observed clearly in the α" martensite plates. The APB-like contrasts exist along the (001) and (020) planes of α" martensite. This APB-like structure of α" martensite was identified as a kind of stacking fault with an APB-like morphology induced by martensitic transformation and not by order/disorder transition. During martensitic transformation, martensitic domains nucleate and grow, eventually encounter each other, resulting in the formation of the APBdike contrast. 展开更多
关键词 titanium alloy martensitic transformation antiphase boundary (APB) crystal structure
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Influence of cooling rate on phase transformation and microstructure of Ti-50.9%Ni shape memory alloy 被引量:4
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作者 张艳秋 江树勇 +1 位作者 赵亚楠 唐明 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2012年第11期2685-2690,共6页
Heat treatment of Ti-50.9%Ni (mole fraction) alloy was studied by differential scanning calorimetry, X-ray diffraction, scanning electron microscopey and energy dispersive X-ray analysis to investigate the influence... Heat treatment of Ti-50.9%Ni (mole fraction) alloy was studied by differential scanning calorimetry, X-ray diffraction, scanning electron microscopey and energy dispersive X-ray analysis to investigate the influence of cooling rate on transformation behavior and microstructures of NiTi shape memory alloy. The experimental results show that three-stage phase transformation can be induced at a very low cooling rate such as cooling in furnace. The cooling rate also has a great influence on the phase transformation temperatures. Both martensitic start transformation temperature (Ms) and martensitic finish transformation temperature (Mf) decrease with the decrease of the cooling rate, and decreasing the cooling rate contributes to enhancing the M→A austenite transformation temperature. The phase transformation hysteresis (Af-Mf) increases with the decrease of the cooling rate. Heat treatment is unable to eliminate the textures formed in hot working of NiTi sample, but can weaken the intensity of them. The cooling rate has little influence on the grain size. 展开更多
关键词 NiTi alloy shape memory alloy phase transformation cooling rate martensitic transformation temperature austenite transformation temperature
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Effect of Ta addition on mechanical properties of 7715D titanium alloy
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作者 王立强 吕维洁 +2 位作者 吕健 覃继宁 张荻 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2012年第3期516-520,共5页
The 7715D titanium alloy added with 2.1% Ta element,nominated as 2Ta,was successfully synthesized using common casting and hot-forging technology.Two kinds of heat treatments were adopted.The phase analysis was identi... The 7715D titanium alloy added with 2.1% Ta element,nominated as 2Ta,was successfully synthesized using common casting and hot-forging technology.Two kinds of heat treatments were adopted.The phase analysis was identified by XRD.The microstructures were observed by optical microscopy(OM) and scanning electron microscopy(SEM).Both room-temperature and high-temperature tensile properties were tested.The results show that the addition of Ta element plays an important role in the mechanical properties of 7715D titanium alloy,which strengths the alloy seriously. 展开更多
关键词 titanium alloy mechanical property phase transformation
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《宁夏工程技术》总目次
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《宁夏工程技术》 CAS 2014年第4期385-388,共4页
关键词 工程技术 钛合金相变 TOURISM RESERVOIR SHRIMP 投资组合模型 地质灾害调查
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1990年总目录
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《航天制造技术》 1990年第6期62-64,共3页
关键词 刘今起 陀螺球 电解加工 张泉林 动平衡法 精密机械加工 电缆接插件 钛合金相变 型号研制 人造金刚石
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Strain-induced α-to-β phase transformation during hot compression in Ti-5Al-5Mo-5V-1Cr-1Fe alloy 被引量:10
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作者 Kai LI Ping YANG 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2019年第2期296-304,共9页
The dynamic phase transformation of Ti-5Al-5Mo-5V-1Cr-1Fe alloy during hot compression below theβtransus temperature was investigated.Strain-inducedα-to-βtransformation is observed in the samples compressed at 0-10... The dynamic phase transformation of Ti-5Al-5Mo-5V-1Cr-1Fe alloy during hot compression below theβtransus temperature was investigated.Strain-inducedα-to-βtransformation is observed in the samples compressed at 0-100 K below theβtransus temperature.The deformation stored energy by compression provides a significant driving force for theα-to-βphase transformation.The re-distribution of the solute elements induced by defects during deformation promotes the occurrence of dynamic transformation.Orientation dependence for theα-to-βphase transformation promotion is observed between{100}-orientated grains and{111}-orientated grains.Incomplete recovery in{111}-orientated grains would create a large amount of diffusion channels,which is in favor of theα-to-βtransformation.The effects of reduction ratio and strain rate on the dynamic phase transformation were also investigated. 展开更多
关键词 titanium alloy hot compression phase transformation orientation dependence
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Effect of Sn on synthesis of nanocrystalline Ti-based alloy with fcc structure 被引量:3
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作者 C.AGUILAR E.PIO +5 位作者 A.MEDINA C.PARRA R.MANGALARAJA P.MARTIN I.ALFONSO K.TELLO 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2020年第8期2119-2131,共13页
The effect of the amount of Sn on the formation of fcc phase in Ti-13 Ta-x Sn(x=3,6,9 and 12,at.%)alloys was studied.The alloys were synthesized by mechanical alloying using a planetary mill,jar and balls of stabilize... The effect of the amount of Sn on the formation of fcc phase in Ti-13 Ta-x Sn(x=3,6,9 and 12,at.%)alloys was studied.The alloys were synthesized by mechanical alloying using a planetary mill,jar and balls of stabilized yttrium.Using Rietveld refinement,it was found that the obtained fcc phase has crystallite size smaller than 10 nm and microstrain larger than 10-3.Both conditions are required to form an fcc phase in Ti-based alloys.For all samples,the microstructure of the fcc phase consists of equiaxial crystallites with sizes smaller than 10 nm.The largest presence of fcc phase in the studied Ti alloy was found with 6 at.%Sn,because this alloy exhibits the largest microstrain(1.5×10-2)and crystallite size of 6.5 nm.Experimental data reveal that a solid solution and an amorphous phase were formed during milling.The necessary conditions to promote the formation of solid solution and amorphous phases were determined using thermodynamic calculations.When the amount of Sn increases,the energy required to form an amorphous phase varies from approximately 10 to approximately-5 k J/mol for 3 and 12 at.%Sn,respectively.The thermodynamic calculations are in agreement with XRD patterns analysis and HRTEM results. 展开更多
关键词 Ti-based alloy phase transformation fcc phase Rietveld analysis mechanical alloying
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α″phase-assisted nucleation to obtain ultrafineαprecipitates for designing high-strength near-βtitanium alloys 被引量:5
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作者 Zhen-yu WANG Li-bin LIU +3 位作者 Di WU Li-gang ZHANG Wan-lin WANG Ke-chao ZHOU 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2020年第10期2681-2696,共16页
The diffusion-multiple method was used to determine the composition of Ti−6Al−4V−xMo−yZr alloy(0.45<x<12,0.5<y<14,wt.%),which can obtain an ultrafine α phase.Results show that Ti−6Al−4V−5Mo−7Zr alloy can ... The diffusion-multiple method was used to determine the composition of Ti−6Al−4V−xMo−yZr alloy(0.45<x<12,0.5<y<14,wt.%),which can obtain an ultrafine α phase.Results show that Ti−6Al−4V−5Mo−7Zr alloy can obtain an ultrafineαphase by using the α″phase assisted nucleation.The bimodal microstructure obtained with the heat-treatment process can confer the alloy with a good balance between the strength and plasticity.The deformation mechanism is the dislocation slip and the{1101}twinning in the primary α phase.The strengthening mechanism is α/β interface strengthening.The interface of(0001)α/(110)β has a platform−step structure,whereas(1120)α/(111)βinterface is flat with no steps. 展开更多
关键词 alloy design high-strength titanium alloy α″phase α/βinterface twin deformation
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Morphology transformation of primary strip α phase in hot working of two-phase titanium alloy 被引量:4
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作者 Xiao-guang FAN He YANG +3 位作者 Peng-fei GAO Rui ZUO Peng-hui LEI Zhe JI 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2017年第6期1294-1305,共12页
Microstructural development in hot working of TA15titanium alloy with primary stripαstructure was investigated withthe aim to globularizeαstrips.Results show that the mechanisms of morphology transformation are the ... Microstructural development in hot working of TA15titanium alloy with primary stripαstructure was investigated withthe aim to globularizeαstrips.Results show that the mechanisms of morphology transformation are the same to the spheroidizationmechanisms of lamellar structure.Boundary splitting and termination migration are more important than coarsening due to the largesize of stripα.Theαstrips are stable in annealing due to the unfavorable geometrical orientation of intra-αboundaries,the largethickness of strip and the geometrical stability ofαparticles.Predeformation and low speed deformation accelerate globularization ofαstrips in the following ways:direct changing of particle shape,promotion of boundary splitting and termination migration byincreasing high angle grain boundaries and interfacial area,promotion of coarsening by forming dislocation structures.Largepredeformation combined with high temperature annealing is a feasible way to globularize stripα. 展开更多
关键词 titanium alloy primary α strips globularization morphology transformation hot working COARSENING
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Mechanically-induced martensite transformation of NiTiFe shape memory alloy subjected to plane strain compression 被引量:3
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作者 Shu-yong JIANG Jun-bo YU +1 位作者 Yan-qiu ZHANG Xiao-dong XING 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2020年第5期1325-1334,共10页
Based on the channel die compression, NiTiFe shape memory alloy(SMA) was subjected to plane strain compression. Mechanically-induced martensite transformation, nanocrystalline and amorphous phase can be observed in th... Based on the channel die compression, NiTiFe shape memory alloy(SMA) was subjected to plane strain compression. Mechanically-induced martensite transformation, nanocrystalline and amorphous phase can be observed in the case of large plastic strain. Mechanically-induced martensite transformation is obviously different from the conventional stress-induced martensite transformation. The former generally occurs after dislocation slip, whereas the latter arises prior to dislocation slip. The occurrence of B19’ martensite phase contributes to accommodating subsequent plastic deformation of NiTiFe SMA. Mechanically-induced B19’ martensite is partially stabilized due to the existence of local high stress field and consequently it is unable to be reverted to B2 austenite phase during unloading. 展开更多
关键词 shape memory alloy NiTiFe alloy plastic deformation martensitic transformation MICROSTRUCTURE
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Phase transformation in titanium alloys:A review
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作者 Chang-chang LIU Yang-huan-zi LI +1 位作者 Ji GU Min SONG 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS 2024年第10期3093-3117,共25页
Due to a series of exceptional properties,titanium and titanium alloys have received extensive attention in recent years.Different from other alloy systems,there are two allotropes and a sequence of metastable phases ... Due to a series of exceptional properties,titanium and titanium alloys have received extensive attention in recent years.Different from other alloy systems,there are two allotropes and a sequence of metastable phases in titanium alloys.By summarizing the recent investigations,the phase transformation processes corresponding to the common phases and also some less reported phases are reviewed.For the phase transformation only involvingαandβphases,it can be divided intoβ→αtransformation and a reverse transformation.The former one has been demonstrated from the orientation relationship betweenαandβphases and the regulation ofαmorphology.For the latter transformation,the role of the stress has been discussed.In terms of the metastable phases,the mechanisms of phase formation and their effects on microstructure and mechanical properties have been discussed.Finally,some suggestions about the development of titanium alloys have been proposed. 展开更多
关键词 titanium alloys phase transformation microstructural evolution mechanical properties
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Effects of grain size on phase transition behavior of nanocrystalline shape memory alloys 被引量:11
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作者 SUN QingPing ASLAN Ahadi +1 位作者 LI MingPeng CHEN MingXiang 《Science China(Technological Sciences)》 SCIE EI CAS 2014年第4期671-679,共9页
We report recent advances in the experimental and theoretical study of grain size(GS)effects on the thermal and mechanical properties of nanostructured NiTi polycrystalline shape memory alloy(SMA).It is shown that whe... We report recent advances in the experimental and theoretical study of grain size(GS)effects on the thermal and mechanical properties of nanostructured NiTi polycrystalline shape memory alloy(SMA).It is shown that when GS<60 nm,the superelastic stress-strain hysteresis loop area(H)of the polycrystal decreases rapidly with GS and tends to vanish as GS approaches 10 nanometers.At the same time,the temperature dependence of the transition stress also decreases with GS and eventually approaches zero,leading to a wide superelastic temperature window and breakdown of the Clausius-Claperyon relationship.Rate dependence of the stress-strain responses is significantly reduced and the cyclic stability of the material is improved by the nanocrystallization.It is proposed that the emergence of such significant changes in the behavior of the material with GS reduction originate from the large increase in the area-to-volume ratios of the nanometer-thick interfaces(grain boundary and Austenite-Martensite(A-M)interface)in the polycrystal.In particular,with GS reduction,interfacial energy terms will gradually become dominant over the bulk energy of the crystallite,eventually bring fundamental changes in the phase transition responses of the material.Modelling strategy leading to the establishment of quantitative relationships among GS,grain boundary,A-M interfaces and the macroscopic responses of the material are outlined. 展开更多
关键词 grain size effects phase transition behavior grain boundary and austenite-martensite (A-M) interface nanocrystalline NiTi shape memory alloys
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Softening micromechanical constitutive model of stress induced martensite transformation for NiTi single crystal shape memory alloy 被引量:1
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作者 ZHU YiGuo ZHANG Yang ZHAO Dan 《Science China(Physics,Mechanics & Astronomy)》 SCIE EI CAS 2014年第10期1946-1958,共13页
Based on the assumption of laminated microstructure, a micromechanical model of stress induced martensite transformation for NiTi shape memory alloys single crystal is proposed. Elasticity anisotropy and different pro... Based on the assumption of laminated microstructure, a micromechanical model of stress induced martensite transformation for NiTi shape memory alloys single crystal is proposed. Elasticity anisotropy and different proper-ties for two phases are considered. Martensite volume fraction is chosen as the internal variable that controls the phase transformation quantitatively. An effective macroscopic elasticity matrix based on the different elasticity characteristics of each phase and the martensite volume fraction are obtained with the help of the perfect interfa-cial relationships. A phase transformation driving force is derived to construct the transformation criterion. The model corresponds to a non-convexity free energy function during phase transformation, so softening behavior can be well simulated by the model. A numerical simulation is implemented for the uniaxial loading of NiTi single crystal alloy according to the model, and simulation results are proved by experimental results of polycrystal with strong {111} texture. Superelasticity, Anisotropy, the evolution of microstructure and softening behavior can be well simulated. 展开更多
关键词 shape memory alloys softening model laminated microstructures phase transformation
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